Summer Cover Crops Research Articles

A Mixture of Summer Legume and Nonlegume Cover Crops Enhances Winter Wheat Yield, Nitrogen Uptake, and Nitrogen Balance

Cover crops protecting soil erosion during the summer fallow in the monsoon weather may enhance dryland winter wheat yield and N relations. We examined the effects of four summer cover crops (soybean (Glycine max L., SB), sudangrass (Sorghum sudanense {Piper} Stapf, SG), soybean and sudangrass mixture (SS), and no cover crop (CK)) and three N fertilization rates (0, 60, and 120 kg N ha−1) on winter wheat yield, quality, and N relations from 2017–2018 to 2020–2021 in the Loess Plateau of China. Cover crop biomass and N accumulation, soil mineral N, and winter wheat yield, protein concentration, and N uptake were greater for SB and SS than other cover crops at most N fertilization rates and years. The N fertilization rate had variable effects on these parameters. Winter wheat aboveground biomass and grain N productivities were greater for CK than other cover crops at all N fertilization rates and years. Nitrogen balance was greater for SS than other cover crops at 60 and 120 kg N ha−1 in all years. The SS with 120 kg N ha−1 can enhance soil mineral N, winter wheat yield and quality, and N balance compared to CK and SG with or without N fertilization rates.

Tillage and cover crops effects on crop yield in wheat double‐cropping systems

AbstractThe United States is experiencing longer crop growing season in most states, which could afford producers the opportunity to diversify into double‐cropping (DC) and cover crop systems rather than the predominant summer and winter fallow systems. Thus, this study evaluated DC and cover crops effects on wheat (Triticum aestivum L.), cotton (Gossypium hirsutum L.), and soybean (Glycine max) yield under conventional tillage (CT) and no‐tillage (NT). Summer cover crops (SCCs) were sunn hemp (Crotolaria juncea L.) and sorghum sudangrass (Sorghum bicolor), while winter cover crops (WCCs) were Austrian winter pea (Pisum sativum) and wheat. Cropping systems were wheat‐fallow (W‐F), wheat‐cotton (W‐C), wheat‐soybean (W‐S), W‐SCC, WCC‐C, F‐C, WCC‐S, and F‐S. Tillage effect on crop yields varied across years. In 2021, wheat yield in CT of W‐C, W‐F, and W‐SCC (2831, 2689, and 2646 kg ha−1) significantly differed from NT of W‐S (1720 kg ha−1). No significant tillage effect was observed on cotton lint yield between W‐C and WCC‐C. For soybean, in 2020, the CT of W‐S and WCC‐S significantly outyielded the NT of W‐S and WCC‐S. Cropping system effect on wheat yield between W‐S and W‐SCC (1419 and 1987 kg ha−1) was significant in 2020 due to low stand counts in W‐SCC arising from the thick SCC biomass. Cotton lint yield in WCC‐C outyielded W‐C in all 3 years but was not significant. Soybean grain yield in W‐S was consistently higher than in WCC‐S, though not significant. Cotton lint and soybean grain yield in the fallow systems were the least. Overall, in a short term, crop yield in DC and cover crop systems were similar.

Multiple soil health indicators are responsive to summer cover crops on an irrigated organic farm

