Cover Crop Mixtures Research Articles

Ecosystem service delivery by cover crop mixtures and monocultures is context dependent

AbstractWhile cover crops and mixtures are increasingly used to provide ecosystem services in agroecosystems, some fundamental questions remain about how cover crop performance and composition vary in different conditions, limiting optimal cover crop use. We conducted a field experiment at a research farm in New York, including a subset of treatments in three working farm fields. We selected two common cover crops, hairy vetch (Vicia villosa Roth), a legume, and common wheat (Triticum aestivum L.), a grass, with multiple cultivars of each. We looked at the effect of cover crop composition spanning intraspecific and grass–legume mixtures on five ecosystem services: cover crop productivity, weed suppression, total biomass nitrogen, soil N retention, and long‐term N supply via legume fixed N. We did not find intraspecific diversity to have an effect on any ecosystem services we measured, nor was that response context dependent. We did observe significant ecosystem service improvements in the grass–legume mixture, though this was context dependent and the performance of the mixture varied relative to the monocultures at different farm sites. Regardless of this interaction however, the grass–legume mixture was as good as or better than either monoculture for all services and sites, except soil N accrual at one site. Consequently, increasing complexity in cover crops through grass–legume mixtures is a low risk practice that may have the potential to deliver ecosystem service outcomes greater than those of monocultures across a range of growing conditions.

Prevalence of Early- and Late-Season Pest Damage to Corn in Cover Crop-Based Reduced-Tillage Organic Systems.

In organic agronomic cropping systems, the use of synthetic insecticides and transgenic varieties are prohibited and producers rely mainly on biological control, tillage, crop rotation, and other cultural practices to manage pests. We measured damage to organic corn (Zea mays L.) from multiple invertebrate pests, including slugs (Gastropoda: Mollusca), European corn borer (Ostrinia nubilalis Hübner), corn earworm (Helicoverpa zea Boddie), and fall armyworm (Spodoptera frugiperda Smith), early and late in the growing season in four cropping systems that varied in tillage frequency and intensity and in winter cover crop species. Specific management tactics included two cover crop mixtures preceding corn, the use of a roller-crimper or tillage to terminate cover crops preceding corn, and the establishment of interseeded cover crops after corn emergence. Prevalence of early-season damage was high, but severity of damage was very low and unrelated to corn yield. The proportion of corn plants affected by chewing pests early in the season was lower in plots in which tillage compared to a roller-crimper was used to terminate cover crops. Cropping system did not affect the numbers of late-season caterpillar pests or corn yield. Predation by natural enemies appeared to effectively maintain damage from chewing pests below yield-damaging levels. These results support the inclusion of winter and interseeded cover crops in organic agronomic crop rotations to gain environmental benefits without increasing risks of damage by insect pests.

Soil microbial biomass and community composition as affected by cover crop diversity in a short‐term field experiment on a podzolized Stagnosol‐Cambisol

AbstractBackground: Cover cropping appears as a useful land management practice with numerous benefits for ecosystem functions.Aim: The objectives of this study were to determine the effects of different winter cover crops on soil microbial biomass, activity, and community composition in intensively managed agriculture systems as function of cover crop diversity.Methods: For this purpose, an on‐farm experiment was conducted at a podzolized Stagnosol‐Cambisol during seven months growing oil radish as single cover crop and five different cover crop mixtures comprising 5 to 13 plant species. A fallow treatment was used as control. Phospholipid fatty acids were used to determine the soil microbial biomass and soil microbial community composition. Basal respiration of the soil microorganisms was measured as a proxy for microbial activity.Results: The results show that none of the cover crop mixture could increase soil organic carbon or total nitrogen content. Three cover crop mixtures and oil radish as single cover crop significantly increased soil microbial biomass by about 50% and all of the investigated cover crops significantly increased microbial respiration and metabolic quotient by 50–150%. Only highly diverse cover crop mixtures significantly increased individual microbial groups such as Gram‐positive and Gram‐negative bacteria, actinobacteria, and saprotropic and mycorrhizal fungi by about 20% compared to the control. However, the ratio of fungi to bacteria was not influenced by any of the cover crop mixtures under study.Conclusion: These findings corroborate that aboveground plant diversity is linked to belowground microbial diversity.

