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Winter cereal rye (Secale cereale L.) (WCR) is often double cropped with maize for silage (Zea mays L.) to increase farm forage supply and profit. Spring nitrogen (N) fertilization to WCR could influence its production and quality at different harvesting times. Therefore, two on‐farm trials were conducted in the 2019–2020 and 2020–2021 growing seasons to evaluate the effect of harvesting time (late‐March to end‐of‐April considering the growth stage) and spring N fertilization (0, 23, 47, and 71 kg N ha−1) on WCR morphology, forage yield, nutrient removal, quality, and farm profit. Only two N treatments (0 and 47 kg N ha−1) were evaluated for each harvesting time in trial 1. A quadratic model best explained an increase in WCR dry matter (DM) yield in response to growing degree days (GDD) accumulation (R2 = 0.81). An increase in GDD linearly decreased WCR relative forage quality (RFQ). Benchmarking RFQ at 150 for dairy milk production indicates WCR should be harvested at a GDD of 543, at which WCR plant height was 31.8 cm and DM yield was 0.77 Mg ha−1. This resulted in loss of profit in both study years compared to later harvesting dates at higher GDDs. Benchmarking RFQ at 125 for heifer production indicated that harvest should occur at a GDD of 668, at which the WCR was 71 cm tall, and its DM yield was 2.25 Mg ha−1. Nitrogen balances were negative at the N0 treatment (0 kg N ha−1), indicating a need for some N to maximize WCR yield. We found that a rate between 21 and 47 kg N ha−1 maximizes yields reflecting slightly positive balances, in which the highest profits occur. Our results suggest that the harvesting time can be predicted by GDD and should be adjusted for RFQ. We conclude that less than 47 kg N ha−1 N fertilizer is required for WCR production in soils with manure history and high soil organic matter (>30 g kg−1). [ABSTRACT FROM AUTHOR]

The irrigated cropping systems in South Europe could benefit from soybean [Glycine max (L.) Merr.] introduction in their maize (Zea mays L.)‐based crop rotations. However, sustainable weed management strategies are needed for soybean growers under Mediterranean irrigated conditions. This work aimed to assess the weed control efficacy, and the soybean performance, of alternative management practices for single‐ and double‐cropped soybean. Two field experiments were carried out in northeast Spain in the period 2019–2021. Row width narrowing (75–37.5 cm), herbicide application (yes/no), and roller‐crimped rye [Secale cereal (L.) M.Bieb.] cover crop (yes/no) were assessed in the single cropping system experiment (SCS). In the barley‐soybean double cropping system experiment (DCS), row width narrowing and herbicide application were assessed. In the SCS, the presence of rye cover crop reduced weed biomass up to 92% compared to the controls without herbicide and cover crop in 2020. In 2021, no effect of the cover crop on weed pressure was found due to the low amount of rye biomass accumulated (11.8 and 3.4 ton DM ha−1 in 2020 and 2021, respectively). In the DCS, herbicide application attained the expected weed control. Row width narrowing to 37.5 cm did not have an impact on weed pressure nor on soybean yield in either experiment. We concluded that herbicide reduction for single‐cropped soybean under Mediterranean irrigated conditions can be achieved by roller‐crimping a rye cover crop, provided enough rye biomass is accumulated. In the DCS, our results indicated that further research is needed to find alternatives to chemical weed control. Core Ideas: Roller‐crimped rye cover crop controlled weeds in soybean when enough biomass was accumulated.Roller‐crimped rye effectively controlled most weed species, especially Datura stramonium L. and Setaria adhaerens (Forssk) Chiov.Narrowing row width from 75 to 37.5 cm did not improve weed control or soybean yield. [ABSTRACT FROM AUTHOR]

Conventional dryland cropping systems are characterised by low crop diversity and frequent fallows. This has significant impacts on soil microbes that underpin soil function. Diversifying crop rotations can potentially counter these effects; however, limited data exists on the impacts of diversified crop rotations on soil microbes in drylands. Using phylogenetic marker gene sequencing, we characterised soil microbial diversity in conventional and diversified dryland crop rotations in subtropical Australia. This included winter and summer dominant rotations. Conventional systems were cereal-dominant with a crop-fallow rotation. Diversified systems included greater crop diversity, double crops, cover crops, and a multi-year ley pasture. In summer rotations with increased crop diversity and cover crops, bacterial and fungal richness increased, and distinct communities were formed compared to fallow land. Often, these community shifts were associated with greater soil organic carbon (SOC) and nitrogen. All winter rotations had distinct fungal communities and ley pasture resulted in greater fungal diversity compared to other rotations. No effects of the winter rotations were evident on bacterial communities. Our results show that diversification of dryland crop rotations leads to significant shifts in soil microbial communities in both winter and summer cropping systems. Both summer and winter rotations incorporating cover crops and ley pasture had greater soil respiration and nitrogen, indicating increases in soil fertility. These rotations may offer an alternative to conventional crop-fallow rotations to counter ongoing declines in soil health. [ABSTRACT FROM AUTHOR]