While cover crops (CC) are known to enhance soil health, outcomes are often subtle and confined to a shallow surface soil layer. We assessed 15 soil health indicators over three CC trials with a 15-species Blend polyculture, a Mustard biculture (white ( Sinapsis alba L.) and brown ( Brassica juncea (L.) Czern.) mustards), Buckwheat ( Fagopyrum esculentum Moench), and Faba bean ( Vicia faba L.) monocultures, and a Weedy fallow (no CC, weeds allowed to grow) on an organic farm in southern Alberta. Soil sampling times included (i) summer pretermination; (ii) fall post-termination; and (iii) spring post-termination of CC. Twelve of 15 soil health indicators showed significant effects of CC treatment for at least one sampling time. Soil organic C (SOC) ranked highest with 80% of sampling times showing significant CC effects. N-related indicators (total N (TN), nitrate-N)) were also quite sensitive, being significantly affected by CC treatment at 60% of sampling times. Three soil health indicators (acid phosphomonoesterase (AcP), wet aggregate stability, and free-living nematodes (FLN)) were consistent in their nonresponses to CC treatment at all sampling times. Comparing CC treatments with a Weedy fallow, showed that not all enhancements of soil health were explained by inclusion of a CC, with Weedy fallow as effective for some indicators. A polyculture Blend significantly enhanced soil health over a monoculture CC or Weedy fallow in 46% of instances of soil health indicator improvement. While CC led to enhancement of soil health, results were not always consistent, being contingent on specific indicators.

Soil mineral nitrogen and winter wheat nitrogen productivity influenced by summer cover crop and nitrogen fertilization

Cover crops and nitrogen (N) fertilization may affect soil mineral N, N uptake, and N productivity (grain yield per unit plant available N) in wheat (Triticum aestivum L.). We evaluated the effect of summer cover crops and N fertilization rates on soil mineral N and winter wheat grain yield, N uptake, and N productivity in the Loess Plateau of China. We measured cover crop aboveground biomass N, soil mineral N (0-20 cm), and winter wheat yield, N uptake, and N productivity for four seasons from 2017-2018 to 2020-2021. Cover crops were soybean (Glycine max L., SB), sudangrass (Sorghum sudanense [Piper] Stapf, SG], soybean and sudangrass mixture (SS), and no cover crop (CK) and N fertilization rates were 0, 60, and 120 kg N ha−1 applied to wheat. The SB increased cover crop biomass N and soil mineral N by 15 to 65%, but SS increased winter wheat yield, protein concentration, and N uptake by 25 to 55% compared to SG and CK at most N fertilization rates and years. Nitrogen fertilization rate had a variable effect on cover crop and wheat parameters. Wheat N productivity was 55 to 85% greater with CK than cover crops, but decreased with increased N fertilization rates. The N fertilizer equivalence of cover crops for wheat yield and N uptake ranged from 31 kg N ha−1 for SG to 150 kg N ha−1 for SS. Overall, SS with 60 kg N ha−1 can sustain winter wheat N uptake and N productivity compared to SG or CK with or without N fertilization.

The Potential of Three Summer Legume Cover Crops to Suppress Weeds and Provide Ecosystem Services—A Review

Recently, there has been growing interest in the use of summer cover crops that can be grown during summer fallow periods of crop rotation. This study evaluates the potential of sunn hemp (Crotalaria juncea L.), velvetbean [Mucuna pruriens (L.) DC.] and cowpea [Vigna unguiculata (L.) Walp.]. as three annual legumes summer cover crops. The main objective of this review was to conduct global research comparing these summer cover crops to investigate the benefits, challenges, and trade-offs among ecosystems services when implementing these summer cover crops. In European agriculture, there are three main windows in crop rotation when these summer legumes can be grown: Around mid-spring after winter fallow, early summer after harvest of a winter crop, and mid- to late summer after harvest of an early-season crop. All three legumes can suppress weeds while they are actively growing. After termination, their mulch can create unfavorable conditions for weed emergence. Sunn hemp and velvetbean cover crops can cause a reduction in weed biomass of more than 50%. In addition to their ability to suppress weeds, sunn hemp, velvetbean, and cowpea provide a variety of ecosystem services, such as improving soil health, quality, and fertility, controlling pests, and sequestering carbon. The review highlights their promising role in weed suppression and their contribution to sustainable agricultural practices. However, further research is needed to evaluate their performance in weed management and their environmental impact in field trials under different soil-climatic conditions, as cover cropping is an effective practice but highly context-specific.