Cover crops during transition to no-till maintain yield and enhance soil fertility in intensive agro-ecosystems

• No-till (NT) with cover crops (CCs) maintains yield of wheat, maize and soybean. • NT-CCs increased SOM from 20% to 30% compared to CT in the 0-30 cm soil layer. • NT-CCs increased STN from 21% to 28% compared to CT in the 0-30 cm soil layer. • Replacing CT with NT and winter CCs enhances soil fertility in the long-term. Introducing no-till and cover crops in arable agro-ecosystems leads to the restoration of soil fertility, through the increase of soil organic matter (SOM), soil total nitrogen (STN), and available phosphorus (P), therefore maintaining or enhancing crop yield and reducing costs. Although the effects of those practices have been widely examined, many studies show conflicting results and little is known about the combined effects of no-till (NT) and cover crops (CCs) under intensive arable cropland in the Po Valley (Northern Italy). The objectives of this study were: (i) to evaluate if NT management coupled with CCs negatively affects yields during the transition period and how yields evolve; (ii) to assess SOM, STN, and P dynamics in the 60-cm soil depth layer; and (iii) to evaluate the effects of different types of winter cover crops on yield and soil parameters. A six-year field experiment was established in Piacenza, on a silty-clay soil under temperate climate conditions. The crop sequence was: winter wheat, maize, maize, soybean, winter wheat, and maize. The four experimental treatments were: (1) conventional tillage (CT) as control; (2) NT with CC of rye (NT-R); (3) NT with CC of hairy vetch (NT-V); and (4) NT with a mixture of CCs (rye, hairy vetch, crimson clover, Italian rye-grass and radish) [NT-M]). Dry biomass yield of CCs ranged between 2.2 and 3.1 Mg ha −1 for rye; 1.9 and 3.0 Mg ha −1 for hairy vetch; and 1.9 and 3.2 Mg ha −1 for mixture. In the present study, yields of winter wheat, maize, and soybean were generally not reduced with NT-CCs since the first year after conversion. The different composition and thickness of cover crop mulch showed an opposite yield response to rainfall pattern: under NT-R, a negative correlation was observed between grain yield and rainfall, while under NT-V this correlation was positive. After six years, SOM and STN concentrations in the 0-30 cm soil layer increased in NT-CCs. SOM concentration was +30%, +23% and +20% higher than CT for NT-R, NT-M and NT-V, respectively. STN was +28% higher under NT-R and NT-V, and +21% higher under NT-M, than CT. Conversely, P concentration was not influenced by the NT-CCs system, although we observed a tendency to increase under NT-V. In the 30-60 cm soil, layer, the tillage systems did not affect SOM and STN. We concluded that introducing NT with winter CCs into intensive arable agricultural systems is an effective strategy for enhancing soil fertility in fine-textured soils under temperate climates, without penalizing yields.

Cover crop and cereal straw management influence the residual nitrogen effect

Cover crops (CC) may play an essential role in the recycling of nutrients in organic farming systems with cereals. Harvest time of cereals and management of straw in the field can affect the growth of CC and subsequent nitrogen (N) fertiliser replacement value (NFRV) in the following crop. This study investigates 1) the effect of harvest time, 2) cutting height of straw and 3) straw removal from the main crop on CC growth, composition, uptake and NFRV in the following crop and 4) the effect of CC harvest in autumn on the NFRV in the succeeding crop. A CC mixture of mainly red clover, with chicory and ryegrass was sown under a spring barley crop in 2017, and replicated in 2018. Four strategies of barley harvest were conducted: 1) early harvest as whole crop or 2) early harvest of the upper parts only, 3) at maturity with straw removed or 4) at maturity with straw left on the field surface. Subsequently, CC and high stubbles of left straw were harvested and removed in autumn in half of the field replicates. The residual effect was measured in spring barley in the succeeding year. The CC aboveground biomass dominated by the clover had an N uptake for both years of 40−77 kg N ha−1. Variability was significant between years but not caused by the harvest time or by straw management. In the succeeding year, residues from barley and CC could replace 61−85 kg N ha−1 of mineral N fertiliser, which were mostly derived from CC roots and stubble. High straw stubble left (40 cm length) significantly reduced the NFRV of CC shoots by 20%. Root residues (including barley and CC roots) contributed a substantial N supply to the following crop irrespective of aboveground CC biomass. The availability of N derived from CC shoot mineralisation differed significantly in the two years and was also influenced by straw left from the previous crop.

