The weed species Spermacoce densiflora DC. and Spermacoce verticillata L. have shown an increase in their occurrence in cultivated areas in the northeast region of Brazil, and field observations have reported their ineffective control with chemicals. This study aimed to evaluate the germination of S. densiflora and S. verticillata under constant (15, 20, 25, 30 and 35°C) and alternating temperatures (20–30°C) in dark and in constant light; the emergence of seedlings from seven sowing depths (0, 0.5, 1, 2, 4, 6 and 10 cm); the emergence of seedlings under five types of cover crop straw (Crotalaria juncea L., Pennisetum glaucum (L.) R. Br., Sorghum bicolor (L.) Moench, Dolichos lablab L., and Cajanus cajan L.) and four amounts (nil and the average, half and twice the amount of straw produced in the field); and germination at different aqueous cover crop extract concentrations (0, 20, 40, 60 and 100%) to measure allelopathic potential of cover crop straw. The results showed that S. densiflora has positive photoblastic behavior. The alternating temperature provided the highest percentage of germination and germination speed index (GSI) for both species. S. densiflora and S. verticillata seedling emergence decreased with an increase in depth, with no germination at a depth of 10 cm. The presence of straw impaired the emergence of seedlings of S. densiflora and S. verticillata by delaying and even preventing germination from occurring. The gradual increase in the aqueous extract concentrations was accompanied by lower percentages of germination and GSI for S. densiflora and S. verticillata.

Perennial grain crops are emerging as a promising addition to sustainable agricultural systems because of their low-input requirements and delivery of ecosystem services. However, adoption of these crops is expected to bring novel management challenges, including those related to plant diseases. In New York, fungal pathogens of annual grains have a significant impact on crop yield and value and are generally controlled through a combination of host resistances, cultural practices and chemical fungicides. Without the availability of crop rotation and soil tillage practices, disease control in perennial grain systems may be problematic, and little is known about perennial grain crop susceptibility to local plant pathogen populations. During 2017 and 2018, ongoing field trials of two perennial grain crops recently introduced in New York, intermediate wheatgrass (IWG; Thinopyrum intermedium) and perennial cereal rye (PCR; Secale cereale), were assessed for the presence of putative fungal pathogens on actively growing plants, overwintered crop residue and harvested grain. A total of nine potential host–pathogen combinations were recorded based on symptomology, pathogen morphology and DNA sequences. Common annual crop pathogens were recovered most frequently, but, at one site, Phyllachora graminis, causal fungus of tar spot and a pathogen not previously reported on crops in New York, was found on IWG. Residue colonization by an important toxigenic pathogen (Fusarium graminearum) was high in both crops, though mycotoxin levels in associated grain were low, indicating either the hosts or environment were unsuitable for disease development. Seed-borne fungal communities differed across crops and locations, and black point, a condition caused by Alternaria and Bipolaris fungi and indicative of compromised grain quality, was prevalent in PCR under some conditions. Growing PCR with intercropped red clover (Trifolium pratense L.) resulted in less Stagonospora colonization of stem residue, and PCR grown with an oat (Avena sativa L.) nurse crop had a reduced incidence of black point. These alternative cultural practices may prove useful for managing disease in perennial grains. Our results suggest that the incorporation of perennial crops into the agricultural landscape will lead to familiar plant disease problems requiring new solutions as well as new problems that may require significant research investments.

Across the Midwest, substantial funding and personnel time have been allocated to encourage farmers to adopt a wide range of conservation practices but adoption rates for many of these practices remain low. Prior research focuses largely on the influence of individual-level factors (e.g., beliefs, attitudes) on conservation practice adoption rather than on contextual factors (e.g., seasons) that might also play a role. In the present study, we considered seasonal variation and its potential influence on farmer cover crop decision-making. We first established how farmer temporal and financial resources fluctuate across the year and then compared the annual agricultural decision and cover crop decision calendars. We also considered farmer cover crop perceptions and likely behaviors. To study this, we surveyed the same Midwestern farmers in the spring, summer and winter within a 12-month period. Results indicated that farmers were generally the least busy and the most financially comfortable in the winter months. Moreover, farmers perceived the benefits of cover crops differently throughout the year. These results indicate that seasonality can be a confounding factor which should be considered when designing and conducting research and farmer engagement. As researchers, it is our responsibility to understand the specific calendar experienced by our sample and how that may influence responses so we can examine theory-supported factors of interest rather than seasonality as a driver of farmer responses. As practitioners, it is important to use research findings to engage with farmers about conservation in a way that prioritizes communicating about the most salient aspects of the practice at the time of year when farmers will be most receptive.