Competition or facilitation for stored soil water by cover crops in rotation and additional effect of fertilization in a juvenile tung-based intercropping system

Intercropping or agroforestry systems are among the strategies used to prevent soil erosion or crusting and water loss by evaporation in the bare soil during early growth stage of tree crop plantations. However, the pattern of water use in intercropped, juveline orchard crop plantations is still poorly known. This study aimed to evaluate competition or facilitation for soil water stored by cover crops in rotation and the impact of additional fertilization in a juvenile tung-based intercropping system in southern Brazil during the winter and summer periods of 2012/2013 and 2013/2014 growing seasons. A split plot in randomized complete block design arrangement, with four replications, was used comprising crambe winter cover crop plus poultry manure or NPK; a mixture of oats and vetch, sunflower, and soybean in rotation; and sole tung as control. Cover crop intercropping significantly increased water content of the surface layer of the juvenile tung soil only at the beginning of the second growing season. The cover crops showed interspecific facilitation for water use by tung during the summer period, but no clear-cut trend for the winter cover crops. The additional organic manure did not enhance profile soil water storage. Any of the summer cover crops (soybean, sunflower, or peanut) could be used for soil and water conservation in juvenile tree crop plantations. Further studies are required during the winter season to establish whether the winter cover crops are competitors or facilitators for stored soil water in agroforestry systems.

Summer cover crop and temporary legume-cereal intercrop effects on soil microbial indicators, soil water and cash crop yields in a semi-arid environment

ContextFew studies have investigated summer cover crops as a replacement for bare fallow in semi-arid temperate regions, and summer cover crop impacts on soil biological function, water balances and subsequent winter crop yields in these regions remain largely unknown. ObjectiveThe 4-year field study aimed to determine the consequences of replacing a summer fallow with a summer growing cover crop on soil function, water balances and subsequent winter cash crop yields in a semi-arid region (486 mm mean annual rainfall) of the Australian southern cropping zone. MethodsA canola (Brassica napus)-wheat (Triticum aestivum L.) rotation with summer fallow was compared to the same rotation with either i) a single species (buckwheat, Fagopyrum esculentum L.) summer cover crop; ii) a four-species mixed brassica + cereal summer cover crop or iii) a cropping sequence with a temporary legume intercrop in the wheat phase of the rotation. Cover crop biomass production, soil water to a depth of 90 cm at cash crop sowing, crop yields and soil functional indices were quantified. ResultsCover crops produced 500–700 kg biomass ha−1 in the 2020 and 2021 seasons and 1000–2400 kg biomass ha−1 in 2022. The four-species mixed cover crop significantly lowered soil water (around 30 mm; P < 0.05) at the time of sowing the cash crop compared to the control and resulted in 15% reduction (P = 0.12) in canola seed yield in 2020, but no significant effect of cover crops of soil water and mineral N at sowing, or cash crop yields, were observed in subsequent seasons. In 2021 the temporary vetch intercrop produced > 1000 kg ha−1 biomass over 9 weeks, and led to a (non-significant) 10% wheat yield reduction. There was no significant effect of cover crop or temporary intercrop treatments on soil functions in the 2020 or 2021 seasons, but activities of several soil enzymes (leucine aminopeptidase, arylsulfatase and B-glucosidase; P < 0.05) and water-soluble carbon (P = 0.059) were significantly higher in the summer cover crop plots compared to control and intercrop plots in March 2022 following termination of the cover crops. These changes coincided with a significant increase in saturated hydraulic conductivity in the four-species cover crop plots in March 2022 compared to control plots. ImplicationsThe study did not provide any compelling evidence for benefits of summer cover crops over fallow in the short term (3–4 years). The relatively low cover crop biomass production over the 4-year study suggests summer cover crops are unlikely to substantially improve soil carbon levels in temperate, semi-arid cropping systems.

Host Suitability of Summer Cover Crops and Peach Rootstocks to the Peach Root-Knot Nematode, Meloidogyne floridensis.