Winter-hardy vs. freeze-killed cover crop mixtures before maize in an organic farming system with reduced soil cultivation

The advantages and disadvantages of a winter-hardy vs. a freeze-killed cover crop mixture combined with reduced soil cultivation to a following maize crop were studied on an organic farm in Lower Austria in two consecutive experiments. Effects on soil inorganic nitrogen contents, weed density and the yield of a following maize crop were assessed. The winter-hardy compared with freeze-killed cover crop mixture, both consisting of legumes and non-legumes, reduced soil inorganic nitrogen contents over winter, leading to a reduced nitrate leaching risk, whereas the yield of a following grain maize crop was not significantly affected. Weed density was high in both cover crop treatments, presumably due to the continued reduced, non-inverting soil cultivation on the farm, and higher in the winter-hardy cover crop treatment at one of the assessment dates. Combined with an adapted soil cultivation, both the winter-hardy and the freeze-killed cover crop mixture were suitable before grain maize in this organic farming system with non-inverting soil cultivation under moderately dry site conditions, but the winter-hardy cover crop mixture seems advantageous because it reduces the nitrate leaching risk.

Fungal community shifts in soils with varied cover crop treatments and edaphic properties

Cover cropping is proposed to enhance soil microbial diversity and activity, with cover crop type affecting microbial groups in different ways. We compared fungal community compositions of bulk soils differing by cover crop treatment, season, and edaphic properties in the third year of an organic, conventionally tilled rotation of corn-soybean-wheat planted with winter cover crops. We used Illumina amplicon sequencing fungal assemblages to evaluate effects of nine treatments, each replicated four times, consisting of six single winter cover crop species, a three-species mixture, a six-species mixture, and fallow. Alpha-diversity of fungal communities was not affected by cover crop species identity, function, or diversity. Sampling season influenced community composition as well as genus-level abundances of arbuscular mycorrhizal (AM) fungi. Cover crop mixtures, specifically the three-species mixture, had distinct AM fungal community compositions, while cereal rye and forage radish monocultures had unique Core OTU compositions. Soil texture, pH, permanganate oxidizable carbon, and chemical properties including Cu, and P were important variables in models of fungal OTU distributions across groupings. These results showed how fungal composition and potential functions were shaped by cover crop treatment as well as soil heterogeneity.

Winter cover crop production and water use in Southern Great Plains cotton

AbstractCover crops can provide several ecosystem services in agricultural cropping systems. Benefits may be enhanced with increasing cover crop biomass production. In water‐limited environments, feasibility of cover crop germination and production is not always certain. This study was conducted to determine differences in biomass production, water use, and water use efficiency (WUE) between monoculture cover crops and a mixture at Chillicothe, TX, in the Southern Great Plains under rainfed conditions in a continuous cotton (Gossypium hirsutum L.) cropping system over a 6‐yr period. Evaluated cover crops included Austrian winter pea (Pisum sativum L.), crimson clover (Trifolium incarnatum L.), hairy vetch (Vicia villosa L.), hard red winter wheat (Triticum aestivum L.), and a grass/broadleaf mixture. Although cover crops were planted after optimum planting dates and under varying climatic conditions, biomass production was 2863, 2480, and 2301 kg ha−1 for the mixture, pea, and vetch, respectively. Peas and the mixture were the most consistent, producing significantly greater biomass than wheat and clover but not more than vetch. The mixture resulted in greater WUE than wheat. Clover resulted in reduced biomass production and WUE than vetch, pea, and the mixture over the study period. A cover crop mixture did not produce significantly greater biomass or significantly increase water use efficiency compared with vetch and pea. Under dryland conditions, peas, vetch, and a mixture were shown to be viable cover crop options in Southern Great Plains cotton systems, performing as well as a wheat cover crop.