Although research has demonstrated the positive nutritional value and environmental benefits associated with edible insect consumption, several factors challenge the growth and development of the edible insect industry for human consumption in the US and Canada. Cultural and psychological factors account for much of the aversion US and Canadian consumers display. The absence of specific regulation also constitutes a structural barrier to more widespread production and sale of edible insects. Compared to the US, the European Union has a more developed edible insect industry and has enacted legislation that removes some of the barriers. As consumer awareness of the putative health benefits of edible insects increases, more comprehensive regulations may emerge to keep pace with the growth of this industry. Overall, a multi-disciplinary approach that addresses both benefits and barriers to consumption is needed to facilitate a robust market for edible insects in the US and Canada.

The diversity and distribution of wild bees are dramatically changing due to habitat fragmentation, agricultural intensification and climate change. In cities, urban gardens are proposed ‘island’ habitats for bees offering floral and nesting resources. Yet, it is largely unclear how gardens play a role in changes in species diversity and distribution. This paper reports on the discovery of a bee species to our knowledge previously undocumented in the region of Berlin, Germany. We discovered Lasioglossum limbellum in a community garden created on concrete slabs of annual and perennial vegetation. As a cavity nester in soft rock cliffs—a natural habitat functionally not existent in urban areas—the life history of this species makes this discovery particularly interesting, and an opportunity to explore the role of urban gardens in biodiversity change. This report aims to spur future research, reporting and discussion on the changes in diversity and distribution of wild bees specifically in urban areas.

Intensive vegetable crop rotations can have detrimental effects on soil health, draining soil of organic matter reserves and necessitating nitrogen (N) inputs. In addition, many vegetable crop rotations leave little time or space to integrate beneficial arthropod and pollinator habitat into crop rotations; the lack of habitat may cause declines in beneficial arthropods, which can lead to insufficient pollination services and increased pest pressure. Nine treatments, each containing one to seven species of cover crops, were evaluated for flowering, aboveground biomass production and N content, soil ${\rm NO}_3^-$-N contribution after biomass incorporation, and beneficial arthropod visitation. A seven-species mix composed of oat (Avena sativa L.), field pea (Pisum sativum subsp. Arvense L.) and five clover species (Trifolium spp.) added the largest amount of biomass (8747 kg ha−1). Likewise, this mix contributed the most organic N (265.6 kg N ha−1), and increased soil ${\rm NO}_3^-$-N after biomass incorporation (10.9 mg ${\rm NO}_3^-$-N kg−1 of soil). Buckwheat (Fagopyrum esculentum Moench) and phacelia (Phacelia tanacetifolia Bendth.) monoculture produced most abundant floral resources. Beneficial arthropods observed included pollinators (native, honey and bumblebees), predators (syrphid flies and green lacewings) and parasitoids. Increased floral diversity was associated with abundance of flies in the Syrphidae family. Phacelia monoculture was most attractive for bees in the Apidae and Halictidae family, both of which may provide pollination services. These results highlight floral visitation patterns as an indicator for beneficial insect community support and conservation, especially in summer months, when greater insect reproduction occurs. Summer-planted cover crops are an underexplored rotation option for organic farming systems in the Upper Midwest, and may provide a wide range of ecosystem services including increases in available soil N and beneficial arthropod populations.

