Publications

@article{warreneffects,

title = {Effects of soil amendments on hairy vetch no-till interseeded into a hayfield},

author = {Nicholas D Warren and Dorn A Cox and Richard G Smith},

year  = {2023},

date = {2023-01-01},

journal = {Agronomy Journal},

volume = {115},

pages = {887-895},

publisher = {Wiley Online Library},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{mackay2023tillage,

title = {Tillage and pesticide seed treatments have distinct effects on soil microbial diversity and function},

author = {Jessica E Mackay and Lukas T Bernhardt and Richard G Smith and Jessica Gilman Ernakovich},

year  = {2023},

date = {2023-01-01},

journal = {Soil Biology and Biochemistry},

volume = {176},

pages = {108860},

publisher = {Elsevier},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{bernhardt2022soil,

title = {Soil microbial communities vary in composition and functional strategy across soil aggregate size class regardless of tillage},

author = {Lukas T Bernhardt and Richard G Smith and A Stuart Grandy and Jessica E Mackay and Nicholas D Warren and Kevin M Geyer and Jessica G Ernakovich},

year  = {2022},

date = {2022-01-01},

journal = {Elem Sci Anth},

volume = {10},

number = {1},

pages = {00023},

publisher = {University of California Press},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{whalen2022clarifying,

title = {Clarifying the evidence for microbial-and plant-derived soil organic matter, and the path toward a more quantitative understanding},

author = {Emily D Whalen and A Stuart Grandy and Noah W Sokol and Marco Keiluweit and Jessica Ernakovich and Richard G Smith and Serita D Frey},

year  = {2022},

date = {2022-01-01},

journal = {Global Change Biology},

volume = {28},

number = {24},

pages = {7167–7185},

publisher = {Wiley Online Library},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{https://doi.org/10.1002/ecs2.4147,

title = {Cereal rye mulch biomass and crop density affect weed suppression and community assembly in no-till planted soybean},

author = {Uriel D. Menalled and Guillaume Adeux and Stéphane Cordeau and Richard G. Smith and Steven B. Mirsky and Matthew R. Ryan},

url = {https://esajournals.onlinelibrary.wiley.com/doi/abs/10.1002/ecs2.4147},

doi = {https://doi.org/10.1002/ecs2.4147},

year  = {2022},

date = {2022-01-01},

journal = {Ecosphere},

volume = {13},

number = {6},

pages = {e4147},

abstract = {Abstract The use of multiple ecological weed management tactics may be an effective solution to weed management challenges associated with reducing tillage. An experiment was conducted to assess how soybean Glycine max (L.) Merr. density and cereal rye Secale cereale L. mulch biomass affected weed suppression and community assembly in no-till production. Soybean was planted at five rates from 0 to 74 seeds m-2, and five cereal rye mulch levels were established from 0 to 2 times the ambient cereal rye biomass within each site–year. We assessed the effects of soybean density and cereal rye mulch biomass on weed suppression, weed community composition, and the functional structure of weed life cycle, emergence timing, seed weight, height, and specific leaf area traits. Weed suppression was influenced by a synergistic interaction between soybean density and cereal rye biomass. The functional dispersion (FDis) of all weed traits, when combined, was reduced by increased soybean density and mulch biomass, suggesting that high treatment intensities induced trait convergence. However, soybean density and cereal rye biomass had differing effects on the FDis and composition of individual traits, suggesting that these management practices represent unique filters during weed community assembly. Mulch biomass had a larger effect on annual weed suppression and weed community composition than soybean density. Farmers who utilize high biomass cover crop mulch for weed management may experience shifts in weed community composition toward an increased proportion of perennials and weeds with later emergence, heavier seeds, and shorter stature. Increasing soybean density may reduce perennial weed biomass, making it a valuable complement to high cereal rye mulch biomass. As such, weed management in no-till soybean is enhanced by combining multiple practices, which can enable synergistic weed suppression and the management of diverse weed functional groups.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{https://doi.org/10.1002/ael2.20080,

title = {Seed size variability has implications for achieving cover cropping goals},

author = {Natalie P. Lounsbury and Nicholas D. Warren and Julia Hobbie and Heather Darby and Matthew R. Ryan and David A. Mortensen and Richard G. Smith},

url = {https://acsess.onlinelibrary.wiley.com/doi/abs/10.1002/ael2.20080},

doi = {https://doi.org/10.1002/ael2.20080},

year  = {2022},

date = {2022-01-01},

journal = {Agricultural & Environmental Letters},

volume = {7},

number = {1},

pages = {e20080},

abstract = {Abstract It is common to use mass-based units (e.g., kg ha–1) to describe cover crop seeding rates. However, this convention obscures important information about seed size and resulting plant density in the field, which may be linked to cover crop performance and ecosystem services. Seed counts of 27 lots of commercially available winter rye (Secale cereale L.) spanned a wide range from 28,000 to 50,000 seeds kg–1. If the lots with the lowest and highest seed counts were seeded at a common mass-based seeding rate of 125~kg ha–1, it would result in a nearly twofold difference in density-based seeding rate, or 3.0 and 5.6 million live seeds ha–1. Including density-based metrics such as live seeds per area and resulting in-field plant density in research will help advance our understanding of cover crop management, and these efforts will make it easier for farmers and policymakers to tailor cover cropping practices for specific goals.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{TarpingCoverCropsFacilitatesOrganicNotillCabbageProductionandSuppressesWeeds,

title = {Tarping Cover Crops Facilitates Organic No-till Cabbage Production and Suppresses Weeds},

author = {Natalie P. Lounsbury and Bonnie B. Lounsbury and Nicholas D. Warren and Richard G. Smith},

url = {https://journals.ashs.org/hortsci/view/journals/hortsci/57/4/article-p508.xml},

doi = {10.21273/HORTSCI16389-21},

year  = {2022},

date = {2022-01-01},

journal = {HortScience},

volume = {57},

number = {4},

pages = {508 - 515},

publisher = {American Society for Horticultural Science},

address = {Washington, DC},

abstract = {Small-scale vegetable farmers are interested in cover crops and reduced tillage, but scale-appropriate technology and equipment are necessary to expand these practices to the growing segment of small farms. We sought to determine the efficacy of tarps, an increasingly popular tool on small farms, to end overwintering cover crops and provide weed suppression for subsequent no-till cabbage production. In three fields over two seasons in Maine, we grew a winter rye (Secale cereale L.) and hairy vetch (Vicia villosa L.) cover crop, which we managed by a factorial combination of tillage (no-till, till) and tarping (tarp, no-tarp) in June, followed by a transplanted cabbage crop (Brassica oleracea L. var. Capitata) in July. Within each treatment, subplots were either weeded by hand or left unweeded. Cover crop biomass ranged from 2.8 to 4.5 Mg.ha-1. Mean cabbage weights in the novel no-till system (no-till/tarp) were greater than (year 1) or equal to (year 2) those in tillage-based systems (till/no-tarp and till/tarp). In year 1, the mean cabbage weight in weeded subplots was 48% greater in no-till/tarp than in till/no-tarp systems. In unweeded subplots, this difference was 270%, highlighting the efficacy of the no-till/tarp system to reduce the impact of weeds. In year 2, weed biomass was higher with all treatments than it was in year 1, and unweeded subplots failed to produce marketable heads (i.e., >300 g). The mean cabbage weight in weeded subplots was equal among no-till/tarp, till/tarp, and till/no-tarp systems. Tarping had a strong effect on weed biomass and weed community composition measured at the time of cabbage harvest in unweeded subplots. In year 1, weed biomass at the time of cabbage harvest with tarp treatments was less than half that with no-tarp treatments. Tarps effectively facilitated the cover crop mulch-based no-till system. We propose that this system is an adaptive strategy for farmers affected by climate change. However, both cover crop production and tarping shorten the growing season. We discuss tradeoffs and opportunity costs using the metric of growing degree days.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{https://doi.org/10.1002/eap.2598,

title = {Early-season plant cover supports more effective pest control than insecticide applications},

author = {Elizabeth K. Rowen and Kirsten A. Pearsons and Richard G. Smith and Kyle Wickings and John F. Tooker},

url = {https://esajournals.onlinelibrary.wiley.com/doi/abs/10.1002/eap.2598},

doi = {https://doi.org/10.1002/eap.2598},

year  = {2022},

date = {2022-01-01},

journal = {Ecological Applications},

pages = {e2598},

abstract = {Abstract Growing evidence suggests that conservation agricultural practices, like no-till and cover crops, help protect annual crops from insect pests by supporting populations of resident arthropod predators. While adoption of conservation practices is growing, most field crop producers are also using more insecticides, including neonicotinoid seed coatings, as insurance against early-season insect pests. This tactic may disrupt benefits associated with conservation practices by reducing arthropods that contribute to biological control. We investigated the interaction between preventive pest management (PPM) and the conservation practice of cover cropping. We also investigated an alternative pest management approach, integrated pest management (IPM), which responds to insect pest risk, rather than using insecticides prophylactically. In a 3-year corn (Zea mays mays L.)–soy (Glycine max L.) rotation, we measured the response of invertebrate pests and predators to PPM and IPM with and without a cover crop. Using any insecticide provided some small reduction to plant damage in soy, but no yield benefit. In corn, vegetative cover early in the season was key to reducing pest density and damage, likely by increasing the abundance of arthropod predators. Further, PPM in year 1 decreased predation compared to a no-pest-management control. Contrary to our expectation, the IPM strategy, which required just one insecticide application, was more disruptive to the predator community than PPM, likely because the applied pyrethroid was more acutely toxic to a wider range of arthropods than neonicotinoids. Promoting early-season cover was more effective at reducing pest density and damage than either intervention-based strategy. Our results suggest that the best pest management outcomes may occur when biological control is encouraged by planting cover crops and avoiding broad-spectrum insecticides as much as possible. As part of a conservation-based approach to farming, cover crops can promote natural-enemy populations that can help provide biological effective control of insect pest populations.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{https://doi.org/10.1002/cft2.20152,

title = {Evaluating warm-season annual forages to fill summer forage gaps in short-season climates},

author = {Eric D. Billman and Igor A. Souza and Richard G. Smith and Kathy J. Soder and Nicholas Warren and André F. Brito},