Direct seeding associated with a mixture of winter cover crops decreases weed abundance while increasing cash-crop yields

In this study, we aim to evaluate the respective and combined effect of soil tillage reduction and winter cover crops (CCs) on both weed species recruitment and sunflower (Helianthus annuus) yields. By controlling the species composition and propagule pressure of weeds, we tested four soil cover rotation treatments with winter CCs (either Camelina sativa or a winter CC-mix of Leguminosae-Brassicaceae) or nothing (control) followed by a sunflower culture or nothing (control) in combination with two soil preparation treatments (reduced tillage vs. direct seeding) in a randomized complete block design with three replicates per treatment. Our experiment thus comprised 24 experimental units (4 m × 1 m). In each experimental unit, seeds of 40 weed species were sown in May 2017 and seedling emergence was subsequently monitored in mid-July, August and September 2017. We used generalized linear models to analyze the effect of soil cover rotation, soil preparation and the two-way interaction term on species richness, abundance (i.e. number of individuals) and sunflower yield. We additionally used generalized linear mixed-effects models to analyze species relative abundance changes throughout the monitoring period and relative to an exhaustive vegetation survey performed at the beginning of the experiment. Our results show that reduced tillage may increase weed species richness under some circumstances, as well as the abundance of two annual species (i.e. Viola arvensis and Fumaria officinalis). Winter CC-mix reduces the abundance of the most dominant weed species (i.e. the grass Echinochloa crus-galli) while increasing the average weight of sunflower seeds per stem. Irrespective of the tillage treatment, we found that C. sativa favors the presence of patrimonial weed species at the expense of noxious species. We conclude that direct seeding associated with winter CC-mix allows controlling weed abundance while increasing cash-crop yields, and thus meets criteria for a sustainable agriculture.

Cover crop impact on irrigated cotton yield and net return in the southern Great Plains

AbstractCover crops have the potential to increase ecosystem services of cropping systems, although mixed results have been found throughout the U.S. Great Plains. Crop performance and economic returns are often used by producers to gauge the feasibility of adoption. In addition, soil moisture use by cover crops is a concern in semiarid environments. The objective of this research was to determine the impact of cover crops on cotton (Gossypium hirsutum L.) yield and economic return compared with conventional practices in pivot irrigated systems of the southern Great Plains. A 6‐yr study was conducted at the Texas A&M AgriLife Chillicothe Research Station evaluating the following treatments: (i) conventional till (CT); (ii) no‐till (NT); (iii) NT with winter wheat (Triticum aestivum L.) cover crop (NT‐W); and (iv) NT with a multi‐species cover crop mixture (NT‐M). Cotton yields, expenses, and returns were determined over a 6‐yr period (2013–2018). No significant treatment effect was determined for crop yield. Compared to NT, lint yields were increased 9.5% by NT‐M and 9.4% by NT‐W. Cover crop treatments significantly increased total costs compared to NT. However, net returns were 12% greater for NT‐W and 8% greater for NT‐M compared to NT. Over the 6‐yr study, NT‐M did not provide an agronomic or economic advantage over NT‐W. Under irrigated conditions in the southern Great Plains, cover crops were implemented without negatively affecting lint yield or net returns in continuous cotton systems at seeding rates of 34 kg ha–1.

Impact of Cover Crops on the Soil Microbiome of Tree Crops.

Increased concerns associated with interactions between herbicides, inorganic fertilizers, soil nutrient availability, and plant phytotoxicity in perennial tree crop production systems have renewed interest in the use of cover crops in the inter-row middles or between trees as an alternative sustainable management strategy for these systems. Although interactions between the soil microbiome and cover crops have been examined for annual cropping systems, there are critical differences in management and growth in perennial cropping systems that can influence the soil microbiome and, therefore, the response to cover crops. Here, we discuss the importance of cover crops in tree cropping systems using multispecies cover crop mixtures and minimum tillage and no-tillage to not only enhance the soil microbiome but also carbon, nitrogen, and phosphorus cycling compared to monocropping, conventional tillage, and inorganic fertilization. We also identify potentially important taxa and research gaps that need to be addressed to facilitate assessments of the relationships between cover crops, soil microbes, and the health of tree crops. Additional evaluations of the interactions between the soil microbiome, cover crops, nutrient cycling, and tree performance will allow for more effective and sustainable management of perennial cropping systems.