Crops emit a variety of volatile organic compounds (VOCs) that serve as attractants or repellents for pests and their natural enemies. Crop rotations, off-farm chemical inputs, and mechanical and cultural tactics – collectively called cropping systems – alter soil nutrients, moisture content, and microbial communities, all of which have the potential to alter crop VOC emissions. Soil legacy effects of diversified cropping systems have been shown to enhance crop VOC emissions in greenhouse studies, but how they influence emissions under field conditions remains virtually unknown. To determine the effect of cropping systems on plant VOC emissions in the field, air samples were collected from the headspace of wheat (Triticum aestivum L. Judee) grown in simplified wheat-fallow rotations or diversified wheat-cover crop rotations where cover crops were terminated by grazing cattle. Across two growing seasons, wheat grown in rotation with fallow emitted greater amounts of Z-3-hexenyl acetate and β-ocimene, key attractants for wheat stem sawfly (Cephus cinctus Norton), a major pest of wheat. While overall VOC blends were relatively similar among cropping system during the first growing season, emissions varied substantially in the second year of this study where wheat grown in rotation with cover crops emitted substantially greater quantities of volatile compounds characteristic of abiotic stress. Below-average precipitation in the second growing season, in addition to reduced soil water content in cover crop rotations, suggests that cropping system effects on wheat VOCs may have been driven primarily by water availability, a major factor limiting crop growth in dryland agriculture. While the specific mechanisms driving changes in VOC emissions were not explicitly tested, this work shows that agricultural practices applied in one growing season can differentially influence crop VOC emissions in the next through soil legacy effects, illustrating additional avenues through which cropping systems may be leveraged to enhance pest management.

Faced with a society that demands the reduction of negative environmental impacts of agriculture while producing high-value, healthy food for local and export markets, Argentina is currently in a debate on the alternative paths toward sustainability in agricultural production. Argentina is ranked second in the world in terms of land under organic certification. Extensive sheep production in Patagonia natural grasslands accounts for most of this area and harvested organic area remains a very small fraction of total harvested land (0.6%). This paper aims to contribute to the discussion of opportunities and limitations in organic farming as an ecological intensification alternative for Argentina's Pampas. A case study was conducted on Pampa Orgánica Norte. This is a group of nine organic farmers that manages field crops and livestock-certified organic production. Farmers interviewed in this study considered different criteria including economic and environmental attributes when choosing to produce organically. However, the main drivers for conversion to organic production are related to environmental factors, in particular ecosystem protection. The main limitations in organic production are related to crop management practices, primarily weed control. To achieve the goal of increasing organic production a more active role of the public sector in technology generation and transfer was demanded by farmers.

Improving fertilizer use efficiency has remained a challenge, particularly for small-scale farming in undulating ‘abnormal’ landscapes of East Africa. Milne's 1930s concept on ‘Catena’ was considered as a breakthrough in understanding soil variability and its implication on productivity in East African highlands. However, there is limited information on how the ‘Catena’ features could be used for fine tuning fertilizer recommendations. We initiated multiple on-farm replicated experiments in three wheat-growing districts (Endamohoni, Lemo and Worreilu) in the Ethiopian highlands in 2014, 2015 and 2016 to assess landscape positions affecting crop-nutrient responses, identify yield limiting nutrients across the ‘Catena’ (N, P, K, S and Zn) and quantify effects of landscape positions on resources use efficiency. We clustered farmlands across the ‘Catena’ (Hillslopes, Midslopes and Footslopes) based on land scape positions in the respective locations. Wheat yield was more strongly and significantly affected by landscape positions (P < 0.001) than by nutrient sources or rates. The crop response to fertilizers was 50 to 300% higher in foot slopes than in hillslopes, depending on locations and inputs levels. With increasing slope, there was a decrease in a crop fertilizer response due to a significant decrease in soil organic carbon, clay content and soil water content, with r2 of 0.95, 0.86 and 0.96, respectively. The difference in the crop response between landscape positions was significantly higher (P < 0.05) with higher rates of nutrient applications (>N92 P46) while differences between landscape positions diminish at lower rates. Yield benefits due to application of K was significant only in the dry years (P < 0.05), while there was hardly any yield benefit from the application of zinc and sulfur. The crop nitrogen recovery fraction and crop water productivity decreased with an increasing slope regardless of nutrient combinations. The results indicated that the landscape position could be considered as a proxy indicator for targeted fertilizer application, particularly in farms with undulating topographic features. Hillslopes are better served by the application of organic fertilizers along with conservation measures as applying higher rates of mineral fertilizer in hillslopes would rather increase the risk of downstream nutrient movement.