Greenhouse experiments were conducted to determine the host suitability of ten summer cover crops and two peach rootstocks to Meloidogyne floridensis by inoculating them with 10,000 M. floridensis eggs. Brown top millet and sunn hemp were nonhosts as they did not support nematode reproduction. Buckwheat, cowpea, pearl millet, Japanese millet, and sunflower supported more than 25,000 eggs/pot, which indicated that these crops are good hosts to M. floridensis. The crops that supported poor nematode reproduction were sesame, grain sorghum, and sorghum-sudangrass, with their reproduction ranging from 219 to 7,750 eggs/pot. In addition to having many galls on the roots, the peach rootstock Guardian had 10,100 eggs on the roots and 450 second-stage juveniles in the pot, which indicated that 'Guardian' is a good host to M. floridensis. Although the nematode reproduction on MP-29 rootstock was relatively lower, the presence of many large galls on the roots indicates MP-29 is susceptible to M. floridensis. Results from the current study suggest that the employment of nonhost cover crops and poor-host rootstocks could aid in effective nematode management programs for peaches.

Economic assessment of using Bermudagrass stockpiling and annual cereal pasture to extend grazing in cow-calf operations.

Bermudagrass (Cynodon dactylon L.) stockpiling and cool-season annual pastures can extend grazing seasons in cow-calf operations and reduce winter feeding costs, but less is known about how these practices interact and their effect on producer profitability. Data from a completely randomized-design experiment in South-Central Oklahoma were collected on three grazing systems for cows and calves: bermudagrass pasture (CONTROL), stockpiled bermudagrass and interseeded cool-season pasture (SPINT), and stockpiled bermudagrass plus cropland no-till seeded with a summer cover-crop followed by cool-season annuals (SPCROP). A mixed model was used to estimate the effects of grazing system on weaning weights, total hay, and total range cubes (crude protein [CP] = 30%) fed in each system. Enterprise budgeting was used to calculate the expected net return of each system. Weaning weight did not vary between systems (P = 0.6940), resulting in similar revenues. Relative to other treatments, the quantity of cubes fed in the CONTROL system were significantly higher (P < 0.0001) while hay fed was significantly higher in the SPCROP system (P = 0.0036). Increased machinery costs, seed costs, and fertilization requirements in bermudagrass stockpiling, interseeding, and cropland production outweighed the cost savings associated with less feeding. Total costs were $446 ha-1 ($722 hd-1), $451 ha-1 ($732 hd-1), and $553 ha-1 ($895 ha-1) for the CONTROL, SPINT, and SPCROP systems, respectively. Overall, the CONTROL system was $3.13 ha-1 ($5.08 hd-1) and $98.91 ha-1 ($160.10 hd-1) more profitable than the SPINT and SPCROP systems.

Cover cropping promotes soil carbon sequestration by enhancing microaggregate-protected and mineral-associated carbon

Cover cropping can improve soil C sequestration compared to no cover cropping, but the mechanism of C sequestration in soil aggregates and minerals needs more exploration. We explored C sequestration using C fractions in soil aggregates and minerals by cover crops in a five-year old summer cover crop – winter wheat (Triticum aestivum L.) rotation system at Changwu National Agroecology Experimental Station in the Chinese Loess Plateau. Three cover crops as soybean (Glycine max L., SB), sudangrass (Sorghum sudanense (Piper) Stapf, SG), soybean and sudangrass mixture (SS) were planted during summer fallow and incorporated into the soil two weeks prior to wheat planting each year. Soil samples at 0–10, 10–20, and 20–40 cm depths were collected at wheat harvest after 5-yr and analyzed for C fractions which were coarse particulate organic C (cPOC), intra-microaggregate fine particulate organic C (iPOC), free fine particulate organic C (fPOC), and mineral-associated organic C (MOC). The iPOC and MOC are considered as protected C against mineralization. Compared to no cover crop (CK), cover crops increased large macroaggregate proportion at 0–10 cm by 18–22 %, with SS having a greater mean-weight diameter (MWD) than other treatments. Cover crops had greater MOC, iPOC, and fPOC fractions than CK in most aggregate-size classes and the bulk soil at all depths, with SS having the greatest C fractions. The MOC was greater than any other C fractions, regardless of cover crop species. Cover cropping can enhance soil aggregation and C sequestration by increasing microaggregate-protected and mineral-associated C compared to no cover cropping, resulting in improved soil C stabilization. Cover crop mixture was more effective in promoting soil aggregate stability and C fractions than single cover crop species.