url = {https://acsess.onlinelibrary.wiley.com/doi/abs/10.1002/cft2.20152},

doi = {https://doi.org/10.1002/cft2.20152},

year  = {2022},

date = {2022-01-01},

journal = {Crop, Forage & Turfgrass Management},

volume = {8},

number = {1},

pages = {e20152},

abstract = {Abstract Annual warm-season forages have been used to fill productivity and nutritional gaps during summer months throughout the southeastern United States. However, their performance and nutritive value in cooler, short-season temperate climates above 40~textdegreeN has been less well studied. This study evaluated the forage mass and nutritive value of four warm-season annual forages brown midrib [BMR] sudangrass [Sorghum bicolor ssp. Drummondii (L.) Moench], buckwheat (Fagopyrum esculentum Moench), Japanese millet [Echniochloa esculenta (A. Braun) H. Scholz], and teff [Eragrostis tef (Zuccagni) Trotter] compared with a cool-season small grain forage, oat (Avena sativa L.), and a cool-season annual forage legume, chickling vetch (Lathyrus sativus L.). Monocultures of the six annual forage species, along with a mixture of all six species, were evaluated over 2~years in southeastern New Hampshire. Forage mass and nutritive value were assessed at weekly intervals over 3~weeks in July–August, approximately 4-to-5 weeks post-germination. Across all three harvests, buckwheat, Japanese millet, and the summer mix produced greater forage mass than oat, while chickling vetch and teff produced the least. Conversely, chickling vetch had greater crude protein (CP), acid detergent fiber, and neutral detergent fiber compared with oat, while buckwheat had the lowest CP, in vitro true dry matter digestibility, and in vitro neutral detergent fiber digestibility of all the species assessed. Japanese millet produced greater forage mass while providing similar nutritive value as oat, making it a good alternative warm-season annual forage for use under cool, short growing~seasons.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{26203,

title = {Legacy Effects of ContrastingLong-Term Integrated WeedManagement Systems},

author = {Stéphane Cordeau and Auxence Baudron and Hugues Busset and Eric Vieren and Richard G. Smith and Nicolas Munier-Jolain and Guillaume Adeux},

url = {https://www.frontiersin.org/articles/10.3389/fagro.2021.769992/full},

year  = {2022},

date = {2022-01-01},

journal = {Frontiers in Agronomy},

volume = {3:769992},

abstract = {To reduce reliance on herbicides and maintain crop productivity, integrated weed management (IWM) seeks to optimize synergies between diverse sets of weed management practices combined at the cropping system scale. Nevertheless, data on weed community response to the long-term implementation of IWM practices remain scare. Here, we assessed the effects of four IWM systems with contrasting objectives and practices (S2: transition from superficial tillage to conservation agriculture; S3: no-mechanical weeding; S4: mixed mechanical and chemical weeding; S5: herbicide-free; all with 6 year rotations) compared to a conventional reference (S1: herbicide-based with systematic plowing and a 3 year rotation) on taxonomic and functional weed community composition and structure after 17 years of continuous implementation. We examined the legacy effects of these systems with a uniformity trial consisting of winter wheat managed uniformly across the systems as well as with a novel in situ weed seedbank approach involving tilled strips. We found that resulting weed communities in IWM systems were more species rich (species richness from 1.1 to 2.6 times greater) and more abundant (total density from 3.3 to 25 times greater) than those observed in the reference system, and differed in term of taxonomic and functional composition. In addition, we found that, when systems shared the same weed species, germination patterns of two thirds of the species differed between systems, highlighting the selection pressures some IWM practices exert on weeds. We showed that analyzing the superficial germinable seedbank in situ with tilled strips could provide a comprehensive view of resulting weed communities and be helpful in developing cropping systems that foster agroecological weed management.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{CONTOSTA2022107972,

title = {Climate consequences of temperate forest conversion to open pasture or silvopasture},

author = {Alexandra R. Contosta and Heidi Asbjornsen and Joseph Orefice and Apryl Perry and Richard G. Smith},

url = {https://www.sciencedirect.com/science/article/pii/S0167880922001219},

doi = {https://doi.org/10.1016/j.agee.2022.107972},

issn = {0167-8809},

year  = {2022},

date = {2022-01-01},

journal = {Agriculture, Ecosystems & Environment},

volume = {333},

pages = {107972},

abstract = {Land use change, particularly the conversion of forest to agriculture, is an important driver of climate change but is rarely considered a major factor in northern temperate regions. This study explored the climate impacts of temperate forest clearing for agriculture in the northeastern United States, hypothesizing that compared to managed cool-season pasture, forest conversion to silvopasture would moderate changes in surface temperature, soil greenhouse fluxes, and soil carbon and nutrient losses. To test this hypothesis, we conducted two land use change experiments, one in New York and the other in New Hampshire, USA. In both locations, forests have regenerated following a period of forest clearing, intensive agricultural management, and farm abandonment, such that secondary forests currently comprise ~60–80% of the land base. In both experiments, we measured microclimatic variables of air and soil temperature and soil moisture, soil greenhouse gas emissions of CO2 and N2O, and soil carbon and nitrogen content. Using a mixed-effects modeling framework, we found that near-surface air and soil temperatures were highest in converted pasture plots, lowest in reference secondary forest areas, and intermediate in the converted silvopasture treatment. Soil respiration followed a similar pattern, with elevated soil CO2 fluxes in open pastures as compared to converted silvopasture and reference secondary forest sites. Although we detected few changes in soil C among treatments, we observed higher soil N stocks and soil N2O fluxes in converted pastures but not in the converted silvopasture treatment. Our results suggest that silvopasture may offer a biogeochemical textquotedblleftmiddle groundtextquotedblright between intact secondary forests and managed open fields, retaining the climate benefits of forests while enabling expansion of the agricultural land base. Understanding the climate impacts of forest conversion to open pasture or silvopasture is critical to better anticipate the climate consequences of potentially re-emerging agricultural land uses, both across the northeastern US and other temperate forest regions globally.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Pearsons2021,

title = {Small-Grain Cover Crops Have Limited Effect on Neonicotinoid Contamination from Seed Coatings},

author = {Kirsten A. Pearsons and Elizabeth K. Rowen and Kyle R. Elkin and Kyle Wickings and Richard G. Smith and John F. Tooker},

url = {https://doi.org/10.1021/acs.est.0c05547},

doi = {10.1021/ACS.EST.0C05547},

year  = {2021},

date = {2021-04-01},

journal = {Environmental Science and Technology},

volume = {55},

number = {8},

pages = {4679–4687},

publisher = {American Chemical Society},

abstract = {Neonicotinoids from insecticidal seed coatings can contaminate soil in treated fields and adjacent areas, posing a potential risk to nontarget organisms and ecological function. To determine if cover crops can mitigate neonicotinoid contamination in treated and adjacent areas, we measured neonicotinoid concentrations for three years in no-till corn-soybean rotations, planted with or without neonicotinoid seed coatings, and with or without small grain cover crops. Although neonicotinoids were detected in cover crops, high early season dissipation provided little opportunity for winter-planted cover crops to absorb significant neonicotinoid residues; small grain cover crops failed to mitigated neonicotinoid contamination in either treated or untreated plots. As the majority of neonicotinoids from seed coatings dissipated shortly after planting, residues did not accumulate in soil, but persisted at concentrations below 5 ppb. Persistent residues could be attributed to historic neonicotinoid use and recent, nearby neonicotinoid use. Tracking neonicotinoid concentrations over time revealed a large amount of local interplot movement of neonicotinoids; in untreated plots, contamination was higher when plots were less isolated from treated plots.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{https://doi.org/10.1111/wre.12505,

title = {Weed germinable seedbanks of rice–wheat systems in the Eastern Indo-Gangetic Plains: Do tillage and edaphic factors explain community variation?},

author = {Carolyn J. Lowry and Daniel C. Brainard and Virender Kumar and Richard G. Smith and Madhulika Singh and Pankaj Kumar and Ajay Kumar and Vipin Kumar and Rajiv K. Joon and Raj K. Jat and Shishpal Poonia and Ram K. Malik and Andrew McDonald},

url = {https://onlinelibrary.wiley.com/doi/abs/10.1111/wre.12505},

doi = {https://doi.org/10.1111/wre.12505},

year  = {2021},

date = {2021-01-01},

journal = {Weed Research},

volume = {61},

number = {6},

pages = {475-485},

abstract = {Abstract Zero tillage (ZT) is widely promoted throughout India’s Eastern Indo-Gangetic Plains (IGP) because of its potential to increase wheat productivity and resilience to abiotic stresses. Weeds remain a major barrier to ZT adoption, yet it remains unclear how ZT will influence weed communities in the Eastern-IGP. The primary objective of this study was to characterise the composition of the germinable weed seedbank sampled just prior to the wheat phase of rice–wheat farms in Bihar and Eastern Uttar Pradesh, and examine whether adoption of ZT wheat has shifted weed community composition compared to conventional tillage (CT). Additionally, we examined whether edaphic properties and topography (upland vs. lowland) explain variation in germinable weed seedbank communities. In December 2014, we evaluated the germinable seedbank from 72 fields differing in their historic (>=3~year) tillage practices (ZT vs. CT) in three regions: Samastipur–Vaishali–Muzaffarpur (SVM), Ara–Buxar and Maharajgunj–Kushinagar. Weed community composition and species richness varied by region and topography. ZT adoption was associated with lower relative density of Chenopodium album in the germinable seedbank and lower emergence of Phalaris minor seedlings within farmers’ fields. In upland topographies of the SVM region, ZT adoption was also associated with greater relative abundance of Solanum nigrum in the weed seedbank. However, differences between tillage systems in individual species were not large enough to result in detection of differences at the whole-community level. Variation in edaphic properties, most notably soil texture and pH, explained 51% of the variation in the weed seedbank community. Our work suggests several frequent but poorly understood species (e.g. Mazus pumilus and Grangea maderaspatana) in Eastern IGP for which future research should quantify their effects on crop yields. Finally, future work surveying weed species abundance at harvest could further determine the dominant problematic species in these regions.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{https://doi.org/10.1002/cft2.20113,

title = {Winter annual forage mass–nutritive value trade-offs are affected by harvest timing},

author = {Eric D. Billman and Igor A. Souza and Richard G. Smith and Kathy J. Soder and Nicholas Warren and Fabio A. Teixeira and Andre F. Brito},