There is interest in harnessing cropland C storage potential at a large scale to mitigate climate change and improve land productivity. While the effects of soil management practices on C storage have been studied extensively, opportunities to select for C sequestration traits in crop plants remain largely unexplored. This review describes how genetic improvement of major US crops may have altered soil C stocks historically and identifies potential opportunities for plant breeding to increase cropland C stocks. Through quantitative literature review, we find that breeding has led to an increase in aboveground residue C inputs to the soil for corn (Zea mays L.) and soybeans (Glycine max (L.) Merr) and a decrease in aboveground residue C inputs for wheat (Triticum aestivum L. and Triticum turgidum L.). Breeding has largely not altered the root:shoot ratio of these crops. Given that there is limited potential for further major improvements in harvest index, breeding for high grain yields may necessitate increasing aboveground biomass and residue production in the future. Crop root traits and residue quality may influence the stabilization of crop‐derived C in soil, but there is uncertainty regarding historical changes in these traits due to breeding, the magnitude of their effect on soil organic C stocks, and tradeoffs or synergies with breeding for high yield. Nevertheless, root traits such as suberin content, rhizodeposition, mycorrhizal association, and depth emerge as potential targets for more efficient C stabilization. There is also a large opportunity for plant breeding to enhance the performance of cover crops, double crops, perennial grains, and perennial groundcovers, which can increase annual C inputs to the soil by occupying fallow periods. Our review reveals that there are many opportunities for plant genetic improvement to fix more C in cropping systems and enhance its stabilization in the soil to meet the goals of sustainable intensification and cropland C capture. Core Ideas: Plant breeding has increased aboveground residue C inputs to the soil for corn and soybean, but not for wheat.Root:shoot ratio and mycorrhizal colonization have not substantially changed due to plant breeding.There is little evidence that breeding has altered the quality or placement of C inputs.There is opportunity for plant breeding to increase soil C by overcoming barriers to cropping system enhancement. [ABSTRACT FROM AUTHOR]

Double-cropping winter rye cover crops (CC) with soybean in the North Central US could help with the global effort to sustainably intensify agriculture. Studies addressing the management of these systems are limited. Therefore, a field study was conducted from 2017 to 2019 in Central Iowa, US to evaluate winter rye CC biomass production, aboveground N accumulation, estimated economics, estimated within-field energy balance and estimated greenhouse gas (GHG) emissions under three N application rates (0, 60, 120 kg N ha−1) and three planting methods (pre- and post-harvest broadcast and post-harvest drilling). Averaged over N rates, all planting methods resulted in >5.0 Mg ha−1 year−1 rye aboveground biomass dry matter. Averaged over the 2-year study and compared with unfertilized treatments, applying 60 kg N ha−1 produced 1.1 Mg ha−1 more aboveground biomass (6.1 vs 5.0 Mg ha−1), accumulated 30 kg ha−1 more N in aboveground biomass (88 vs 58 kg N ha−1), and led to 20 GJ ha−1 more net energy. Biomass production was not significantly higher with 120 kg N ha−1 compared with the 60 kg N ha−1 rate. Even when accounting for an estimated 0.75 Mg ha−1 of above ground rye biomass left in the field after harvesting, more N was removed than applied at the 60 kg N ha−1 rate. The minimum rye prices over the 2-year study needed for double-cropping winter rye CC to be profitable (breakeven prices) averaged $117 and $104 Mg−1 for the 0 and 60 kg N ha−1 rates, which factors in estimated soybean yield reductions in 2019 compared with local averages but not off-site transportation. GHG emissions were estimated to increase approximately threefold between the unfertilized and 60 kg N ha−1 rates without considering bioenergy offsets. While environmental tradeoffs need further study, results suggest harvesting fertilized rye CC biomass before planting soybean is a promising practice for the North Central US to maximize total crop and net energy production. [ABSTRACT FROM AUTHOR]

A sustainably intensified (SI) organic vegetable rotation, employing plant-based fertilizers, more crops, reduced tillage, and cover crops was compared to common practice (CP) where plants were fertilized with animal manure, typically one crop was grown per season, soil was plowed and often left bare over winter. Second and third-year results are presented. Nitrogen (N) input obtained within the rotation from N2 fixed by legume cover crops was higher under SI (34% potential self-sufficiency) than CP (5%). Marketable yields of cabbage, celeriac, leek, lettuce, and onion were similar, and aboveground dry matter increased by 16% under SI (8.6 Mg ha−1) compared to CP (7.5 Mg ha−1). Nitrogen use efficiency (N output/ N input) was 8–16% higher under SI compared to CP, mainly due to the full year clover. Nitrogen surface balance (N input – N output) was higher for SI compared to CP, indicating increased N leaching risk under SI. Short season and shallow-rooted crops under SI left more mineral N to 2.5 m depth in autumn than deeper-rooted crops under CP. Cover crops indicated to mitigate N leaching risk. Vegetable production can be intensified sustainably using more yielding crops, cover crops, reduced tillage, and plant-based fertilizers. [ABSTRACT FROM AUTHOR]

Across the Brazilian Cerrado, the land area under soybean-maize (double cropping) and maize-brachiaria (intercropping) systems has been expanding. In this study, we evaluated the efficiency of P fertilization and the response of residual P compartments to i) soybean monoculture in conventional (CT) or no-tillage (NT), ii) soybean in rotation systems including the maize+brachiaria consortium; and iii) soybean in succession systems including soybean-maize double cropping. These factors were combined into eight treatments in an experiment conducted at Itiquira, Mato Grosso, Brazil. Our study was laid out following a completely randomized block design with four replicates. We determined the apparent efficiency of P fertilization using the balance method for 12 years, after which residual P was evaluated in soil samples submitted to a soil P fractionation scheme using CaCl 2 , Mehlich-3, NaOH (inorganic-Pi and organic-Po) and HCl. P occluded was estimated as the difference between total soil P and the sum of the extractable P fractions. Our data showed apparent efficiency of P fertilization about 78.3 % under soybean-fallow (CT or NT) and about 93.0–94 % under the soybean-successions. Under the rotations, the apparent efficiency of P fertilizations was about 100–123.0 % coupled to some depletion of P-Mehlich-3 and Pi-NaOH. We found positive correlations between P-Mehlich-3 and Pi-NaOH, whereas both Po-NaOH and P-Mehlich-3 showed strong negative correlations with P occluded. Overall, the rotation systems evaluated in this research appear to benefit from the transfer of P between P-Mehlich-3 and Pi-NaOH pools, coupled to the formation of Po-NaOH limiting the accumulation of P occluded. These characteristics allow reconciling productive crop grain systems with efficient P fertilizations and recycling of P in soils with high residual P pools in tropical agroecosystems. • The efficiency of P fertilization was evaluated in a 12-year field experiment. • Soybean, maize and cover crops were managed in successions and rotations. • Fertilization efficiency was estimated using the balance method. • In the rotation treatments the efficiency of P fertilization was higher than 100 %. [ABSTRACT FROM AUTHOR]