Crop-livestock integration has demonstrated that cover crops can be terminated using livestock grazing with minimal negative impacts on soil health, however, provides little information on system-level approaches that mutually benefit soil health and both crop and livestock production. Therefore, the objective of this research was to examine the effects of cover crop mixtures on biomass production, quality and the potential for nitrate toxicity on a dryland wheat-cover crop rotation. This research was conducted at the Montana State University-Northern Agricultural Research Center near Havre, MT (48°29′N, −109°48′W) from 2012 to 2019. This experiment was conducted as a randomized-complete-block design, where 29 individual species were utilized in 15 different cover crop mixtures in a wheat-cover crop rotation. Cover crop mixtures were classified into four treatment groups, including (1) cool-season species, (2) warm-season species dominant, (3) cool and warm-season species mixture (mid-season), and (4) a barley (Hordeum vulgare) control. All cover crop mixtures were terminated at anthesis of cool-season cereal species to avoid volunteer cereal grains in the following wheat crop. At the time of cover crop termination, dry matter forage production was estimated and analyzed for crude protein, total digestible nutrients and nitrates as indicators of forage quality. All mixtures containing oats (Avena sativa) had greater (P ⩽ 0.03) biomass production than other mixtures within their respective treatment groups (cool- and mid-season). Forage biomass was influenced by cover crop treatment group, with the barley producing the greatest (P < 0.01) amount of forage biomass when compared to cool-, mid- and warm-season cover crop treatments. Total digestible nutrients were greater (P < 0.01) in the barley control compared to the cool- and mid-season treatment groups. Crude protein was greatest in the warm-season treatment group (P < 0.01) compared to the barley control, cool- and mid-season treatment groups. The barley control produced fewer nitrates (P ⩽ 0.05) than the cool-, mid- and warm-season treatment groups; however, all cover crop mixtures produced nitrates at levels unsafe for livestock consumption at least one year of the study. The relatively high and variable nitrate levels of all cover crop mixtures across years in this study suggest that forage should be tested for nitrates before grazing. In conclusion, our research suggests that in a dryland wheat-cover crop rotation that requires early-July termination, cool-season cover crop mixtures are the most suitable forage source for livestock grazing most years.

This article offers a window onto the experience of three researchers who influenced the direction of organic agriculture research from the 1980s through today. Kathleen Delate, Catherine Greene and Deborah Stinner have all contributed important work in the field, from organizing and executing research projects to analyzing the collecting hard data that provided insight into the numerous environmental and economic benefits of organic agriculture. Their stories share many similar biographical markers, from the importance of food and nature in childhood memories to trailblazing projects in the early 2000s.

Declining nutrient densities of crops in the past 50–70 years have been attributed to unsound agricultural practices and plant breeding focus on yield rather than quality. Few studies have quantified the soil and nutritional quality of grains in organic and conventional farms and reported results are scarce and inconsistent. The Rodale Institute's Farming Systems Trial (FST) was established in 1981 to quantify the effects of long-term organic and conventional grain cropping systems and tillage practices. A 2014 study to quantify effects on the nutrient density of oat grains was integrated into three systems within the long-term trial: organic manure-based (MNR), organic legume-based (LEG), and conventional synthetic input-based (CNV), split between tilled (T) and no-till (NT) practices. Oat grains with hulls removed were analyzed for minerals (n = 24), vitamins (n = 24), amino acids (n = 24) and proteins (n = 24), while soil samples to a depth of 10 cm were analyzed for elemental minerals, and total carbon (C), nitrogen (N) and sulfur (S). Organic systems increased six out ten soil minerals whose concentrations were influenced by cropping systems: aluminum (Al), iron (Fe), chromium (Cr), calcium (Ca), barium (B) and strontium (Sr). All essential amino acids were greater in oat grains under LEG systems compared with other systems except lysine, histidine and methionine. Both LEG systems also increased 12 out of 13 non-essential amino acids in oat grains. Total oat N, C and S required for amino acid synthesis tended to be greater in organic systems. Soil N, C and S were highly correlated with total oat amino acids under organic systems compared to CNV. Organic LEG had significantly greater vitamin B1 than MNR and CNV. These results suggest that nutrient concentrations of oat grains were greater in organic systems compared to CNV systems, and the increase could be partially explained by the long-term soil management differences between the systems.