url = {https://acsess.onlinelibrary.wiley.com/doi/abs/10.1002/cft2.20113},

doi = {https://doi.org/10.1002/cft2.20113},

year  = {2021},

date = {2021-01-01},

journal = {Crop, Forage & Turfgrass Management},

volume = {7},

number = {2},

pages = {e20113},

abstract = {Abstract Annual cool-season forage crops could fill the gaps in spring forage availability that are typical in perennial pastures in the northeastern United States. Despite their potential as supplemental forages, few studies have examined the productivity–quality tradeoffs of annual forages grown as monocultures or mixtures. This study compared five species of winter annual forages grown as monocultures and mixtures for forage mass production and nutritive value across three harvest timepoints. Beginning in fall 2015, plots were planted in monocultures of cereal rye (Secale cereale L.), barley (Hordeum vulgare L.), triticale [texttimesTriticosecale Wittm. ex A. Camus (Secale texttimes Triticum)], wheat (Triticum aestivum L.), and hairy vetch (Vicia villosa Roth), as well as a mix of all five species. Samples were taken on 1, 7, and 14 June 2016, and on 3, 10, and 17 May 2017 to determine forage mass, nutritive value in the second year, and tradeoffs between biomass and nutritive value. The mixture’s forage mass always ranked similarly to the best performing monoculture treatments. All monocultures except hairy vetch had increased forage mass at later harvests. In vitro digestibility of neutral detergent fiber was lower in later harvests. Triticale consistently had the greatest forage mass. Barley had greater energy and lower fiber concentrations than the other species. The results of this study suggest that triticale and barley have the most potential for supplementing spring perennial forage production.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Menalled2021,

title = {High Seeding Rates and Low Soil Nitrogen Environments Optimize Weed Suppression and Profitability in Organic No-Till Planted Soybean},

author = {Uriel Danilo Menalled and Sarah J Pethybridge and Chris J Pelzer and Richard G Smith and Antonio DiTommaso and Matthew R Ryan},

url = {https://www.researchgate.net/publication/351387794},

doi = {10.3389/fagro.2021.678567},

year  = {2021},

date = {2021-01-01},

journal = {Frontiers in Agronomy},

volume = {3},

abstract = {No-till planting crops into rolled-crimped cover crops can improve soil health while reducing labor and fuel requirements compared with traditional tillage-based production. However, little information is available to help farmers optimize the management of organic no-till planted crops. Weed suppression, crop yield, and profitability were assessed across soybean [Glycine max (L.) Merr.] seeding rates and soil nitrogen environments in an experiment conducted at two sites in central New York. Soybeans were no-till planted into rolled-crimped cereal rye (Secale cereale L.) at 0, 185,000, 371,000, 556,000, and 741,000 seeds ha-1. Three rates (0, 63, or 125 kg ha-1) of sodium nitrate (15-0-2) were applied across seeding rates to create different soil nitrogen environments. When pooled over sites, the lowest weed biomass occurred at the highest soybean density in the lowest soil nitrogen environment. An interaction was observed between soybean seeding rate and nitrogen treatments on weed communities. Soybean yield increased asymptotically with crop density and was not affected by nitrogen or site treatments. When pooled over nitrogen treatments and sites, partial returns to the soybean seeding rates were maximized at $2,238 ha-1 with 527,800 seeds ha-1. Results suggest that crop density is an important lever for optimizing weed suppression and crop yield in organic no-till soybean, and that managing for low soil nitrogen conditions may further enhance weed suppression while maintaining high yields.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Mortensen2020,

title = {Confronting Barriers to Cropping System Diversification},

author = {David A. Mortensen and Richard G. Smith},

doi = {10.3389/FSUFS.2020.564197/PDF},

year  = {2020},

date = {2020-11-01},

journal = {Frontiers in Sustainable Food Systems},

volume = {4},

publisher = {Frontiers Media S.A.},

abstract = {There is no shortage of data demonstrating that diversified cropping systems can sustain high levels of productivity with fewer external inputs and lower externalities compared to more simplified systems. Similarly, data exist indicating diverse cropping systems have greater capacity to buffer against and adapt to weather extremes associated with climate change. Yet, agriculture in the US Corn Belt and other major crop production regions around the world continues to move toward simplified rotations grown over increasingly large acreages. If our goal is to see more of the agricultural landscape made up of diverse agricultural systems and the ecosystem services they provide, it is critical we understand and creatively address the factors that both give rise to monocultures and reinforce their entrenchment at the exclusion of more diversified alternatives. Using the current state of farming and agriculture policy in the US as a case study, we argue that a pernicious feedback exists in which economic and policy forces incentivize low diversity cropping systems which then become entrenched due, in part, to a lack of research and policy aimed at enabling farming practices that support the diversification of cropping systems at larger spatial scales. We use the recent example of dicamba-resistant crops to illustrate the nature of this pernicious feedback and offer suggestions for creating textquotedblleftvirtuous feedbackstextquotedblright aimed at achieving a more diversified agriculture.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Wilhelm2020,

title = {Resident and stakeholder perceptions of ecosystem services associated with agricultural landscapes in New Hampshire},

author = {Jennifer A. Wilhelm and Richard G. Smith and Maria Christina Jolejole-Foreman and Stephanie Hurley},

doi = {10.1016/J.ECOSER.2020.101153},

year  = {2020},

date = {2020-10-01},

journal = {Ecosystem Services},

volume = {45},

publisher = {Elsevier B.V.},

abstract = {Converting non-agricultural land to agricultural uses can result in trade-offs in ecosystem services. As provisioning services increase on new agricultural land, supporting, regulating, and cultural services may decrease. An improved understanding of how stakeholders value different land use types in terms of their perceived ecosystem services, as well as the relative visual appeal of different agricultural landscape features, could assist policymakers and land use planners in decision-making related to agricultural land use in New England, USA. We surveyed two survey samples in New Hampshire, food system stakeholders (e.g., farmers, public health professionals, and technical assistance providers) and the general population, to explore how perception of the visual appeal of specific farmland use types and importance of ecosystem services specifically related to agricultural land might differ between survey samples. Our objectives were to (1) explore how New Hampshire residents perceive the importance of seven ecosystem services, (2) evaluate how two groups of New Hampshire residents—the general public and those who indicated working with or in a food systems sector (food system stakeholders)—perceive these ecosystem services provided by specific agricultural landscapes and determine how those perceptions relate to the visual appeal of each landscape, and (3) assess how eight socio-economic factors may account for the differences between each survey sample in terms of their landscape perception and preference. Roughly 600 New Hampshire residents completed the survey, including 494 individuals from the public and 103 food system stakeholders. From a list of seven ecosystem services, clean water was ranked as the most important across both survey samples, with no significant difference between samples, while food production was ranked significantly higher by the food system stakeholders (p <= 0.001). Likewise, on a scale of most (4) to least (1) appealing, food system stakeholders ranked photorealistic visualizations of cropland higher than the public (p <= 0.001). Additionally, food system stakeholders ranked the appeal of forestland lower than the public (p = 0.007). Our findings suggest that there are differences in landscape preferences and perception of ecosystem service benefits between the general public and those who work with or in the food system. Future research is needed to determine how these differences in perception might affect land use planning and policymaking related to agricultural expansion and forestland preservation.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Menalled2020,

title = {Soil-Mediated Effects on Weed-Crop Competition: Elucidating the Role of Annual and Perennial Intercrop Diversity Legacies},

author = {Uriel D. Menalled and K. Ann Bybee-Finley and Richard G. Smith and Antonio DiTommaso and Sarah J. Pethybridge and Matthew R. Ryan},

url = {https://www.mdpi.com/2073-4395/10/9/1373/htm https://www.mdpi.com/2073-4395/10/9/1373},

doi = {10.3390/AGRONOMY10091373},

year  = {2020},

date = {2020-09-01},

journal = {Agronomy 2020, Vol. 10, Page 1373},

volume = {10},

number = {9},

pages = {1373},

publisher = {Multidisciplinary Digital Publishing Institute},

abstract = {Crop diversity may mediate the intensity of weed-crop competition by altering soil nutrient availability and plant-soil microbe interactions. A greenhouse experiment was conducted to analyze weed-crop competition in soils with varying crop diversity legacies. Soil greenhouse treatments included field soils (i.e., soil nutrient and microbial legacies), a sterile greenhouse potting mix inoculated with microorganisms of the field soils (i.e., microbial legacies), and a sterile greenhouse potting mix. Soils for the greenhouse experiment were sampled and assessed after two-years of conditioning with annual and perennial cropping systems under four levels of intercrop diversity. The greenhouse experiment involved growing one sorghum sudangrass (Sorghum bicolor (L.) Moench × S. sudanese Piper) crop plant and zero to six common lambsquarters (Chenopodium album L.) weed plants in soil from each diversity and cropping system treatment. The weed density treatments created a weed-crop competition gradient, which was used to quantify legacy effects of crop diversity. Weed-crop competition increased with crop diversity in both the field soil and inoculated soil treatments in the annual system. In the perennial system, differences in weed-crop competition intensity were driven by crop yield potential. In the perennial field soil treatment, crop yield potential was greatest in the highest diversity treatment, whereas in the perennial inoculated soil treatment, crop yield potential was greatest in the lowest diversity treatment. Results show potential for negative effects from previous crop diversity on weed-crop competition, and the divergent impact of microbial and nutrient legacies on crop yield potential. Future research should aim to evaluate the consistency of legacy effects and identify principles that can guide soil and crop management, especially in conservation agriculture where soil tillage and its microbial legacy reducing effects are minimized.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Coble2020,

title = {Influence of forest-to-silvopasture conversion and drought on components of evapotranspiration},

author = {Adam P. Coble and Alexandra R. Contosta and Richard G. Smith and Nathan W. Siegert and Matthew Vadeboncoeur and Katie A. Jennings and Anthony J. Stewart and Heidi Asbjornsen},