Long-term sustainability of intensive cropping systems in tropical soils depends on strategies to reconcile grain output, cover crops to maximize biomass yield for soil mulching, and maintaining soil organic carbon (SOC). In this study, we evaluated spatiotemporal constraints underpinning the diversification from soybean (Glycine max (L.) Merr.) monoculture under conventional tillage (CT) or no-tillage (NT) and soybean in succession with maize (Zea mays L.) double cropping (NTS3) to the use of millet (Pennisetum glaucum L., NTS1) and brachiaria (Brachiaria ruziziensis (R.Germ. & Evrard) Crins, NTS2) in successions or millet, crotalaria (Crotalaria spectabilis Roth.), and maize+brachiaria in rotations in a 12-year field experiment in an Oxisol. We quantified total grain output, total biomass production, and SOC contents and stocks (0–40 cm depth). Over 12 years, cumulative grain output under the double cropping (NTS3) was 135.0 Mg ha−1, with soybean-maize proportions of 35–65 %. Thus, the successions NTS1 and NTS2 would reduce maize grain output relative to NTS3 (7.3 Mg ha−1 year−1). Under the rotations, reduction in soybean and maize grain output relative to NTS3 was about 1.4 and 4.1 Mg ha−1 year−1, respectively. Biomass production under NTS3 was 12.0 Mg ha−1 year−1 but reached 15.7 Mg ha−1 year−1 under the rotation including summer soybean (1st and 2nd years) and off-season crotalaria (1st year) or maize+brachiria (2nd year), and only brachiaria (3rd year). Under this rotation, changes in SOC stocks were +2.0 Mg ha−1 year−1 for the 0–40 cm depth layer, whereas under NTS3 it was +1.4 Mg ha−1 year−1, relative to the native Cerrrado. For soybean monoculture under CT or NT changes in SOC were about −0.5 Mg ha−1 year−1 relative to the native Cerrado. Overall, despite the reduced total grain output, the rotation system proposed may be critical to reconcile sustainable food security, soil protection by mulching and SOC maintenance in agricultural Cerrado soils. • No-tillage managements increases grain productivity. • Diversifying cover crops favors biomass production for soil mulching. • Relative to double cropping, successions or rotations may reduce grain output. • Sustainable intensification on tropical agriculture is crucial for food security. [ABSTRACT FROM AUTHOR]

Mixed cropping, including intercropping, is the oldest form of systemized agricultural production and involves the growing of two or more species or cultivars of the same species simultaneously in the same field. However, mixed cropping has been little by little replaced by sole crop systems, especially in developed countries. Some of the advantages of mixed cropping are, for example, resource use efficiency and yield stability, but there are also several challenges, such as weed management and competition. The boreal-nemoral region lies within the region 55 to 70°N. In this area, for example in Finland, the length of the thermal growing season varies from >105 to over 185 days. Typically, variation between locations and years is marked. However, during the year, there can be a wide range of temperature extremes between −70 and +30°C. The majority of cropping systems in this region are usually monocultures, except for forage grass mixtures. The possibility of having several crops in a mixture is very challenging in the region due to the short growing season and extreme cold temperatures, meaning that crop earliness and overwintering capacity are a considerable restriction for year-round mixed cropping. A further restriction is the quality requirements set by the industry. Our review will explore a range of mixed cropping possibilities for the boreal-nemoral region, including different possible combinations of spring, winter, perennial, biennial, catch, and cover crops. The reviewed mixed cropping systems could considerably improve the sustainability and efficiency of crop production.

Double cropping forage cereal rye (Secale cereale L.) with corn (Zea mays L.) and injecting liquid dairy cow (Bos taurus L.) manure in the fall may increase manure nutrient utilization and total forage production. Although potentially economically and environmentally beneficial, these practices have not been widely adopted by Northeastern U.S. farmers. This 2‐yr full‐factorial experiment conducted in Pennsylvania quantified the effects of (a) rye management (RyeM; early terminated cover crop, CC vs. double crop harvested approximately 1 wk later, DC) and (b) manure application method (ManM; unincorporated broadcasted manure, BM vs. shallow disk injected manure, IM) on rye biomass, rye apparent manure nitrogen and phosphorus recovery (ANR and APR, respectively), subsequent corn silage yield, and total forage production (DC + summer corn silage) and the effect of ManM on DC forage nutritive value. Double cropping increased rye biomass 143%, ANR 119%, APR 126%, and total forage production 29–44% compared to CC. While IM did not increase net returns on rye silage production compared to BM, IM improved rye forage nutritive value by increasing ANR by 84%, rye crude protein by 29%, net energy of lactation by 10%, and reduced neutral detergent fiber (NDF) by 10%. Injecting manure also increased summer corn yield 21% and total forage 13% when rye was harvested as DC compared to DC with BM. Farmers adopting DC can increase total forage production and nutrient recovery and, when combined with IM, forage production and rye quality can potentially be improved. [ABSTRACT FROM AUTHOR]