Biobased and biodegradable mulches (BDM) are a potentially sustainable alternative to polyethylene plastic mulch because they can be tilled into the soil at the end of the growing season. However, their degradation rate in the soil is uncertain, limiting their on-farm adoption. The objective of this study was to determine whether organic soil management practices could be leveraged to speed degradation of two potentially BDM across two diverse agroecoregions [Lincoln (LNK) and Scottsbluff (SBF), NE, USA]. Management treatments included compost, compost extract, cover crops, all three of these practices combined and a control. The two mulch types studied were a nonwoven polylactic acid fabric with embedded wood particles (PLA), and a starch-polyester mulch film (BLK). Mulches were applied in spring 2017 for vegetable production and removed in fall after harvest. Recovered mulch was sectioned into squares 10 cm2 and buried in mesh bags for 22 months. Mulch degradation, and soil chemical, physical and biological properties were measured at four times over 2 years. Management treatments applied seasonally across 2 years led to expected changes in soil properties, yet they had no effect on mulch degradation. Instead, mulch degradation was driven by the interaction of location and mulch type. The BLK mulch had degraded by 98% at LNK after 12 months, but only by half after 22 months at SBF. Degradation of PLA after 22 months was similar between locations with 29 ± 4% mulch mass remaining at SBF and 33 ± 4% remaining at LNK. Climate and soil characteristics at each location were strong determinants of mulch degradation. Specifically, soils at LNK were finer textured, lower in pH, higher in soil water content, organic matter and nitrates, and with greater bacterial abundance compared to SBF. The strong location by mulch type interaction observed could inform the development of regionally specific predictive models of degradation.

Afar in Ethiopia is a drought prone area characterized by low rainfall, high temperature and suffering from flash flood emerging from adjacent mountains. We introduced a flood barrier, water spreading weirs (WSWs) in 2015 to convert floods to a productive use and assessed its effect in 2016 and 2017. WSWs resulted in deposition of sediments where sand deposition was higher in the upside of upstream weir whereas silt and clay deposition was prominent at the central location between the two weirs. There was a moisture gradient across farming fields with volumetric water content (VWC) at 20 cm depth varying between 10 and 22% depending on the relative position/distance of fields from the WSWs, consequently, effecting significant difference in yield between fields. There was a positive relationship between VWC made available by WSWs at planting and the yield (P < 0.001, r = 0.76) and biomass productivity (P < 0.005, r = 0.46). WSWs created differing farming zone following soil moisture regime, affecting grain and biomass yield. In good potential zones with high moisture content, the WSW-based farming enabled to produce up to 5 and 15 t ha−1 yr−1 of maize grain and biomass, respectively, while in low potential zones there was a complete crop grain failure. The system enabled pastoralists to produce huge amount of biomass and grain during Belg (short) and Meher (long) growing seasons that was stored and utilized during succeeding dry periods. Furthermore, the practice ensured a visible recovery of degraded rangelands. This was evident from the filling up of the riverbed as well as the two WSW wings with 1 m high and about 450 m length each with fertile sediment from Belg and Meher seasons of 2016 and 2017. Hence, future studies should analyze the sustainability and the potential of flood-based development at large scale.