Phylogenetic relatedness can influence cover crop-based weed suppression

Cover crops are plants grown to provide regulating, supporting, and cultural ecosystem services in managed environments. In agricultural systems, weed suppression services from cover crops can be an important tool to promote sustainability as reliance on herbicides and tillage for weed management has caused pollution, biodiversity loss, and human health issues. However, to effectively use weed suppression services from cover crops, farmers must carefully select species that fit within their rotations and suppress their problematic weeds. Understanding how the relatedness between cover crops and weeds affects their interactions will help farmers select cover crops for targeted weed management. The phylogenetic distance between species reflects their relatedness and was studied through a series of field experiments that compared weed suppression in winter and summer cover crops with tilled controls. This study demonstrates that cover crops can reduce up to 99% of weed biomass and alter weed community structure by suppressing phylogenetically related weed species. Results also suggest that cover crop planting season can influence weed community structure since only overwintering treatments affected the phylogenetic distance of weed communities. In an applied context, these results help develop cover crop-based weed management systems, demonstrating that problematic weeds can be managed by selecting phylogenetically related cover crop species. More broadly, this study provides a framework for evaluating weed communities through a phylogenetic perspective, which provides new insight into plant interactions in agriculture.

Recurring Rolling/Crimping Effects on Termination Effectiveness of Iron Clay Pea and Pearl Millet Warm-Season Cover Crops

Summer cover crop utilization by no-till vegetable farms is essential for continuous soil protection, especially in the southern United States where intense storms are likely to occur in hot and humid summer months. A field experiment was conducted at the National Soil Dynamics Laboratory in Auburn, AL, USA, between the summers of 2015 and 2017 to determine the effectiveness of an experimental roller/crimper in mechanically terminating summer cover crops. Iron clay peas (Vigna unguiculata, L.) planted on a sandy loam and pearl millet (Penninsetum glaucum, L.) planted on clay soil were selected to determine termination rate effectiveness in single, double, and triple rolling/crimping over the same area. Overall, termination rates for both cover crops were higher for rolling three times (71%) compared to rolling once (55%) or twice (63%). However, cover crop termination was inhibited due to rainfalls on the experimental area during the three-week evaluation period. In 2016, drought conditions and high temperatures (32.6 °C) caused biomass reduction, especially for pearl millet, of over 31% to 39% compared to 2017 and 2015. Rolling provided higher soil-water conservation compared with the non-rolled control due the cover crop mulch layer blocking sunlight, keeping the soil surface cooler and preventing water evaporation. Recurrent rolling did not cause soil compaction above the 2.0 MPa level that inhibits root growth, but changes in soil strength were dependent on the soil moisture content.