Winter rye (Secale cereale L.) is a popular cover crop in North Central United States for preventing soil erosion and nutrient losses, among other agronomic and ecosystem benefits. Winter rye can also be a high-quality spring forage option when double-cropped with corn silage (Zea mays L.), thus adding diversity to monocrop rotations. However, these sustainability-promoting benefits have potential trade-offs including soil nutrient immobilization and decreased corn yields. We hypothesized that winter rye would promote sustainable intensification of corn silage, as substantiated by decreased nitrogen budget and soil nitrate without yield loss. We also predicted that winter rye double-cropped and harvested as a forage would maintain total production (corn silage + rye harvest) compared to corn silage alone. This five-season study is representative of continuous corn silage systems in North Central United States, and Wisconsin specifically, distinguished by fall liquid dairy manure applications. Corn was planted after rye termination or harvest, and varying rates of nitrogen were applied to corn. As predicted, rye cover reduced preplant soil nitrate without affecting corn silage yield. Rye harvested as a forage crop reduced preplant and in-season soil nitrate, and total production equaled or exceeded corn silage yields without rye, despite a 13% decrease in corn silage yield. The 5-year nitrogen balance demonstrated almost 40% reduction in excess nitrogen in the rye forage system. This novel study demonstrated no cumulative or single-year agronomic limitations to winter rye implementation in manured, corn silage systems characteristic of North Central United States over a range of seasonal weather conditions. Furthermore, the dual use of rye as a cover crop conservation practice or harvested as a forage double-crop makes it agronomically advantageous and demonstrate potential for sustainable intensification in this system. This research is the first to show that sustainable intensification through double cropping dairy-based systems can increase high-quality biomass production while reducing nitrogen losses to the environment. [ABSTRACT FROM AUTHOR]

Frequent soil cultivation in intensive vegetable production is detrimental to soil quality. Combining several sustainable management techniques, such as increasing organic matter input and plant diversity, and reducing soil cultivation, could benefit biological soil quality. We designed a crop rotation with a system approach, combining plant-based fertilisers, cover crops and reduced tillage, while growing more crops (sustainable intensification, SI). We compared this approach to common practice (CP), where animal manure fertilisers, no cover crops and ploughing were employed in a standard organic crop rotation on sandy loam in Denmark. Treatments were initiated in 2017, and two sets of contrasts, each comparing across cropping systems and specific crop rotations, were investigated in the second and third year of implementation: lettuce-leek double-cropping (SI) vs. leek sole-cropping (CP), and onion-lettuce intercropping (SI) vs. lettuce-lettuce double-cropping (CP). Soil microbial activity was assessed by β-glucosidase and dehydrogenase activity and potential N mineralisation over 28-days incubation. Root growth was investigated using minirhizotrons. The risk of N leaching was estimated from soil mineral N content at 0–2.5 m depth in autumn. β-glucosidase and dehydrogenase activity increased by 27–107% under SI compared to CP in the third year after implementation. SI improved potential N mineralisation by 12–52 kg N ha−1 before and after spring fertilisation both years. Increased soil fertility under SI contributed to 1.3 to 2.3 times higher plant N uptake (except for lettuce/onion first year), and 1 to 2.7 times higher marketable yields, but only minimally affected root depth. Despite higher N fertilisation, risk of N leaching did not rise under SI. The beneficial effects of SI were attributed to the combination of higher N fertilisation (53–144 kg N ha−1 more) as organic matter addition (2–3 Mg carbon ha−1 more), growing cover crops, and reducing soil tillage. Combining these techniques is promising for improving soil microbial activity in a sustainable way for highly intensive organic vegetable production. • Plant-based fertilisers and reduced tillage enable sustainable intensification. • A sustainably intensified cropping system improves soil microbial activity. • Soil enzyme activity responds to management changes after 3 years. • Higher fertilisation did not increase risk of N leaching in sustainable intensification. [ABSTRACT FROM AUTHOR]

Forage double cropping can be a beneficial practice for dairy farmers in the northeastern United States, providing an additional, harvestable crop plus many environmental benefits. Triticale (x Triticosecale Wittm.), winter wheat (Triticum aestivum L.), and cereal rye (Secale cereale L.) are forage double crop options in New York that require nitrogen (N) management. From 2013 to 2016, 62 N-rate trials were conducted across New York with five N rates (0, 34, 67, 101, and 135 kg N ha-1) applied in four replications at spring dormancy break. Forage was harvested at flag-leaf stage in May (Feekes stage 9). Soil samples were taken prior to N-application at dormancy break. Management practices and field characteristics were evaluated as predictors (using classification tree analyses) for yield and the most economic rate of N (MERN) at dormancy break, determined using a quadratic plateau model. Approximately one-third of the sites did not respond in yield to spring N application, averaging 4.3 Mg DM ha-1. Of the remaining sites, ~80% had MERNs ranging from 47 to 112 kg N ha-1, averaging 77 kg N ha-1, with yields at the MERN from 2.2 to 6.9 Mg DM ha-1, averaging 4.2 Mg DM ha-1. Yield could not accurately be predicted statistically. However, low-yielding sites lacked fall manure application and well-drained soils. We conclude that forage winter cereal fields with well-drained soils, recent manure applications, and timely planting may not need additional N at dormancy break, while others require approximately 19 kg N ha-1 per Mg DM ha-1.