The US organic milk food system has several interesting characteristics. The product has been enthusiastically embraced by consumers, resulting in increased retail sales of organic milk. The processing sector is oligopolistic, with three dominant firms. At the farm level, the definition and enforcement of regulations relating to access to pasture and transitioning livestock have been the subject of controversy and slow to change to meet the needs of the sector. This paper uses two sources of the United States Department of Agriculture (USDA) data (Agricultural Resource Management Survey and Organic Survey) and other evidence to trace changes in the discourse about organic dairy, the market, processing and farm sector, along with the evolution of the regulation. Concern over inconsistencies in the language and enforcement of the regulation at the farm level continued throughout the 30-year period. We find evidence of strong and continued growth of the organic dairy sector at the farm level, among all regions of the US. The amount of pasture available per cow increased as the access to outdoor rules tightened. In 2016 many dairies failed to meet the 30% threshold for feed from grazing. Another key finding, which may underlie the internal debates, is that the profitability of large-scale organic dairies in the West substantially increased in 2016. The organic dairies in other regions did not experience this improvement, although their profitability remained similar to prior years. While there is evidence of problems with the regulation, we note that the structure of the processing sector is an important but overlooked dimension. Thus, additional research into the farmer–processor relationship is needed to improve our understanding of the dynamics of the organic dairy farm sector.

This study uses choice experiments to assess fresh produce and hay/forage grower preferred drought management strategies, the level of drought at which growers adopt specific management strategies and the level of drought at which they choose to exit farming in the arid west. Results show preferred strategies differ by drought level and across grower groups. Using logit models, we find that fresh produce growers prefer adopting a water-saving technology (cover crops, manure/mulch application, etc.) and hay/forage growers prefer switching to a more efficient irrigation system. Growers would only exit farming in extreme circumstances such as loss of all water resources. Policies aimed at assisting growers with drought adaptation should focus on preferred strategies to ensure effectiveness. Incentives to offset adoption costs are also recommended. Additionally, growers may benefit from information related to productivity changes under various drought management strategies and drought scenarios.

The introduction of cover crops as fallow replacement in the traditional cereal-based cropping system of the Northern Great Plains has the potential to decrease soil erosion, increase water infiltration, reduce weed pressure and improve soil health. However, there are concerns this might come at the cost of reduced production in the subsequent wheat crop due to soil water use by the cover crops. To determine this risk, a phased 2-year rotation of 15 different cover crop mixtures and winter wheat/spring wheat was established at the Northern Agricultural Research Center near Havre, MT from 2012 to 2020, or four rotation cycles. Controls included fallow–wheat and barley–wheat sequences. Cover crops and barley were terminated early July by haying, grazing or herbicide application. Yields were significantly decreased in wheat following cover crops in 3 out of 8 years, up to maximum of 1.4 t ha−1 (or 60%) for winter wheat following cool-season cover crop mixtures. However, cover crops also unexpectedly increased following wheat yields in 2018, possibly due in part to residual fertilizer. Within cool-, mid- and warm-season cover crop groups, individual mixtures did not show significant differences impact on following grain yields. Similarly, cover crop termination methods had no impact on spring or winter wheat grain yields in any of the 8 years considered. Wheat grain protein concentration was not affected by cover crop mixtures or termination treatments but was decreased in winter wheat following barley. Differences in soil water content across cover crop groups were only evident at the beginning of the third cycle in one field, but important reductions were observed below 15 cm in the last rotation cycle. In-season rainfall explained 43 and 13% of the variability in winter and spring wheat yields, respectively, compared to 2 and 1% for the previous year cover crop biomass. Further economic analyses are required to determine if the integration of livestock is necessary to mitigate the risks associated with the introduction of cover crops in replacement of fallow in the Northern Great Plains.

Late blight, caused by the oomycete Phytophthora infestans, poses a significant challenge to organic tomato and potato production systems across the globe. To enhance education and outreach programming pertaining to tomato organic late blight management in Wisconsin, we sought to identify grower strategies and needs through an online survey conducted during spring 2018. Our findings demonstrated that organic growers emphasized crop diversity, crop rotation and soil health in their late blight management decisions. Grower concerns about biopesticides were identified and suggest that the use of input-based products within integrated management programs could be enhanced by further research on effectiveness and modes of actions. Additionally, stronger emphasis on oomycete pathogen biology and the significance of late blight as a community disease were identified as important areas of emphasis in the development of organic disease management education programming and resources that promote more effective cultural and chemical disease management strategies that adhere to the regulation and principles underlying the USDA National Organic Program. The integration of a live polling questionnaire conducted in winter 2019 allowed us to corroborate findings from the online survey and underscored the importance of two-way learning to enhance outreach efforts between Extension and organic growers in Wisconsin and the surrounding upper Midwestern states.