doi = {10.1016/j.agee.2020.106916},

issn = {01678809},

year  = {2020},

date = {2020-06-01},

journal = {Agriculture, Ecosystems and Environment},

volume = {295},

pages = {106916},

publisher = {Elsevier B.V.},

abstract = {The northeastern U.S. is projected to experience more frequent short-term (1-2 month) droughts interspersed among larger precipitation events. Agroforestry practices such as silvopasture may mitigate these impacts of climate change while maintaining economic benefits of both agricultural and forestry practices. This study evaluated the effects of forest-to-silvopasture (i.e., 50 % thinning) conversion on the components of evapotranspiration (transpiration, rainfall interception, and soil evaporation) during the growing season of 2016. The study coincided with a late-summer drought throughout the northeastern U.S., which allowed us to also evaluate the effects of forest-to-silvopasture conversion on drought responses of multiple tree species, including Pinus strobus, Tsuga canadensis, and Quercus rubra. In the reference forest and silvopasture, we observed declining soil moisture and tree water use during the drought for all three tree species. However, the decline in P. strobus water use in response to declining soil moisture in the silvopasture was not as steep as compared with the reference forest, resulting in greater water use in the silvopasture for this species. In contrast, we did not detect different water-use responses between forest and silvopasture in T. canadensis or Q. rubra. This suggests that forest-to-silvopasture conversion via thinning can alleviate drought stress for P. strobus and that this species may be more sensitive to moisture stress when competition for water is high in denser stands. Evapotranspiration was 35 % lower in the silvopasture compared with the reference forest, primarily a result of lower transpiration and rainfall interception. While soil evaporation was greater in the silvopasture, this was not enough to offset the considerably lower transpiration and interception. We observed greater radial tree growth 1–3 years following conversion in the silvopasture as compared with the reference forest for T. canadensis and Q. rubra, but not for P. strobus. Overall, our results suggest that forest conversion to silvopasture (in lieu of clearcutting for new pasture) may mitigate the impacts of agricultural land use intensification and climate change on ecosystem services, especially in terms of sustaining hydrologic regulation functions. Further study is required to determine the generality of these results and whether these benefits extend beyond the first few years post-conversion.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Jilling2020,

title = {Rapid and distinct responses of particulate and mineral-associated organic nitrogen to conservation tillage and cover crops},

author = {Andrea Jilling and Daniel Kane and Alwyn Williams and Anthony C. Yannarell and Adam Davis and Nicholas R. Jordan and Roger T. Koide and David A. Mortensen and Richard G. Smith and Sieglinde S. Snapp and Kurt A. Spokas and A. Stuart Grandy},

doi = {10.1016/j.geoderma.2019.114001},

issn = {00167061},

year  = {2020},

date = {2020-02-01},

journal = {Geoderma},

volume = {359},

pages = {114001},

publisher = {Elsevier B.V.},

abstract = {Particulate organic matter (POM) is considered an textquotedblleftactivetextquotedblright source of nitrogen (N) in cultivated soils, responding readily to management and being more physically accessible to decomposers than mineral-associated forms of organic matter. However, there is increasing evidence that mineral-associated organic matter (MAOM) can also exhibit short-term changes to management that may impact plant and microbial N dynamics. In this study, we investigated how N within soil organic matter fractions responded to three years of tillage and cover crop treatments. We collected soils from a row-crop (maize-soybean rotation) field experiment replicated across three sites in the north central and mid-Atlantic United States: a high-soil organic matter site (3.1% soil organic carbon) in Illinois (IL) and two sites in Michigan (MI) and Pennsylvania (PA) with lower soil organic matter content (1.0% and 1.4% soil organic carbon, respectively). Management treatments included two levels of tillage (chisel plow and ridge tillage) and two levels of cover crop (with and without rye cover crop). Using an optimized sonication method coupled with particle size separation, we isolated and analyzed for N content free POM, occluded POM, a coarse silt fraction, and MAOM. Using partial least squares regression, we also explored broad cross-site relationships between soil organic matter (SOM) fractions, soil N availability, and crop performance. Both particulate and fine fractions responded to tillage and cover crop treatments, but patterns varied by site and fraction. In the low-SOM MI and PA soils, ridge tillage and cover cropping both increased N within POM fractions. The response to ridge tillage was most pronounced, with a 76% and 24% increase in occluded POM N content in MI and PA, respectively. In contrast, at the IL site (high-SOM), the inclusion of cover crops led to higher N, specifically within the fine fractions (coarse silt and MAOM). Cover cropping increased MAOM N content in IL by 24%. When analyzing all sites together, variables associated with fine fractions were more closely associated with N mineralization and crop performance. MAOM can be responsive to short-term management practices and, along with POM, may also be potential sources of N for crops.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Jilling2020b,

title = {Rapid and distinct responses of particulate and mineral-associated organic nitrogen to conservation tillage and cover crops},

author = {Andrea Jilling and Daniel Kane and Alwyn Williams and Anthony C. Yannarell and Adam Davis and Nicholas R. Jordan and Roger T. Koide and David A. Mortensen and Richard G. Smith and Sieglinde S. Snapp and Kurt A. Spokas and A. Stuart Grandy},

doi = {10.1016/j.geoderma.2019.114001},

issn = {00167061},

year  = {2020},

date = {2020-02-01},

journal = {Geoderma},

volume = {359},

pages = {114001},

publisher = {Elsevier B.V.},

abstract = {Particulate organic matter (POM) is considered an textquotedblleftactivetextquotedblright source of nitrogen (N) in cultivated soils, responding readily to management and being more physically accessible to decomposers than mineral-associated forms of organic matter. However, there is increasing evidence that mineral-associated organic matter (MAOM) can also exhibit short-term changes to management that may impact plant and microbial N dynamics. In this study, we investigated how N within soil organic matter fractions responded to three years of tillage and cover crop treatments. We collected soils from a row-crop (maize-soybean rotation) field experiment replicated across three sites in the north central and mid-Atlantic United States: a high-soil organic matter site (3.1% soil organic carbon) in Illinois (IL) and two sites in Michigan (MI) and Pennsylvania (PA) with lower soil organic matter content (1.0% and 1.4% soil organic carbon, respectively). Management treatments included two levels of tillage (chisel plow and ridge tillage) and two levels of cover crop (with and without rye cover crop). Using an optimized sonication method coupled with particle size separation, we isolated and analyzed for N content free POM, occluded POM, a coarse silt fraction, and MAOM. Using partial least squares regression, we also explored broad cross-site relationships between soil organic matter (SOM) fractions, soil N availability, and crop performance. Both particulate and fine fractions responded to tillage and cover crop treatments, but patterns varied by site and fraction. In the low-SOM MI and PA soils, ridge tillage and cover cropping both increased N within POM fractions. The response to ridge tillage was most pronounced, with a 76% and 24% increase in occluded POM N content in MI and PA, respectively. In contrast, at the IL site (high-SOM), the inclusion of cover crops led to higher N, specifically within the fine fractions (coarse silt and MAOM). Cover cropping increased MAOM N content in IL by 24%. When analyzing all sites together, variables associated with fine fractions were more closely associated with N mineralization and crop performance. MAOM can be responsive to short-term management practices and, along with POM, may also be potential sources of N for crops.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{26202,

title = {Forest conversion to silvopasture and open pasture: effects on soil hydraulic properties},

author = {Anthony Stewart and Adam Coble and Alexandra R. Contosta and Joseph N. Orefice and Richard G. Smith and Heidi Asbjornsen},

year  = {2020},

date = {2020-01-01},

journal = {Agroforestry Systems},

volume = {94},

pages = {869-879},

abstract = {Growing demand for local products in the northeastern U.S. may incentivize forest conversion to pasture, degrading critical soil hydrologic properties such as surface infiltration (Kh) and subsurface saturated hydraulic conductivity (Ksat). Silvopasture, combining tree cover and grazing, may mitigate these impacts by maintaining the positive effects of trees on soil hydraulic properties. We tested this hypothesis using an experimental field manipulation to compare effects of forest conversion to open pasture versus silvopasture on Kh and Ksat at the Organic Dairy Research Farm (ODRF) and North Branch Farm (NBF). Measurements of surface Kh and Ksat at two soil depths (15 cm and 30 cm) were taken 1 and 4 years after treatment establishment at ODRF and NBF, respectively. Data were analyzed using a mixed effects modeling framework. Results show 15 cm Ksat was significantly lower in pasture compared to forest across both sites. However, in contrast to our hypothesis, soil hydraulic properties in silvopasture did not differ from other treatments at either site. Notwithstanding, silvopasture 15 cm Ksat at ODRF (9.4 cm h-1) was statistically similar to both the forest (22.6 cm h-1) and pasture (3.4 cm h-1) and exhibited a weak positive correlation with proximity to trees (R2 = 0.219, P = 0.042). In conclusion, our study did not find strong evidence that recently established silvopastures mitigate negative hydrologic impacts of forest conversion. Future research should focus on a broader range of northeastern sites and include greater replication over longer time scales to better elucidate opportunities for silvopasture.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{lounsbury_warren_wolfe_smith_2020,

title = {Investigating tarps to facilitate organic no-till cabbage production with high-residue cover crops},

author = {Natalie P Lounsbury and Nicholas D Warren and Seamus D Wolfe and Richard G Smith},

doi = {10.1017/S1742170518000509},

year  = {2020},

date = {2020-01-01},

journal = {Renewable Agriculture and Food Systems},

volume = {35},

number = {3},

pages = {227–233},

publisher = {Cambridge University Press},

abstract = {High-residue cover crops can facilitate organic no-till vegetable production when cover crop biomass production is sufficient to suppress weeds (>8000 kg ha-1), and cash crop growth is not limited by soil temperature, nutrient availability, or cover crop regrowth. In cool climates, however, both cover crop biomass production and soil temperature can be limiting for organic no-till. In addition, successful termination of cover crops can be a challenge, particularly when cover crops are grown as mixtures. We tested whether reusable plastic tarps, an increasingly popular tool for small-scale vegetable farmers, could be used to augment organic no-till cover crop termination and weed suppression. We no-till transplanted cabbage into a winter rye (Secale cereale L.)-hairy vetch (Vicia villosa Roth) cover crop mulch that was terminated with either a roller-crimper alone or a roller-crimper plus black or clear tarps. Tarps were applied for durations of 2, 4 and 5 weeks. Across tarp durations, black tarps increased the mean cabbage head weight by 58% compared with the no tarp treatment. This was likely due to a combination of improved weed suppression and nutrient availability. Although soil nutrients and biological activity were not directly measured, remaining cover crop mulch in the black tarp treatments was reduced by more than 1100 kg ha-1 when tarps were removed compared with clear and no tarp treatments. We interpret this as an indirect measurement of biological activity perhaps accelerated by lower daily soil temperature fluctuations and more constant volumetric water content under black tarps. The edges of both tarp types were held down, rather than buried, but moisture losses from the clear tarps were greater and this may have affected the efficacy of clear tarps. Plastic tarps effectively killed the vetch cover crop, whereas it readily regrew in the crimped but uncovered plots. However, emergence of large and smooth crabgrass (Digitaria spp.) appeared to be enhanced in the clear tarp treatment. Although this experiment was limited to a single site-year in New Hampshire, it shows that use of black tarps can overcome some of the obstacles to implementing cover crop-based no-till vegetable productions in northern climates.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Smith2020,