Grazing summer cover crops mix impact on carbon[sbnd]nitrogen cycling, soil water, and wheat yields

Summer fallow practice is common in the US semiarid Southern Great Plains ecoregion. Its primary objective is to store water to enhance winter wheat production for grain and grazing. Prior research on replacing fallow with legume cover crops (CC) (green manure) reported a yield loss through soil moisture depletion for winter wheat. Recent research has shown the potential of grass CC to enhance soil physical properties compared to legume CC. Cost-benefit analyses of CC make it difficult to justify their adoption. Grazing, however, offers an opportunity to mitigate CC costs. The impact of a grazed CC mix on stored soil water, CN cycling, intercropping, and wheat yields was evaluated. Although CC used soil moisture early in the growing season and nitrate+nitrite-N, they recharged soil moisture by the critical wheat seeding and dormancy-breaking periods. In the summer of 2014, net mineralization in CC increased nitrate+nitrite-N by 10-fold compared to 2013 concentrations, resulting in no significant differences in yields in 2015. Nitrate+nitrite-N was reduced by 28% in 2015 compared to the preceding year due to CC growth and net nitrate+nitrite-N immobilization in residues, resulting in 25% less yield in CC treatments in 2016 compared to no-till (NT) fallow. Grazed and ungrazed CC enhanced organic N by up to four times that in NT fallow and sequestered particulate organic N and C by 7–17% and 6–10%, respectively, in micro-aggregates. Despite reducing biomass by 56%, grazing did not differ from most ungrazed measured soil parameters, offering the potential for mitigating CC production costs.

Different cover crops have a limited impact on marketable yields and biogeochemical cycling but secondary effects on pollinators and plant-parasitic nematodes in Florida organic vegetable systems

Cover crops are typically grown during the summer in Florida’s organic vegetable systems, where they can affect nutrient cycling, soil health, and pests/pollinators. We compared the effects of five summer cover crops and a weedy fallow on marketable yields and the cycling of phosphorus, potassium, and carbon. Weed, nematode, and insect pollinator abundance were also monitored to measure any secondary impacts of cover cropping. Cover crops included monocultures of sunn hemp or sorghum sudangrass, a sunn hemp and sorghum sudangrass biculture, a three species mixture (biculture plus buckwheat), and a five species mixture (three species mixture plus cowpea and sunflower). In both 2018 and 2019, cover crops were planted in June and terminated in August, and bell peppers were grown from August until December. Marketable yields were greater with the tree and five species mixtures relative to the biculture in 2018, with no effects of cover crops on yields in 2019. Phosphorus and potassium accumulation was typically greater with cover crops than in the weedy fallow, but cover crops did not affect pepper nutrient accumulation or soil concentrations. Similarly, differences in carbon accumulation (lowest in sorghum sudangrass monoculture and weedy fallow) did not affect soil organic matter, soil total carbon or permanganate-oxidizable carbon. When analyzed as part of a radar plot analysis, cover crops helped manage summer weeds and root-knot nematodes in 2019, but the sorghum sudangrass monoculture increased sting nematodes; only the three and five species mixtures benefitted pollinators as buckwheat was the only cover crop that flowered in this study. Overall, cover crops had a limited effect on marketable yields and biogeochemical cycling but had more important secondary effects on pests and pollinators.

Cover cropping impacts on soil water and carbon in dryland cropping system.

Incorporating cover crops into the rotation is a practice applied across many parts of the globe to enhance soil biological activities. In dryland farming, where crop production is highly dependent on rainfall and soil water storage, cover cropping can affect soil water, yet its effects on soil hydrological and biological health require further investigation. The objective of this study was to evaluate the effect of different timing of summer sorghum cover crop termination on soil water, total and labile organic carbon, arbuscular mycorrhizal fungi and their mediating effects on wheat yield. Through on-farm trial, soil characteristics along with wheat biomass, yield and grain quality were monitored. In comparison with the control (fallow), the early terminated cover crop was the most effective at retaining greater soil water at wheat sowing by 1~4% in 0-45cm soil profile. An increase in water use efficiency, yield and grain protein by 10%, 12% and 5% was observed under early termination. Under late terminated summer cover crop, there was 7% soil water depletion at wheat planting which resulted in 61% decline in yield. However, late-terminated cover crop achieved the greatest gain in soil total and particulate organic carbon by 17% and 72% and arbuscular mycorrhizal fungal Group A and B concentration by 356% and 251%. Summer cover crop incorporation resulted in a rapid gain in labile organic carbon, which constituted hotspots for arbuscular mycorrhizal fungi growth, conversely, fungal activities increased labile organic carbon availability. The combined effect of increased soil water at sowing and over the growing season, organic carbon, and microbial activities contributed to greater yield. The findings suggest that summer cover cropping with timely termination can have implications in managing soil water at sowing time and enhancing soil water storage during the season, soil carbon, and facilitating microbial activities while enhancing productivity in the dryland cropping system.