The influence of poultry litter (PL) and cover crops have under no-till cropping systems in Mississippi upland soils on cotton (Gossypium hirsutum L.) yield and subsequent soil health are largely unknown. A 4-yr field study was conducted to determine the effect of winter wheat (Triticum aestivum L.) cover crop and PL on cotton lint yield in narrow (0.75 m) and conventional (1.01 m) row spacings. The experimental design was split-split plot with three replications. The cover crop treatment was assigned to the main plots. Within the cover crop treatment, a narrow row spacing compared to conventional row spacing as subplots. Fertilization treatments included unfertilized control, inorganic N fertilizer (112 kg N ha-1) and PL (6.7 Mg ha-1). Lint yield was significantly greater with PL than inorganic fertilizer each year. Lint yield in a dry season was significantly greater with cover crop treatment. However, following the cessation of PL in 2017, lint yield increased by 12% in the absence of cover crop residue. As compared to unfertilized control, applying PL in the presence of cover crop residue enhanced soil C by 22% and water aggregate stability by 7.4% and reduced soil penetration resistance and bulk density by 9 and 3.5%, respectively. Applying PL for 3 years increased soil levels of both gram-negative bacteria, 16S rRNA, and ureC, while planting cover crop doubled heterotrophic plate count bacteria. Integration of PL and cover crop residue in a no-till cotton increased lint yield and improved soil quality indicators. [ABSTRACT FROM AUTHOR]

Cropping systems based on a single crop per year, such as soybean monoculture, result in an inefficient use of available resources and low productivity, and are usually related with a negative environmental impact. The intensification of soybean-based cropping sequences can increase resource productivity, enhancing the sustainability of the production systems. This study aimed to analyse the long-term effect of intensification practices in soybean-based sequences on: i) water and radiation productivity, and ii) soybean yield, in four temperate and fully humid environments with contrasting soil texture. The study was carried out in four long-term experiments where three cropping sequences were evaluated: soybean monoculture, cover crop (CC) / soybean, and a three-year crop rotation including wheat (Triticum aestivum L.), maize, CC, and soybean. Oat (Avena sativa L.), triticale (x Triticosecale Wittmack), wheat, or rye (Secale cereale L.), were used as CC. Four 3-yr rotation cycles were evaluated between 2007 and 2018. Intensification of cropping sequences increased soybean yield (17%) in one out of four sites, and did not significantly change in the other three sites. Soybean yield varied among cycles at all sites and was positively associated with rainfall during the growing season (r = 0.81). Intensified sequences increased over 40% both water and radiation productivity as compared with soybean monoculture. Despite the different edaphoclimatic characteristics of the evaluated locations, the magnitude of the improvement in the productivity of the resources resulting from the intensification of cropping sequences was similar at all sites. Therefore, in temperate and fully humid environments with contrasting soil texture, the intensification of soybean-based sequences with grasses, CC, and double crops is a feasible alternative to increase the productivity of resources without compromising soybean yield, hence, it should be taken into account by government organizations when developing policies. • We studied intensification practices long-term effects on water and radiation productivity and soybean yield. • Intensified sequences increased > 40% water and radiation productivity as compared with soybean monoculture. • Intensified cropping improved productivity equally at different sites despite varying edaphoclimatic traits. • Soybean yield was either increased (n = 1, +17%) or unaffected (n = 3) by the intensification of cropping sequences. [ABSTRACT FROM AUTHOR]

Conservation practices such as green manures and no-tillage can reduce soil erosion, enhance soil biological activity, increase water storage in soils, and provide nitrogen (N) in support of winter wheat (Triticum aestivum L.). However, green manures utilize soil water during the summer months, and such water depletion may negatively impact production by wheat in ecoregions with limited water resources. This 5-year study quantified the impacts of tillage systems and green manures on water storage efficiency (WSE) during summer, water use efficiency (WUE), and grain yield of winter wheat. The study was conducted during 2011–2016 in the United States (US) Southern Great Plains (SGP). Three legumes as green manures (cowpea, pigeon pea, and soybean) were compared with summer fallow and three levels of applied inorganic N (0, 45 and 90 kg N ha-1) at wheat planting, under conventional and no-till cultivation. Summer WSE was significantly (P < 0.05) reduced in response to green manures; summer fallow was also inefficient in storing soil water. Grain yield and WUE of wheat were reduced in response to green manures compared to summer fallow during dry years but there were no differences during wet or normal rainfall years. No till significantly increased WSE under all treatments, and reduced evapotranspiration during a subset (either summer or wheat growing season) of years but did not affect amounts of soil water. Our results demonstrate replacing summer fallow in continuous systems of winter wheat with green manures have limited effects on improving water availability or efficiencies in water use by wheat. More-effective approaches for using green manures to support winter wheat in the SGP include opportunity cropping during years with adequate moisture to support double-cropping or utilizing more water-efficient legumes or cropping systems. • WSE, WUE, and wheat yield responses to different crop rotations were assessed. • Summer fallow was inefficient in storing precipitation water. • Replacing the summer fallow with cover crops did not increase WSE. • Planting cover crops helped to increase system WUE during normal or wet years. • Winter wheat yield response to cover crop biomass production was negatively linear. [ABSTRACT FROM AUTHOR]