English

The economics of using mixtures of a vegetable cowpea, Vigna unguiculata subsp. sesquipedalis L., known locally as ‘Akidi’ (A) in Eastern Nigeria, melon (M) and sweet potato (S) Ipomea batatas for weed management in maize were evaluated between 2007 and 2009 in Taraba State, College of Agriculture Teaching and Research Farm, Jalingo, Treatments include 20,000(1), 30,000(2) and 40,000(3) stands/ha of AM (AM1, AM2, AM3), AS (AS1, AS2, AS3), MS (MS1, MS2, MS3) and AMS (AMS1, AMS2, AMS3). Weeded (3+6 WAP) (C1) and unweeded (C2) checks served as control replicated three times in a randomized complete block design. Partial budget analysis was used to obtain the level of profitability. The cost of production in all the mixtures having sweet potato was slightly higher (₦61,740 .00-₦67,340.00) than the AM treated plots (₦51,460.00-₦52,880.00) in the three year production. The gross benefit of ₦205,490.00, ₦199,920.00, ₦164,940.00 and ₦130,270.00 was realized respectively from MS, AS, AMS and AM treated plots compared with ₦154,980 in the hand weeded plots. Over the three years, the net benefit was in the order MS> AS> AMS > C1>AM , which resulted in 24.33, 23.22, 18.1, 17.57 and 13.67 times net profit when compared to the unweeded, respectively. Key words: Profitability, biological weed management, maize, cover crop mixtures.

Drill and broadcast establishment methods influence interseeded cover crop performance in organic corn

AbstractOrganic grain producers are interested in interseeding cover crops into corn (Zea mays L.) in regions that have a narrow growing season window for post-harvest establishment of cover crops. A field experiment was replicated across 2 years on three commercial organic farms in Pennsylvania to compare the effects of drill- and broadcast-interseeding to standard grower practices, which included post-harvest seeding cereal rye (Secale cereale L.) at the more southern location and winter fallow at the more northern locations. Drill- and broadcast-interseeding treatments occurred just after last cultivation and used a cover crop mixture of annual ryegrass [Lolium perenne L. ssp. multiflorum (Lam.) Husnot] + orchardgrass (Dactylis glomerata L.) + forage radish (Raphanus sativus L. ssp. longipinnatus). Higher mean fall cover crop biomass and forage radish abundance (% of total) was observed in drill-interseeding treatments compared with broadcast-interseeding. However, corn grain yield and weed suppression and N retention in late-fall and spring were similar among interseeding treatments, which suggests that broadcast-interseeding at last cultivation has the potential to produce similar production and conservation benefits at lower labor and equipment costs in organic systems. Post-harvest seeding cereal rye resulted in greater spring biomass production and N retention compared with interseeded cover crops at the southern location, whereas variable interseeding establishment success and dominance of winter-killed forage radish produced conditions that increased the likelihood of N loss at more northern locations. Additional research is needed to contrast conservation benefits and management tradeoffs between interseeding and post-harvest establishment methods.

Are cover crop mixtures better at suppressing weeds than cover crop monocultures?