Rooting depth and water use of summer cover crops in a semi-arid cropping environment

Summer cover crops could add biomass (groundcover), fix nitrogen (legumes) and create biopores in Mediterranean-type cropping systems, but soil water use, especially from the subsoil, may reduce yields of the following winter cash crop. Research on rooting patterns/depth of summer cover crops and consequences for soil moisture storage in Mediterranean-type cropping systems is limited. To assess the rooting patterns and water use of a range of legume (sunn hemp, cowpea, mung bean, lablab), non-legume broadleaf (buckwheat, radish) and cereal (millet) summer cover crops in a Mediterranean-type environment, two field trials (2020 and 2021) and one glasshouse experiment were conducted. Root distribution, rooting depth, root diameter, water use and shoot biomass were evaluated. Millet produced the most biomass of any single species in the field (around 4 t ha-1) and had significantly higher water use efficiency (8.4 g L-1) than all legumes (4–6 g L-1). Millet and buckwheat exhibited dense, shallow root systems that exploited water in the profile surface, while legumes, particularly cowpea, had greater root density in the subsoil, resulting in greater subsoil water use. All legumes had significantly greater average root diameter (0.5–0.7 mm) below 40 cm than millet, buckwheat and radish (0.2–0.4 mm). Dual species mixes with millet or cowpea generally led to increased biomass production and increased rooting and water use in deeper soil layers compared to single species cover crops. The results suggest that millet may be preferable in seasons where the key objective of a summer cover crop is to provide ground cover with minimal water use, whereas in wetter seasons, legumes may be beneficial in drying the subsoil and potentially creating biopores. Ultimately, all cover crops significantly reduced stored soil water compared to a chemical fallow, which will likely affect cash crop yield in many seasons.

Interseeded cover crops did not reduce silage corn performance in the sandy loam soils of South Carolina

AbstractA major concern with interseeding summer cover crops alongside cash crops is the possibility of cover crops competing with the main crop for water and nutrients and thus, reducing the main crop yields. We conducted on‐farm trials in the sandy loam soils of the upstate of South Carolina in 2020 and 2021 to evaluate the effect of white clover (Trifolium repens L.), buckwheat (Fagopyrum esculentum Moench), and pigeon pea (Cajanus cajan (L.) Millsp.) and their mixture interseeded at V4, V7, and V10 corn growth stages on silage corn performance and soil moisture content. We found that none of the cover crops affected silage corn height and aboveground biomass production regardless of the interseeding time. Further, the volumetric water content in the upper 20‐cm soil profile was not decreased by cover crops irrespective of their interseeding time. At physiological maturity, corn height, aboveground biomass, and volumetric water content ranged between 131 and 163 cm, 9 and 23 Mg ha−1, and 10% and 22%, respectively, in season‐1 and between 181 and 216 cm, 0.48 and 1.03 Mg ha−1, and 10% and 17%, respectively, in season‐2 when interseeded with cover crops. When cover crops were not interseeded, the average corn height, aboveground biomass, and volumetric water content values were 152 cm, 13 Mg ha−1, and 13%, respectively, in season‐1 and 204 cm, 0.7 Mg ha−1, and 14%, respectively, in season‐2. These results would encourage farmers who want to consider cover crop interseeding with corn in the regional production systems.