The design of sustainable, high-yielding continuous cropping systems requires to maintain, or even restore, critical ecosystem properties, such as soil functioning. In the rolling Pampa (Argentina), total soil organic carbon decreased by 15–40% due to continuous agriculture. Therefore, soils are far from their potential carbon saturation. The most promising strategies to increase yield and restore carbon rely on the sustainable intensification of the current cropping systems based on no-tillage practices. Such strategies also involve increasing resource use through cover crops, increasing cropping intensity, and performing accurate and flexible fertilization and crop protection schemes. This study evaluated the effects of different cropping systems on soil organic carbon stocks in the uppermost 20 cm of the soil profile. We performed a 5-year experiment combining five cropping systems with different cash crop sequence (soybean mono-cropping and two different rotations) and agronomic technology (genotypes, fertilization, and crop protection), which in turn were evaluated under both fallow and cover cropping. Five years after the beginning of the experiment, all systems had a net positive balance of soil carbon accumulation, which averaged 2.25 t C.ha-1.yr-1. On average, 41% of plant carbon inputs remained within the first 20 cm of the soil profile. Cover crops increased plant carbon inputs, with larger effects as the cash crops occupied a shorter period in the field. Therefore, compared to fallow, cover crop doubled carbon input in soybean mono-cropping, had intermediate increments in the maize-soybean sequence, and had the lowest increments in the wheat/soybean-maize-soybean sequence. Under fallow, both rotations outperformed the plant carbon inputs of soybean mono-cropping. Management intensification, only evaluated for rotations, increased plant carbon inputs and soil carbon accumulation in a synergistic interaction with cover crop. Our results indicate that increasing carbon inputs through crop rotation, cover cropping and better agronomic technology is an opportunity to revert the long trend of soil carbon deficit of these agricultural lands. • Approximately 41% of plant carbon inputs remained in soil. • Intensified management and cover cropping acted synergically. • Crop rotations with more frequency of maize accumulated more soil carbon. • Cover cropping doubled annual carbon inputs of soybean mono-cropping. [ABSTRACT FROM AUTHOR]

Agricultural intensification, besides increasing land productivity, also affects weed communities. We studied weed shifts in cropping sequences differing in the identity and number of crops grown. We also evaluated whether dissimilar weed communities in different cropping systems converge towards more similar communities, when the same sequence is cropped during 2 years. In three locations in the Rolling Pampa, Argentina, field experiments were conducted including five cropping systems in the first year (winter cereal/soyabean, field pea/soyabean, and field pea/maize double crops, and maize and soyabean as single crops), while the same sequence was grown in the following 2 years (wheat/soyabean double crop and maize). Changes in weed community composition and structure were analysed through multivariate analyses and frequency-species ranking plots. Weed communities differed first among sites, while weed shifts within each site were mainly associated with growing season and crop type. Differences among crop sequences were higher in the first year, mostly related to specific crop grown, rather than to the number of crops in the sequences. Differences were reduced when the same sequence was grown during two consecutive seasons. Frequency of highly common weeds was negatively associated with the number of days with high crop cover. Our findings contribute to understand weed shifts in consecutive growing seasons, which may help readapting crop sequences to reduce the occurrence of abundant weed species. [ABSTRACT FROM AUTHOR]

Cover crops (CC) have the potential to increase water storage by reducing runoff, increasing infiltration, and decreasing evaporation. Interseeding CC into a summer cash crop can increase CC biomass production essential for maximizing beneficial services. Effects of interseeded CC on soil water content during the following cash crop has not been fully evaluated in the Mid-Atlantic USA. Soil water content was measured during the corn (Zea mays L.) phase of four no-till rotations at the USDA Beltsville Agricultural Research Center, Beltsville, MD from 2017 through 2020. All systems included corn-soybean (Glycine max L.)-wheat (Triticum aestivum L.) rotations, and Systems 3, 4 and 5 added double crop soybean (DCS) after wheat. In System 5, a mix of rye (Secale cereale L.)-hairy vetch (Vicia villosa Roth)-crimson clover (Trifolium incarnatum L.) was interseeded into DCS. In System 6, red clover (rc , Trifolium pratense L.) was interseeded into wheat and rye was planted into rc after wheat harvest. In 2017 and 2018, season average soil water storage was 20 mm greater in systems with CC before corn compared to no CC before corn (NC). A similar, but non-significant, trend was present in 2019 and 2020 (11 mm). Estimated evapotranspiration was lower for CC compared to NC systems in 2018, while greater estimated infiltration was observed for CC compared to NC systems in 2019. Four-year average corn yields were greater for CC compared to NC systems (12.1 vs 10.6 Mg ha−1). Similarly, average corn water use efficiency (WUE) was greater in CC compared to NC systems (5.55 vs 4.70 kg m−3). The returns from increased yield more than offset the cost of CC establishment. The combination of greater yields and WUE demonstrate the benefits of interseeded CC in humid regions of the US. • Cover crops increase soil water storage 10–20 mm in sandy soils. • Trends indicate lower cumulative evapotranspiration with cover crop residues. • Cover crops increase fraction of precipitation captured as infiltration by 23%. • Cover crops increase corn water use efficiency by nearly 1 kg m−3 and yields by 14%. [ABSTRACT FROM AUTHOR]