title = {Are cover crop mixtures better at suppressing weeds than cover crop monocultures?},

author = {Richard G. Smith and Nicholas D. Warren and Stéphane Cordeau},

doi = {10.1017/wsc.2020.12},

issn = {15502759},

year  = {2020},

date = {2020-01-01},

journal = {Weed Science},

volume = {68},

number = {2},

pages = {186–194},

abstract = {Cover crops are increasingly being used for weed management, and planting them as diverse mixtures has become an increasingly popular strategy for their implementation. While ecological theory suggests that cover crop mixtures should be more weed suppressive than cover crop monocultures, few experiments have explicitly tested this for more than a single temporal niche. We assessed the effects of cover crop mixtures (5- or 6-species and 14-species mixtures) and monocultures on weed abundance (weed biomass) and weed suppression at the time of cover crop termination. Separate experiments were conducted in Madbury, NH, from 2014 to 2017 for each of three temporal cover-cropping niches: summer (spring planting-summer termination), fall (summer planting-fall termination), and spring (fall planting-subsequent spring termination). Regardless of temporal niche, mixtures were never more weed suppressive than the most weed-suppressive cover crop grown as a monoculture, and the more diverse mixture (14 species) never outperformed the less diverse mixture. Mean weed-suppression levels of the best-performing monocultures in each temporal niche ranged from 97% to 98% for buckwheat (Fagopyrum esculentum Moench) in the summer niche and forage radish (Raphanus sativus L. var. Niger J. Kern.) in the fall niche, and 83% to 100% for triticale (texttimesTriticosecale Wittm. ex A. Camus [Secale texttimes Triticum]) in the winter-spring niche. In comparison, weed-suppression levels for the mixtures ranged from 66% to 97%, 70% to 90%, and 67% to 99% in the summer, fall, and spring niches, respectively. Stability of weed suppression, measured as the coefficient of variation, was two to six times greater in the best-performing monoculture compared with the most stable mixture, depending on the temporal niche. Results of this study suggest that when weed suppression is the sole objective, farmers are more likely to achieve better results planting the most weed-suppressive cover crop as a monoculture than a mixture.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Lowry2020,

title = {Effects of expanding functional trait diversity on productivity and stability in cultivar mixtures of perennial ryegrass},

author = {Carolyn J. Lowry and Sidney C. Bosworth and Sarah C. Goslee and Richard J. Kersbergen and Fredric W. Pollnac and R. Howard Skinner and Nicholas D. Warren and Richard G. Smith},

doi = {10.1016/j.agee.2019.106691},

issn = {01678809},

year  = {2020},

date = {2020-01-01},

journal = {Agriculture, Ecosystems and Environment},

volume = {287},

pages = {106691},

publisher = {Elsevier B.V.},

abstract = {Cultivar mixtures can provide a host of beneficial agroecosystem services in annual grain crops; however, it remains unclear whether these same benefits apply to perennial forage cropping systems, or the degree to which beneficial effects depend on the functional trait diversity of the mixtures. We conducted a field experiment across four locations in the Northeast US in which we grew perennial ryegrass cultivar mixtures varying in cultivar number and range of expression of three functional traits (winter hardiness, heading date, and extended growth) and assessed the effects on dry matter yield and inter-annual yield variability. Trait ratings supplied by the seed company were related to observed variation in perennial ryegrass productivity and/or stability at both the individual cultivar and mixture levels. Winter hardiness was associated with greater perennial ryegrass cumulative biomass, and lower interannual stability. In contrast, extended growth was associated with lower cumulative biomass, and both extended growth and later heading date were associated with greater interannual variability. Overall, cultivar richness was negatively associated with perennial ryegrass biomass and stability; however, the best performing mixtures performed as well as the recommended cultivar for the region. When comparing mixtures with equal cultivar richness, functional trait diversity measured as the additive trait range—the summed range of the three traits associated with the cultivars in that mixture—was positively associated with biomass production and over-yielding, but not interannual variability. Cultivar mixtures of perennial ryegrass can lead to improved forage production when specific functional traits are optimized within mixtures. Our results support the growing understanding that efforts to ecologically intensify agriculture through enhancement of crop diversity are more likely to succeed when they explicitly consider the functional traits of the crops involved rather than solely numbers of cultivars or species.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Forest conversion to silvopasture and open pasture: effects on soil hydraulic properties.},

author = {Stewart A, Coble A, Contosta AR, Orefice JN, Smith RG, Asbjornsen H.},

doi = {https://doi.org/10.1007/s10457-019-00454-9},

year  = {2019},

date = {2019-11-12},

journal = {Agroforestry Systems},

pages = {1-11},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Ball2019,

title = {Weed community structure and soybean yields in a long-term organic cropping systems experiment},

author = {Margaret G. Ball and Brian A. Caldwell and Antonio DiTommaso and Laurie E. Drinkwater and Charles L. Mohler and Richard G. Smith and Matthew R. Ryan},

doi = {10.1017/wsc.2019.44},

issn = {15502759},

year  = {2019},

date = {2019-11-01},

journal = {Weed Science},

volume = {67},

number = {6},

pages = {673–681},

publisher = {Cambridge University Press},

abstract = {Weed management is a major challenge in organic crop production, and organic farms generally harbor larger weed populations and more diverse communities compared with conventional farms. However, little research has been conducted on the effects of different organic management practices on weed communities and crop yields. In 2014 and 2015, we measured weed community structure and soybean [Glycine max (L.) Merr.] yield in a long-term experiment that compared four organic cropping systems that differed in nutrient inputs, tillage, and weed management intensity: (1) high fertility (HF), (2) low fertility (LF), (3) enhanced weed management (EWM), and (4) reduced tillage (RT). In addition, we created weed-free subplots within each system to assess the impact of weeds on soybean yield. Weed density was greater in the LF and RT systems compared with the EWM system, but weed biomass did not differ among systems. Weed species richness was greater in the RT system compared with the EWM system, and weed community composition differed between RT and other systems. Our results show that differences in weed community structure were primarily related to differences in tillage intensity, rather than nutrient inputs. Soybean yield was lower in the EWM system compared with the HF and RT systems. When averaged across all four cropping systems and both years, soybean yield in weed-free subplots was 10% greater than soybean yield in the ambient weed subplots that received standard management practices for the systems in which they were located. Although weed competition limited soybean yield across all systems, the EWM system, which had the lowest weed density, also had the lowest soybean yield. Future research should aim to overcome such trade-offs between weed control and yield potential, while conserving weed species richness and the ecosystem services associated with increased weed diversity.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Schnecker2019,

title = {Substrate quality and concentration control decomposition and microbial strategies in a model soil system},

author = {Jörg Schnecker and Timothy Bowles and Erik A. Hobbie and Richard G. Smith and A. Stuart Grandy},

doi = {10.1007/s10533-019-00571-8},

issn = {1573515X},

year  = {2019},

date = {2019-05-01},

journal = {Biogeochemistry},

volume = {144},

number = {1},

pages = {47–59},

publisher = {Springer International Publishing},

abstract = {Soil carbon models typically scale decomposition linearly with soil carbon (C) concentration, but this linear relationship has not been experimentally verified. Here we investigated the underlying biogeochemical mechanisms controlling the relationships between soil C concentration and decomposition rates. We incubated a soil/sand mixture with increasing amounts of finely ground plant residue in the laboratory at constant temperature and moisture for 63~days. The plant residues were rye (Secale cereale, C/N ratio of 23) and wheat straw (Triticum spp., C/N ratio of 109) at seven soil C concentrations ranging from 0.38 to 2.99%. We measured soil respiration, dissolved organic carbon (DOC) concentrations, microbial biomass, and potential enzyme activities over the course of the incubation. Rye, which had higher N and DOC contents, lost 6 to 8 times more C as CO2 compared to wheat residue. Under rye and wheat amendment, absolute C losses as CO2 (calculated per g dry soil) increased linearly with C concentration while relative C losses as CO2 (expressed as percent of initial C) increased with C concentration following a quadratic function. In low C concentration treatments (0.38–0.79% OC), DOC decreased gradually from day 3 to day 63, microbial C increased towards the end in the rye treatment or decreased only slightly with straw amendment, and microbes invested in general enzymes such as proteases and oxidative enzymes. At increasing C levels, enzyme activity shifted to degrading cellulose after 15~days and degrading microbial necromass (e.g. chitin) after 63~days. At the highest C concentrations (2.99% OC), microbial biomass peaked early in the incubation and remained high in the rye treatment and decreased only slightly in the wheat treatment. While wheat lost C as CO2 constantly at all C concentrations, respiration dynamics in the rye treatment strongly depended on C concentration. Our results indicate that litter quality and C concentration regulate enzyme activities, DOC concentrations, and microbial respiration. The potential for non-linear relationships between soil C concentration and decomposition may need to be considered in soil C models and soil C sequestration management approaches.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Orefice2019,

title = {Forage productivity and profitability in newly-established open pasture, silvopasture, and thinned forest production systems},

author = {Joseph Orefice and Richard G. Smith and John Carroll and Heidi Asbjornsen and Theodore Howard},