Profitability of grazing no‐till established winter cereal pasture and summer cover crops

AbstractNo‐till establishment (NT) and cover crops (CC) are two agricultural practices promoted to reduce externalities with clean‐till (CT) and fallow practices, better soil health, and improve producer profitability. Some research reports economic value for NT on water‐limited cropland acres, helping to advance farmer adoption; however, economic research associated with CC is limited. This study determined the economics of NT and CC for small grain pasture grazing systems in the Southern Great Plains (SGP). Data from a 5‐year, completely randomized design (CRD) grazing experiment were used in mixed‐effects regression models to estimate the effects of establishment method (CT and NT) and either summer fallow (SF) or summer CC on average daily gain (ADG), steer grazing days (SGD), and total gain (TG) ha−1. Enterprise budgeting was used to determine the relative net benefits of CTSF, NTSF, CTCC, and NTCC systems. Winter TG was the same for CTSF and NTSF systems; however, the NTSF realized 39 and 21 kg TG ha−1 more (p ≤ 0.01) than the CTCC and NTCC systems, respectively. TG on CC was 11 kg ha−1 greater (p ≤ 0.01) for NT than CT. NT realized lower costs for machinery labor and fuel than CT, giving it an economic advantage; however, revenues from grazing CC did not outweigh the additional costs of seed, fuel, and chemical applications. Overall, the NTSF system produced US$34.04 ha−1 greater net returns than the next best system. This result was not sensitive to relative changes in prices of glyphosate, labor, fuel, or cover crop seed.

Opportunities and Challenges for Cover Cropping in Sustainable Agriculture Systems in Southern Australia

Southern Australian farming systems operate predominantly under Mediterranean climatic conditions, which limit the choice of cover crops suitable for enhancement of ground cover and soil moisture retention, erosion control, atmospheric soil nitrogen (N) fixation, and weed suppression between cash crop rotations. Given that the successful establishment of cover crops is climate-driven and also influenced by edaphic factors such as soil pH and salinity, there has been increased interest by southern Australian producers in identifying potential cover crop species well adapted to specific Australian farming systems, which provide vital ecosystem services and sustainable economic benefits through the improvement of soil properties. This review summarises recent findings on cover crop inclusion in diverse farming systems in southern Australia, including continuous and mixed broadacre cropping as well as viticulture and horticulture systems, to identify opportunities and limitations related to their use. Cover crop inclusion in viticulture and pasture systems with lower moisture stress was observed to benefit the subsequent cash crop through enhanced production potential. Long-term, multi-site field experimentation incorporating summer cover crops in winter crop rotations showed that cover crops enhanced ground cover and soil water infiltration in some locations across southern Australia while sometimes increasing winter crop yield, suggesting that soil type and regional climatic conditions greatly influenced the delivery of multiple cover crop benefits. Collectively, these studies have suggested a need for longer-term field evaluations using multiple cover crop species and investigations of termination options under varying environmental and soil conditions to better quantify the legacy effects of cover crops.

Evaluation of Nitrogen and Cropping System Management in Continuous Winter Wheat Forage Production Systems

In the central Great Plains, winter wheat is used for over-winter grazing for cattle and sheep until the late spring months, when livestock are moved to grass pasture. As the popularity of summer cover crops increases, interest in their use in forage production systems increases as well. There is specific interest in the opportunity to increase productivity by the inclusion of a crop grown in the fallow season of winter wheat fields. The intensification of systems in a resource (water and/or nitrogen) limited region could decrease winter wheat forage production influencing a system’s ability to sustain continuous forage production. Nitrogen (N) management could be effective in mitigating negative impacts on winter wheat. The objective of this study is to evaluate the influence of different summer forage crop species and different N management strategies in a multi-year continuous winter wheat forage production system in the central Grain Plains. Increased production of dry matter and crude protein was observed by implementing summer forage crops into a winter wheat forage system. A deleterious effect of summer crops compared to traditional fallow periods was observed but mitigated by the split application of N even compared to the same rate applied at pre-plant.