Crop rotations with high plant diversity and biomass input have been recognized worldwide as a crucial practice for increasing the sustainability of grain production systems, particularly in regions under no-tillage (NT) management. Nonetheless, low-diversity grain production systems based on double cropping (two crops in the same agricultural year) repeated over time, including soybean followed by maize (known in Brazil as "second crop maize") or wheat, remain prevalent in Brazil. The continuous use of these systems can impair soil yield capacity, farmers' profits, and environmental sustainability. Therefore, this study aimed to verify the grain yield and profitability of different production systems with different levels of plant diversity. This study was based on results obtained during the 2009–2017 cropping seasons through a long-term field trial conducted under NT since 1985 in southern Brazil. The trial covered two 4-year agricultural cycles with two crops per year, resulting in eight crops per cycle and 16 crops over the entire period. The experiment followed a randomized complete block design, with five treatments and four replicates. The treatments involved three diversified crop rotations, comprising different cover crops and two double-crop systems (wheat-soybean and maize-soybean). For a given agricultural year, wheat and cover crops (white oats, black oats, and forage radish) were grown from May to September, and the second crop maize was grown from March to August. Soybean and first crop maize were grown during the summer from October to February. The grain yield, gross revenue, production cost, and cumulative profit were analyzed for each production system. Gross revenue and profit were primarily estimated based on the actual annual average commodity prices received by farmers, and two additional price scenarios (pessimistic and optimistic) were proposed considering the average prices from 2010 to 2017. Regardless of the cropping season, first crop maize and wheat grain yields were higher in diversified crop rotations. The production system only affected the second crop maize yield in 2010/2011, with a higher value obtained in a diversified crop rotation system. The soybean yield in diversified crop rotations was higher than that in double-crop systems. Considering each cash crop separately, soybean produced the highest average profit (US$ 472.50 ha−1), followed by the first crop maize (US$ 245.31 ha−1) and wheat (US$ 77.71 ha−1), whereas the second crop maize led to economic losses (−US$ 121.73 ha−1). All diversified crop rotations produced a higher 8-year cumulative profit and gross margin than the maize–soybean in double-crop system. The relative economic performance of production systems remained unchanged under alternative price scenarios (pessimistic and optimistic) compared with that under the observed (actual) price scenario. However, the cumulative profit of maize and soybean in double-crop system was the most negatively impacted in the pessimistic scenario (−45.9%), indicating greater economic risk. Overall, lack of direct revenues from cover crops were compensated by increased grain yield in the spring-summer season and profitability of diversified crop rotation systems. Therefore, diversified crop rotation systems are economically competitive with double crop systems, rendering them feasible management options for conserving natural resources and increasing crop resilience to adverse climatic conditions. • Diversified crop rotation improves grain yield. • Diversified crop rotation allows sustainable intensification of agricultural systems. • Diversified crop rotation increases soybean productivity. • Diversified crop rotation increases productivity and profitability. • Diversified crop rotation can help farmers boost production and grow profits. [ABSTRACT FROM AUTHOR]

The impacts of crop diversity on ecosystem functioning can vary across environmental conditions and land use histories. We conducted a two-year experiment to assess the effects of two diversification practices—vetch-oat cover cropping and cucumber-snow pea intercropping—on nitrogen (N) cycling and productivity across a farm management gradient. The field experiment spanned 14 farms in southern Brazil with different long-term management histories, ranging from conventional tobacco to agroecological mixed crop-livestock systems. Along this gradient, farm soils with longer histories of agroecological management had higher soil organic carbon, potentially mineralizable carbon, and extractable phosphorus, captured by a principal component reflecting "biological soil fertility." We found that benefits of diversification practices for soil N cycling and productivity were ecologically relevant across the farm gradient within the two-year span of our experiment, with the greatest overall performance on agroecological farms. First, vetch-oat cover crops doubled mean N inputs to soil compared to fallows across all farms. Following cover crop incorporation, N mineralization was twice as high on agroecological farms as on transitioning or conventional farms. At vegetable planting, use of cover crop mixtures explained 67% of the variation in soil N availability, after accounting for the effects of background fertility. Finally, vegetable intercrops had higher productivity than monocrops across farms and years (mean LER=1.19), with stronger overyielding in the second year (mean LER=1.27). On a subset of farms, low soil pH constrained the performance of both diversification practices, reducing vetch N 2 fixation and vegetable intercrop yield (Land Equivalent Ratio, LER). While prior research has emphasized facilitation between diversified crops in lower fertility soils, our results suggest that diversification's advantages for nutrient cycling and productivity are robust to varied soil conditions and accrue over the course of transitions to agroecological management. • Functionally diverse crop mixtures enhance nutrient cycling in agroecosystems. • Agroecological management practices build soil fertility on farms. • Cover crops supplied more nitrogen on high fertility, agroecological soils. • Vegetable intercrops overyielded across soil and management gradients. • Acidic soils limited interspecific facilitation by constraining legume nitrogen fixation. [ABSTRACT FROM AUTHOR]

Energy crops grown on marginal lands offer an alternative supply of renewable resources while avoiding competition with food crops and supporting feed crops. To sustainably grow energy crops, the economic and environmental impacts of various crop management practices such as the adoption of cover crops, fertilization rates, harvesting methods and its end use applications for animal feed or biofuels should be investigated. In this study, we investigated the life cycle analysis (LCA) and economic evaluation of growing two energy crops (energy cane, and napier grass) on the marginal lands with three fertilizer treatments (0, 100, and 200 kg N ha⁻¹), and with a cover crop (clover, Trifolium incarnatum L) in the southeastern United States (US). Energy crop was harvested once a year in the late fall for biofuel applications, while the Napier grass was harvested twice a year: first harvested early in spring for animal feed and later harvested in the fall for biofuel application. Experimental field data such as biomass yield, crop management practices, farm inputs, and carbon stored in the soil, were determined to assess the global warming potential and the delivered cost of each energy crop. Napier grass had lower global warming (GW) impacts and biomass delivery costs, 34–153 kg CO₂ eq. per oven-dry metric ton (ODMT) and $51–$57 perODMT, respectively than that of energy cane. However, both the energy crops provided carbon sequestrations (−17 and −232 kg CO₂ eq. ODMT⁻¹) and thus net GW impact varied between 51 and (−14) kg CO₂ eq. ODMT⁻¹ based on the treatments. When the napier grass was harvested for both biofuel and fodder applications, the overall GW impacts and the delivered costs were reduced. Therefore, energy crops can be grown in marginal lands for increased carbon sequestration while reducing the GW impacts of energy crops for biofuel production. The integrated environmental and economic analyzes further demonstrated that the energy crop delivered costs and GW impacts could be further reduced, if the energy crops can be utilized for both biofuel and feed applications. • Estimated cost and environmental impacts of producing energy crop on marginal land. • Crop management practices, including cover crop and double harvest, were evaluated. • Global warming (GW) impacts and cost of napier grass were lower than energy cane. • Among all, biomass production with cover crop had the lowest GW impacts and cost. • In napier grass, co-production of biomass and fodder reduced GW impacts and costs. [ABSTRACT FROM AUTHOR]