doi = {10.1007/s10457-016-0052-7},

issn = {15729680},

year  = {2019},

date = {2019-02-01},

journal = {Agroforestry Systems},

volume = {93},

number = {1},

pages = {51–65},

publisher = {Springer Netherlands},

abstract = {There is growing interest among farmers in the northeast US in silvopasture and other practices that would help them expand their agricultural land base in this forested region. Unfortunately, little quantitative data exist regarding forage performance and economic outcomes associated with different forest-to-agriculture conversion strategies, particularly for the northern tier of states. This research examined forage dry matter production and quality in six forage treatments (orchardgrass, bluegrass, brome, and perennial ryegrass bicultures with white clover; cut hay; and a control) in newly-established silvopastures and open pastures converted from an early successional northern hardwood forest in New York. In addition, we conducted a financial analysis of the establishment of both agricultural systems, as well as a thinned forest treatment managed solely for wood products. Total forage dry matter production (planted forages plus volunteer grasses) was greater in open pastures than silvopastures in the first year after establishment; however, no differences in total forage production were found between silvopastures and open pastures in June or August of the second year. Total forage dry matter production was greater in the orchardgrass-white clover biculture compared to the control treatment in both years. Orchardgrass percent crude protein was lower in open pastures (10.7%) compared to silvopastures (12.9%) in June of year two. The financial analysis indicated that silvopasture outperformed open pasture and thinned forest treatments in terms of both IRR and NPV. We conclude that forage production in silvopastures can be competitive with that in open pastures on sites with a similar, forested, starting condition.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Williams2018,

title = {A regionally-adapted implementation of conservation agriculture delivers rapid improvements to soil properties associated with crop yield stability},

author = {Alwyn Williams and Nicholas R. Jordan and Richard G. Smith and Mitchell C. Hunter and Melanie Kammerer and Daniel A. Kane and Roger T. Koide and Adam S. Davis},

doi = {10.1038/s41598-018-26896-2},

issn = {20452322},

year  = {2018},

date = {2018-12-01},

journal = {Scientific Reports},

volume = {8},

number = {1},

pages = {1–8},

publisher = {Nature Publishing Group},

abstract = {Climate models predict increasing weather variability, with negative consequences for crop production. Conservation agriculture (CA) may enhance climate resilience by generating certain soil improvements. However, the rate at which these improvements accrue is unclear, and some evidence suggests CA can lower yields relative to conventional systems unless all three CA elements are implemented: reduced tillage, sustained soil cover, and crop rotational diversity. These cost-benefit issues are important considerations for potential adopters of CA. Given that CA can be implemented across a wide variety of regions and cropping systems, more detailed and mechanistic understanding is required on whether and how regionally-adapted CA can improve soil properties while minimizing potential negative crop yield impacts. Across four US states, we assessed short-term impacts of regionally-adapted CA systems on soil properties and explored linkages with maize and soybean yield stability. Structural equation modeling revealed increases in soil organic matter generated by cover cropping increased soil cation exchange capacity, which improved soybean yield stability. Cover cropping also enhanced maize minimum yield potential. Our results demonstrate individual CA elements can deliver rapid improvements in soil properties associated with crop yield stability, suggesting that regionally-adapted CA may play an important role in developing high-yielding, climate-resilient agricultural systems.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Whalen2018,

title = {Manganese limitation as a mechanism for reduced decomposition in soils under atmospheric nitrogen deposition},

author = {Emily D. Whalen and Richard G. Smith and A. Stuart Grandy and Serita D. Frey},

doi = {10.1016/j.soilbio.2018.09.025},

issn = {00380717},

year  = {2018},

date = {2018-12-01},

journal = {Soil Biology and Biochemistry},

volume = {127},

pages = {252–263},

publisher = {Elsevier Ltd},

abstract = {Long-term atmospheric nitrogen (N) deposition has been shown to reduce leaf litter and lignin decomposition in temperate forest soils, leading to an accumulation of soil carbon (C). Reduced decomposition has been accompanied by altered structure and function of fungal communities, the primary decomposers in forest ecosystems; however, a mechanistic understanding of fungal responses to chronic N enrichment is lacking. A reduction in soil and litter manganese (Mn) concentrations under N enrichment (i.e., Mn limitation) may help explain these observations, because Mn is a cofactor and regulator of lignin-decay enzymes produced by fungi. We conducted a laboratory study to evaluate the effect of Mn availability on decomposition dynamics in chronically N-enriched soils. We measured litter mass loss, lignin relative abundance, and lignin-decay enzyme activities, and characterized the litter fungal community by ITS2 metabarcoding. We observed a significant positive correlation between Mn availability and lignin-decay enzyme activities. In addition, long-term (28 years) N enrichment increased the relative abundance of ‘weak’ decomposers (e.g., yeasts), but this response was reversed with Mn amendment, suggesting that higher Mn availability may promote fungal communities better adapted to decompose lignin. We conclude that Mn limitation may represent a mechanism to explain shifts in fungal communities, reduced litter decomposition, and increased soil C accumulation under long-term atmospheric N deposition.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Atwood2018,

title = {Evidence for multi-trophic effects of pesticide seed treatments on non-targeted soil fauna},

author = {Lesley W. Atwood and David A. Mortensen and Roger T. Koide and Richard G. Smith},

doi = {10.1016/j.soilbio.2018.07.007},

issn = {00380717},

year  = {2018},

date = {2018-10-01},

journal = {Soil Biology and Biochemistry},

volume = {125},

pages = {144–155},

publisher = {Elsevier Ltd},

abstract = {The use of pesticide seed treatments containing neonicotinoid insecticides is widespread in large-scale row crop agriculture. Recently, use of pesticide seed treatments has come under scrutiny due to concerns over non-target impacts on beneficial insects (e.g., honey bees) and the environment. Amidst these growing concerns, however, few studies have examined how pesticide seed treatments may impact soil faunal communities across multiple feeding guilds and the soil processes they regulate. We grew corn and soybean with and without pesticide seed treatment for three years and measured the response of the soil faunal detritivore, herbivore, mixed, and predator feeding guilds, nitrogen mineralization, and surface litter decomposition at three time points each year. We found the effects of seed treatment on the soil faunal community varied in direction and magnitude by year and feeding guild and were most apparent in the predator and detritivore guilds. Guild-level effects tended to be strongest soon after planting but remained apparent throughout the crop growing season, particularly in the predator and mixed feeding guilds. We found no evidence that pesticide seed treatment affected the herbivore guild—the intended target of the seed treatment, or nitrogen mineralization, surface litter decomposition, or grain yields. Collectively, these data suggest that pesticide seed treatments can alter the abundance, richness, and diversity of all non-targeted soil faunal guilds. Additional research will be necessary to determine the longer-term significance of pesticide seed treatment-driven changes in non-target soil faunal communities in agroecosystems.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Jilling2018,

title = {Minerals in the rhizosphere: overlooked mediators of soil nitrogen availability to plants and microbes},

author = {Andrea Jilling and Marco Keiluweit and Alexandra R. Contosta and Serita Frey and Joshua Schimel and Jörg Schnecker and Richard G. Smith and Lisa Tiemann and A. Stuart Grandy},

doi = {10.1007/s10533-018-0459-5},

issn = {1573515X},

year  = {2018},

date = {2018-07-01},

journal = {Biogeochemistry},

volume = {139},

number = {2},

pages = {103–122},

publisher = {Springer International Publishing},

abstract = {Despite decades of research progress, ecologists are still debating which pools and fluxes provide nitrogen (N) to plants and soil microbes across different ecosystems. Depolymerization of soil organic N is recognized as the rate-limiting step in the production of bioavailable N, and it is generally assumed that detrital N is the main source. However, in many mineral soils, detrital polymers constitute a minor fraction of total soil organic N. The majority of organic N is associated with clay-sized particles where physicochemical interactions may limit the accessibility of N-containing compounds. Although mineral-associated organic matter (MAOM) has historically been considered a critical, but relatively passive, reservoir of soil N, a growing body of research now points to the dynamic nature of mineral-organic associations and their potential for destabilization. Here we synthesize evidence from biogeoscience and soil ecology to demonstrate how MAOM is an important, yet overlooked, mediator of bioavailable N, especially in the rhizosphere. We highlight several biochemical strategies that enable plants and microbes to disrupt mineral-organic interactions and access MAOM. In particular, root-deposited low-molecular-weight exudates may enhance the mobilization and solubilization of MAOM, increasing its bioavailability. However, the competitive balance between the possible fates of N monomers—bound to mineral surfaces versus dissolved and available for assimilation—will depend on the specific interaction between mineral properties, soil solution, mineral-bound organic matter, and microbes. Building off our emerging understanding of MAOM as a source of bioavailable N, we propose a revision of the Schimel and Bennett (Ecology 85:591–602, 2004) model (which emphasizes N depolymerization), by incorporating MAOM as a potential proximal mediator of bioavailable N.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Smith2018,

title = {Environmental Correlates with Germinable Weed Seedbanks on Organic Farms across Northern New England},

author = {R. G. Smith and S. K. Birthisel and S. C. Bosworth and B. Brown and T. M. Davis and E. R. Gallandt and A. Hazelrigg and E. Venturini and N. D. Warren},

doi = {10.1017/wsc.2017.40},

issn = {15502759},

year  = {2018},

date = {2018-01-01},

journal = {Weed Science},

volume = {66},

number = {1},

abstract = {textcopyright 2017 Weed Science Society of America. The northern New England region includes the states of Vermont, New Hampshire, and Maine and encompasses a large degree of climate and edaphic variation across a relatively small spatial area, making it ideal for studying climate change impacts on agricultural weed communities. We sampled weed seedbanks and measured soil physical and chemical characteristics on 77 organic farms across the region and analyzed the relationships between weed community parameters and select geographic, climatic, and edaphic variables using multivariate procedures. Temperature-related variables (latitude, longitude, mean maximum and minimum temperature) were the strongest and most consistent correlates with weed seedbank composition. Edaphic variables were, for the most part, relatively weaker and inconsistent correlates with weed seedbanks. Our analyses also indicate that a number of agriculturally important weed species are associated with specific U.S. Department of Agriculture plant hardiness zones, implying that future changes in climate factors that result in geographic shifts in these zones will likely be accompanied by changes in the composition of weed communities and therefore new management challenges for farmers.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Cordeau2017,

title = {How do weeds differ in their response to the timing of tillage? A study of 61 species across the northeastern United States},

author = {S. Cordeau and R. G. Smith and E. R. Gallandt and B. Brown and P. Salon and A. DiTommaso and M. R. Ryan},

url = {http://doi.wiley.com/10.1111/aab.12377},

doi = {10.1111/aab.12377},

issn = {00034746},

year  = {2017},

date = {2017-11-01},

journal = {Annals of Applied Biology},

volume = {171},

number = {3},

pages = {340–352},

publisher = {Blackwell Publishing Ltd},

abstract = {Previous research has demonstrated that the season in which soil is tilled (spring versus fall) can strongly influence weed community assembly and subsequent species composition and abundance in annual cropping systems. Despite this understanding, it is unknown whether finer-scale, within-season variation in the timing of tillage has similar impacts on weed community assembly. We conducted an experiment on four research farms across the northeastern USA to test the effects of tillage timing on weed emergence periodicity. Soil was tilled at 12 different times that were 2 weeks apart from 29 April to 30 September (the entire growing season) and the composition and abundance of the weed seedlings that emerged was measured 6 weeks later. Weed species clustered into three tillage timing groups at the two New York locations and clustered into five tillage timing groups at the New Hampshire and Maine locations. Individual species associated with each window of tillage time varied by location. No single trait or combination of traits were consistently associated with species-by-tillage time groupings across locations; however, within each location several traits were associated with particular groups of species, including: (a) seed length, (b) seed weight, (c) cotyledon type, (d) life span, (e) ploidy level and (f) photosynthetic pathway. These results suggest that fine-scale variation in the timing of tillage can lead to predictable changes in the species composition and trait distribution of weed communities in annually tilled agroecosystems.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Cordeau2017b,

title = {Disentangling the Effects of Tillage Timing and Weather on Weed Community Assembly},

author = {Stéphane Cordeau and Richard Smith and Eric Gallandt and Bryan Brown and Paul Salon and Antonio DiTommaso and Matthew Ryan},

url = {http://www.mdpi.com/2077-0472/7/8/66},

doi = {10.3390/agriculture7080066},

issn = {2077-0472},

year  = {2017},

date = {2017-08-01},

journal = {Agriculture},

volume = {7},

number = {8},

pages = {66},

publisher = {MDPI AG},

abstract = {The effect of tillage timing on weed community assembly was assessed at four locations in the Northeastern United States by tilling the soil every two weeks from April to September and quantifying the emerged weed community six weeks after each tillage event. Variance partitioning analysis was used to test the relative importance of tillage timing and weather on weed community assembly (106 weed species). At a regional scale, site (75.5% of the explained inertia)—and to a lesser extent, timing—of tillage (18.3%), along with weather (18.1%), shaped weed communities. At a local scale, the timing of tillage explained approximately 50% of the weed community variability. The effect of tillage timing, after partitioning out the effect of weather variables, remained significant at all locations. Weather conditions, mainly growing degree days, but also precipitation occurring before tillage, were important factors and could improve our ability to predict the impact of tillage timing on weed community assemblages. Our findings illustrate the role of disturbance timing on weed communities, and can be used to improve the timing of weed control practices and to maximize their efficacy.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Cordeau2017a,

title = {Timing of Tillage as a Driver of Weed Communities},

author = {Stéphane Cordeau and Richard G. Smith and Eric R. Gallandt and Bryan Brown and Paul Salon and Antonio DiTommaso and Matthew R. Ryan},

doi = {10.1017/wsc.2017.26},

issn = {15502759},

year  = {2017},

date = {2017-07-01},

journal = {Weed Science},

volume = {65},

number = {4},

pages = {504–514},

publisher = {Cambridge University Press},

abstract = {Tillage is a foundational management practice in many cropping systems. Although effective at reducing weed populations and preparing a crop seedbed, tillage and cultivation can also dramatically alter weed community composition. We examined the impact of soil tillage timing on weed community structure at four sites across the northeastern United States. Soil was tilled every 2 wk throughout the growing season (late April to late September 2013), and weed seedling density was quantified by species 6 wk after each tillage event. We used a randomized complete block design with four replicates for each tillage-timing treatment; a total of 196 plots were sampled. The timing of tillage was an important factor in shaping weed community composition and structure at all sites. We identified three main periods of tillage timing that resulted in similar communities. Across all sites, total weed density tended to be greatest and weed evenness tended to be lowest when soils were tilled early in the growing season. From the earliest to latest group of timings, total abundance decreased on average from 428textpm393 to 159textpm189 plants m-2, and evenness increased from 0.53textpm0.25 to 0.72textpm0.20. The effect of tillage timing on weed species richness varied by site. Our results show that tillage timing affects weed community structure, suggesting that farmers can manage weed communities and the potential for weed interference by adjusting the timing of their tillage and cropping practices.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Schipanski2017,

title = {Balancing multiple objectives in organic feed and forage cropping systems},

author = {Meagan E. Schipanski and Mary E. Barbercheck and Ebony G. Murrell and Jayson Harper and Denise M. Finney and Jason P. Kaye and David A. Mortensen and Richard G. Smith},

doi = {10.1016/j.agee.2017.01.019},

issn = {01678809},

year  = {2017},

date = {2017-02-01},

journal = {Agriculture, Ecosystems and Environment},

volume = {239},

pages = {219–227},

publisher = {Elsevier B.V.},

abstract = {Balancing weed suppression, beneficial insect conservation, soil quality and profitability is challenging in organic cropping systems due to reliance on soil disturbance for weed control. We hypothesized that the benefits of tillage can be retained while mitigating adverse impacts on soil quality by alternating tillage with practices that can build soil organic matter. We conducted a four-year experiment in central Pennsylvania, USA, to compare four organic feed and forage cropping systems, each differing in tillage, manure management, and cropping strategies. Each system was designed to address baseline soil quality and weed pressure conditions arising from practices implemented during the previous three-year transition period. To assess cumulative system effects, we established a soybean (Glycine max) uniformity trial across all systems in year four. Systems that were in perennial forage for 2 years outperformed annual crop-based systems in weed control and beneficial insect conservation, while maintaining overall profitability over the four-year study period. Soybean yields during the uniformity trial were more than 30% greater in systems that had included perennial forages than in systems with only annual crops. Labile soil carbon pools, an indicator of soil quality, were maintained over time in all systems. Our results indicate that soil quality, weed management, beneficial insect conservation, and profitability can be maintained in organic systems when periodic tillage is coupled with perennial forage crops in rotation.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Hunter2017,

title = {Agriculture in 2050: Recalibrating Targets for Sustainable Intensification},

author = {Mitchell C Hunter and Richard G Smith and Meagan E Schipanski and Lesley W Atwood and David A Mortensen},

url = {http://bioscience.oxfordjournals.org},

doi = {10.1093/biosci/bix010},

year  = {2017},

date = {2017-01-01},

journal = {BioScience},

volume = {386},

number = {4},

abstract = {The prevailing discourse on the future of agriculture is dominated by an imbalanced narrative that calls for food production to increase dramatically-potentially doubling by 2050-without specifying commensurate environmental goals. We aim to rebalance this narrative by laying out quantitative and compelling midcentury targets for both production and the environment. Our analysis shows that an increase of approximately 25%-70% above current production levels may be sufficient to meet 2050 crop demand. At the same time, nutrient losses and greenhouse gas emissions from agriculture must drop dramatically to restore and maintain ecosystem functioning. Specifying quantitative targets will clarify the scope of the challenges that agriculture must face in the coming decades, focus research and policy on achieving specific outcomes, and ensure that sustainable intensification efforts lead to measurable environmental improvements. We propose new directions for research and policy to help meet both sustainability and production goals.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Williams2017,

title = {Reconciling opposing soil processes in row-crop agroecosystems via soil functional zone management},

author = {Alwyn Williams and Adam S. Davis and Andrea Jilling and A. Stuart Grandy and Roger T. Koide and David A. Mortensen and Richard G. Smith and Sieglinde S. Snapp and Kurt A. Spokas and Anthony C. Yannarell and Nicholas R. Jordan},

doi = {10.1016/j.agee.2016.11.012},

issn = {01678809},

year  = {2017},

date = {2017-01-01},

journal = {Agriculture, Ecosystems and Environment},

volume = {236},

pages = {99–107},

publisher = {Elsevier B.V.},

abstract = {Sustaining soil productivity in agricultural systems presents a fundamental agroecological challenge: nutrient provisioning depends upon aggregate turnover and microbial decomposition of organic matter (SOM); yet to prevent soil depletion these processes must be balanced by those that restore nutrients and SOM (soil building processes). These nutrient provisioning and soil building processes are inherently in conflict; management practices that create spatial separation between them may enable each to occur effectively within a single growing season, thereby supporting high crop yield while avoiding soil depletion. Soil functional zone management (SFZM), an understudied but increasingly adopted strategy for annual row-crop production, may help meet this agroecological challenge by creating spatial heterogeneity in biophysical conditions between crop rows and inter-rows. However, the process-level effects of this spatial heterogeneity on nutrient provisioning and soil building processes have not been characterised. We assessed the magnitude and spatial distribution of nutrient provisioning and soil building processes in model SFZM (ridge tillage) and conventional tillage (chisel plough) systems in four US states encompassing a major global agricultural production region. For soil building we measured bulk density, aggregation and permanganate oxidisable carbon (POXC); for nutrient provisioning we measured microbial decomposition activity, nutrient mineralisation and plant-available nitrogen. After two years, POXC increased under ridge tillage (0–20 cm depth) compared with chisel plough. Ridge tillage also enhanced nutrient provisioning processes in crop rows, increasing plant-available nitrogen in synchrony with maize peak nitrogen demand. Structural equation modelling revealed that improvement in soil building processes under ridge tillage caused rapid enhancement of nutrient provisioning processes in SOM-poor soils. Increases in crop row POXC stimulated microbial decomposition activity, which was associated with increased plant-available nitrogen during the phase of maize peak nitrogen demand. The decimetre-scale spatial heterogeneity created by ridge tillage enables reconciliation of nutrient provisioning and soil building processes in row-crop agroecosystems. In doing so, ridge tillage promotes critical soil processes necessary for increasing the range of ecosystem services provided by intensive production systems. SFZM approaches may have particular value in regions with SOM-poor soils, which would benefit from rapid increases in surface organic carbon. Also, by concentrating and promoting nutrient provisioning processes around crop roots during crop peak nitrogen demand, ridge tillage may enhance nitrogen-use efficiency and reduce current fertiliser requirements.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Soil and understory plant dynamics during conversion of forest to silvopasture, open pasture, and woodlot},