Seasonal fallows – periods with no living plant cover – are frequently implemented in dryland cropping systems to allow recharge of soil moisture for the subsequent cash crop. Over time, repeated fallow periods deplete soil organic matter, a foundation of soil health that affects the long-term functional capacity of soils. Reducing fallow periods by growing cover crops (non-harvested crops terminated prior to reproductive development), double cropping (increasing the frequency of harvested crops), or rotating to ley pasture for several years, were investigated for their potential to improve or maintain soil functional attributes. These 'reduced fallow' systems were compared against a conventional cereal-based production system with seasonal fallows as well as against a permanent fallow. Soil in the reduced fallow systems had higher concentrations of total nitrogen and mineral-associated nitrogen compared with the conventional system and permanent fallow. Reduced fallow systems also had higher concentrations of total organic carbon and mineral-associated carbon than the permanent fallow, but not the conventional system. These changes were associated with greater soil microbial respiration and improved surface soil moisture storage at cash crop planting. The conventional, cover crop and ley pasture systems had similar soil structure with greater abundance of mega-aggregates. In contrast, the double crop system had greater abundance of micro- and macro-aggregates as did the ley pasture systems that were subject to tillage after three years in preparation for a return to cropping. The ley pasture also had substantially greater numbers of root-lesion nematodes (Pratylenchus thornei), surpassing the 2000 nematodes kg-1 threshold for economic damage. The results demonstrate that different methods for reducing fallow periods can generate a range of outcomes that are not uniformly desirable in terms of soil functional attributes. Across the indicators assessed, the cover crop system generated the widest range of improvements in soil fertility and function compared with the conventional system. This suggests cover cropping may be a valuable tool for promoting soil health in subtropical dryland farming systems. • Reduced fallow systems increased SOM, including mineral-associated C and N. • Also increased microbial respiration and topsoil moisture at cash crop planting. • Conventional, cover crop, and ley systems had greatest abundance of mega-aggregates. • Ley pasture had economically damaging numbers of root-lesion nematodes. • Cover cropping may help promote soil health in subtropical dryland farming systems. [ABSTRACT FROM AUTHOR]

The fall armyworm (FAW), Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), is a widespread pest species of various cultivated plants. The pest status of FAW in cotton in the Cerrado region of Brazil has increased with the recent changes in cotton crop systems, such as double cropping and the use of cover or winter crops with non-tillage cropping systems. In this study we investigated the performance of FAW on three major crops cultivated in the Cerrado - soybean, corn, and cotton - and millet which has been integrated into the landscape as a cover crop. Further, the damage to various reproductive structures of cotton plants by FAW larvae was determined. Both studies were conducted under field conditions. Survival of FAW larvae caged on millet plants was higher than on other hosts. The FAW reared on millet also exhibited a net reproductive rate similar to that observed on corn, which was considered the best host for FAW, and the highest intrinsic rate of increase and lowest mean generation time compared to all other hosts. In cotton, the low availability of bolls during the plant's blooming stage resulted in higher square feeding, whereas infestation during the plant's boll stage resulted in higher loss of bolls and lower attack on squares. The number of adults produced in a generation was higher when plants were infested in the boll stage. The results indicated that FAW is a threat to cotton when bolls are available and can cause significant loss of reproductive structures. In addition, based on the FAW performance feeding on millet, this cover crop can be among the reasons of FAW increasing pest status in subsequent crops. [ABSTRACT FROM AUTHOR]

This study investigated smallholder farmers' adoption preferences for cropping patterns of cover crops, duration of adoption, and supplementing technical support to reduce agrochemicals regarding sustainable farm management (SFM). A discrete choice experiment was conducted in the Hexi Corridor (D1) and the west Loess Plateau (D2) in northwest China. The results show that farmers in D1 preferred intercropping and rotating cover crops to the current single cropping system, while farmers in D2 prioritized intercropping over rotation and least preferred planting cover crops in marginal land in the double-cropping system. Farmers in both sites preferred 1 or 3 years of adoption over 5 years. Additionally, farmers in D2 preferred technical assistance to reduce the high proportion of agrochemicals. The results indicate that younger farmers with higher annual household incomes were most likely to opt out in D1. In D2, more agricultural labor inputs and raising livestock had positive effects on the adoption of the package. Moreover, farmers who cultivated cash crops were more reluctant to move away from the current cropping system. This study highlights the uses of cover crop intercropping and rotation combining with technical assistance in different agriculturally intensive cropping systems that may be useful in guiding site-specific policy. • Adoption preferences of SFM packages differ in the different agricultural intensive cropping systems. • The economic incentive is not only the prerequisite for accepting the practice but also essential for long-term adoption. • Intercropping cover crops with technical assistance improves the SFM adoption in the highly intensive cropping systems. • Adoption preference for cover crop rotation is higher in the single cropping system. [ABSTRACT FROM AUTHOR]