author = {Joseph Orefice; Richard G. Smith; John Carroll; Heidi Asbjornsen; Daniel Kelting },

doi = {https://doi.org/10.1007/s10457-016-0040-y},

year  = {2017},

date = {2017-00-00},

urldate = {2017-00-00},

journal = {Agroforestry Systems},

number = {91},

pages = {729-739},

abstract = {Little is known regarding the impact of converting northern hardwood forests to pasture or silvopasture. Our objective was to investigate how understory plant communities and soil physical and chemical properties respond during the first 2 years following conversion of northern hardwood forest to pasture. To accomplish this, we established three forest conversion treatments (silvopasture, open pasture, and woodlot) in a 50 year old northern hardwood forest in New York. The silvopasture and open pasture treatments were seeded with forages and then grazed with cattle after the initial timber harvest. Understory plant inventories and soil sampling were conducted pre-treatment and 2 years after treatment establishment. Understory non-woody plant species richness increased in all treatments during the two year period (F = 73.633, P < 0.001), while species richness of understory woody plants remained similar to pretreatment levels (F = 2.648, P = 0.150). Species most negatively affected by forest conversion included Arisaema triphyllum, Mitchella repens, and Thalictrum pubescens. Species that were only observed after the treatments were established included Danthonia spicata, Agrostis spp., Ranunculus spp., Digitaria spp., Rumex acetosella, and Hieracium spp. One species, Vaccinium angustifolium, was negatively affected by the silvopasture and open pasture treatments, but not the woodlot treatment. Soil bulk density was higher in both the open and silvopasture treatments compared to pretreatment levels, but the woodlot treatment soil bulk density remained statistically similar to pre-treatment levels. Percent total nitrogen, potentially mineralizable nitrogen, and phosphorus increased in silvopastures, open pastures, and woodlot treatment groups compared to pre-treatment levels. Future research should investigate the implications of these changes in ecosystem structure and composition.

},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Menalled2016,

title = {The Eco-Evolutionary Imperative: Revisiting Weed Management in the Midst of an Herbicide Resistance Crisis},

author = {Fabian Menalled and Robert Peterson and Richard Smith and William Curran and David Páez and Bruce Maxwell},

url = {http://www.mdpi.com/2071-1050/8/12/1297},

doi = {10.3390/su8121297},

issn = {2071-1050},

year  = {2016},

date = {2016-12-01},

journal = {Sustainability},

volume = {8},

number = {12},

pages = {1297},

publisher = {MDPI AG},

abstract = {Modern weed science is at a crossroads. Born out of advances in chemistry, it has focused on minimizing weed competition with genetically uniform crops and heavy reliance on herbicides. Paradoxically, the success obtained with such an approach and the reluctance to conduct integrated and multidisciplinary research has resulted in unintended, but predictable, consequences, including the selection of herbicide resistant biotypes. Advances in eco-evolutionary biology, a relatively recent discipline that seeks to understand how local population dynamics arise from phenotypic variation resulting from natural selection, habitat distribution, and propagule dispersal across the landscape are transforming our understanding of the processes that regulate agroecosystems. Within this framework, complementary tactics to develop alternative weed management programs include the following: (1) weed scientists must recognize that evolution occurs within crop fields at ecologically-relevant time scales and is rooted in the inherent variation that exists in all populations; (2) weed management should recognize that the probability of a resistant mutant is directly related to the population size; (3) farmers need to acknowledge that herbicide resistance transcends any one farm and should coordinate local practices with regional actions; (4) incentives should be developed and implemented to help the adoption of eco-evolutionary management programs; and (5) risk analysis can help incorporate an eco-evolutionary perspective into integrated weed management programs.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Williams2016b,

title = {Enhanced control of soil nitrogen cycling through soil functional zone management},

author = {Alwyn Williams and Patrick M. Ewing and Nicholas R. Jordan and Adam S. Davis and A. Stuart Grandy and Richard G. Smith and Daniel A. Kane and Sieglinde S. Snapp and Roger T. Koide and David A. Mortensen and Kurt A. Spokas and Anthony C. Yannarell},

url = {http://doi.wiley.com/10.2134/cs2016-49-0602},

doi = {10.2134/cs2016-49-0602},

issn = {01625098},

year  = {2016},

date = {2016-11-01},

journal = {Crops & Soils},

volume = {49},

number = {6},

pages = {42–45},

publisher = {Wiley},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Williams2016a,

title = {Precision control of soil nitrogen cycling via soil functional zone management},

author = {Alwyn Williams and Adam S. Davis and Patrick M. Ewing and A. Stuart Grandy and Daniel A. Kane and Roger T. Koide and David A. Mortensen and Richard G. Smith and Sieglinde S. Snapp and Kurt A. Spokas and Anthony C. Yannarell and Nicholas R. Jordan},

doi = {10.1016/j.agee.2016.07.010},

issn = {01678809},

year  = {2016},

date = {2016-09-01},

journal = {Agriculture, Ecosystems and Environment},

volume = {231},

pages = {291–295},

publisher = {Elsevier B.V.},

abstract = {Managing the soil nitrogen (N) cycle is a major component of agricultural sustainability. Soil functional zone management (zonal management) is a novel agroecological strategy for managing row-crop agroecosystems. It may improve the efficiency of soil N cycling compared with conventional and no-tillage approaches, by managing the timing and location (crop row vs inter-row) of key soil N cycling processes. We compared N mineralization and availability during the period of maize peak N demand in crop rows and inter-rows in zonal management and conventional chisel plow tillage systems at four sites across the US Corn Belt over three growing seasons. Under zonal management, potential N mineralization and N availability during crop peak N demand were significantly greater in crop rows, where the majority of crop roots are found, compared with inter-rows. Averaged across all site-years, plant-available N in zonal management crop rows was 46~mg~kg-1 compared with 21~mg~kg-1 in inter-rows. In contrast, in conventional tillage, potential N mineralization and N availability were greater in inter-rows compared with crop rows; averaged across all site-years, plant-available N in conventional tillage crop rows was 24~mg~kg-1 compared with 51~mg~kg-1 in inter-rows. The results demonstrate that the active management of crop residues under zonal management can enhance the spatiotemporal efficiency of soil N cycling processes, by concentrating N mineralization and availability close to crop roots in synchrony with crop developmental needs. Zonal management therefore has potential to increase crop N-use efficiency compared with conventional tillage, and thereby reduce the impacts of row-crop agricultural production on water resources and greenhouse gas emissions that result from N leaching and denitrification.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Jabbour2016,

title = {Cover crop and tillage intensities alter ground-dwelling arthropod communities during the transition to organic production},

author = {Randa Jabbour and Tara Pisani-Gareau and Richard G. Smith and Christina Mullen and Mary Barbercheck},

doi = {10.1017/S1742170515000290},

issn = {17421713},

year  = {2016},

date = {2016-08-01},

journal = {Renewable Agriculture and Food Systems},

volume = {31},

number = {4},

pages = {361–374},

publisher = {Cambridge University Press},

abstract = {We conducted a cropping systems experiment in central Pennsylvania, USA, to determine the effects of initial cover crop species and soil management on the abundance and composition of the ground-dwelling arthropod community. We hypothesized that we would detect legacy effects of the cover crops planted in year 1 of a 3-yr crop sequence on the arthropod community in the subsequent 2 yrs, and that these effects would be influenced by the intensity of tillage. We compared four systems in a factorial combination of perennial sod and legumes or annual cereal grain and legume as initial cover crops and moldboard or chisel plow tillage implemented in soybeans followed by maize in the subsequent 2 yrs. The entire experiment was initiated twice in adjacent locations, starting in 2003 (Start 1) and 2004 (Start 2). We quantified soil arthropod activity-density and community composition and identified all arthropods to order or family, and the ground and tiger beetles (Coleoptera: Carabidae) to species. In Start 1, but not Start 2, arthropod activity-density increased with each year following implementation of organic management. We observed few legacy effects of cover crop or tillage intensity on arthropod activity-density. The composition of the soil arthropod community was primarily defined by the initial cover crop in the first year, and by the interaction between cover crop and tillage intensity in the second and third year. A legacy effect associated with a yr-1 cover crop of cereal rye was observed for Scarabaeidae beetles and Formicidae (ants) in yr 2 and Carabidae beetles in yr 3 of Start 1, but not Start 2. Weed indicators contributed significantly to the variation in the soil arthropod community that was explained by the environment in yr 2 in Start 1, and in yr 3 in both Starts. Our observations support the concept that both immediate and legacy effects of management shape arthropod communities during the organic transition period, suggesting that transitioning systems could be managed in ways that conserve or enhance natural enemy populations.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Williams2016c,

title = {Soil water holding capacity mitigates downside risk and volatility in US rainfed maize: Time to invest in soil organic matter?},

author = {Alwyn Williams and Mitchell C. Hunter and Melanie Kammerer and Daniel A. Kane and Nicholas R. Jordan and David A. Mortensen and Richard G. Smith and Sieglinde Snapp and Adam S. Davis},

doi = {10.1371/journal.pone.0160974},

issn = {19326203},

year  = {2016},

date = {2016-08-01},

journal = {PLoS ONE},

volume = {11},

number = {8},

publisher = {Public Library of Science},

abstract = {Yield stability is fundamental to global food security in the face of climate change, and better strategies are needed for buffering crop yields against increased weather variability. Regional- scale analyses of yield stability can support robust inferences about buffering strategies for widely-grown staple crops, but have not been accomplished. We present a novel analytical approach, synthesizing 2000-2014 data on weather and soil factors to quantify their impact on county-level maize yield stability in four US states that vary widely in these factors (Illinois, Michigan, Minnesota and Pennsylvania). Yield stability is quantified as both ’downside risk’ (minimum yield potential, MYP) and ’volatility’ (temporal yield variability). We show that excessive heat and drought decreased mean yields and yield stability, while higher precipitation increased stability. Soil water holding capacity strongly affected yield volatility in all four states, either directly (Minnesota and Pennsylvania) or indirectly, via its effects on MYP (Illinois and Michigan). We infer that factors contributing to soil water holding capacity can help buffer maize yields against variable weather. Given that soil water holding capacity responds (within limits) to agronomic management, our analysis highlights broadly relevant management strategies for buffering crop yields against climate variability, and informs region-specific strategies.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}