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

A meta-analysis of global cropland soil carbon changes due to cover cropping

Including cover crops within agricultural rotations may increase soil organic carbon (SOC). However, contradictory findings generated by on-site experiments make it necessary to perform a comprehensive assessment of interactions between cover crops, environmental and management factors, and changes in SOC. In this study, we collected data from studies that compared agricultural production with and without cover crops, and then analyzed those data using meta-analysis and regression. Our results showed that including cover crops into rotations significantly increased SOC, with an overall mean change of 15.5% (95% confidence interval of 13.8%–17.3%). Whereas medium-textured soils had highest SOC stocks (overall means of 39 Mg ha−1 with and 37 Mg ha−1 without cover crops), fine-textured soils showed the greatest increase in SOC after the inclusion of cover crops (mean change of 39.5%). Coarse-textured (11.4%) and medium-textured soils (10.3%) had comparatively smaller changes in SOC, while soils in temperate climates had greater changes (18.7%) than those in tropical climates (7.2%). Cover crop mixtures resulted in greater increases in SOC compared to mono-species cover crops, and using legumes caused greater SOC increases than grass species. Cover crop biomass positively affected SOC changes while carbon:nitrogen ratio of cover crop biomass was negatively correlated with SOC changes. Cover cropping was associated with significant SOC increases in shallow soils (≤30 cm), but not in subsurface soils (>30 cm). The regression analysis revealed that SOC changes from cover cropping correlated with improvements in soil quality, specifically decreased runoff and erosion and increased mineralizable carbon, mineralizable nitrogen, and soil nitrogen. Soil carbon change was also affected by annual temperature, number of years after start of cover crop usage, latitude, and initial SOC concentrations. Finally, the mean rate of carbon sequestration from cover cropping across all studies was 0.56 Mg ha−1 yr−1. If 15% of current global cropland were to adopt cover crops, this value would translate to 0.16 ± 0.06 Pg of carbon sequestered per year, which is ~1–2% of current fossil fuels emissions. Altogether, these results indicated that the inclusion of cover crops into agricultural rotations can enhance soil carbon concentrations, improve many soil quality parameters, and serve as a potential sink for atmosphere CO2.

The cover crop termination choice to designing sustainable cropping systems

Abstract The use of winter cover crops (CCs) in annual rotations is a tool to increase agroecosystem sustainability. To optimize their benefits, the choice of how to terminate CCs in spring is crucial, because this decision may lead to differences in soil–plant variables and affect cash crop productivity. The use of a roller-crimper is an emerging option in both conservation and organic agriculture but its adoption in Mediterranean regions is still rare. In this work the objective was to identify best CC termination practices to maximize benefits and increase agro-ecosystem resilience. To this end a field experiment with a barley/vetch (Hordeum vulgare L. / Vicia villosa L.) CC mixture followed by an irrigated corn (Zea mays L.) was conducted in Central Spain in three consecutive years. Each year, three CC termination methods (roller-crimper, glyphosate + roller-crimper, and CC residue incorporation) and four post-emergence operations to reduce weed pressure in summer (post-emergence herbicide, inter-row cultivator, the combination of the two, or without operation) were compared. The effect on the spring soil water content and temperature, weed control, soil inorganic N and the corn grain yield and N content were evaluated. Energy and economic analyses were conducted. An ineffective CC termination by roller-crimper was overcome when using glyphosate or post-emergence herbicides. However, the roller-crimper was less dependent on post-emergence operations than residue incorporation to achieve proper weed control and attain good productivity. The results showed that in early corn growth stages, roller-crimper use enhanced the soil’s water conservation and decreased soil temperature compared to CC residue incorporation. Moreover, the energy cost was lower for roller-crimper termination. Our findings suggest that the roller-crimper increases the environmental sustainability in Mediterranean regions, but farmers may encounter economic risks. Further research is needed to find proper conditions that maximize the potential of this CC termination method under Mediterranean conditions.

Interseeding cover crops in corn

AbstractFarmers benefit from ecosystem services that cover crops provide, but time constraints limit the opportunity to seed cover crops following corn (Zea mays L.) harvest in the upper Midwest. Interseeding cover crops in corn during the early vegetative growth stages lengthens the cover crop growing season; however, cover crops may have difficulty establishing in standing corn, or conversely, compete with corn and reduce yield. The objectives of this research were to determine cover crop establishment when broadcast interseeded in corn from the V2–V7 growth stages, suppression of weeds by cover crops, and effects of cover crops on corn grain yield. Annual ryegrass (Lolium multiflorum Lam.), crimson clover (Trifolium incarnatum L.), oilseed radish (Raphanus sativus L.), and a three‐species mixture were interseeded in four site‐years in Michigan. Annual ryegrass density was highest compared with oilseed radish and crimson clover 30 d after interseeding and at harvest in October. Cover crop density was highest at the V4–V7 interseeding timings. Annual ryegrass produced more fall biomass (186 kg ha−1) compared with crimson clover (112 kg ha−1), and fall biomass was greatest at the V2, V3, and V5 interseeding timings. Spring biomass was 384 and 180 kg ha−1 for annual ryegrass and the cover crop mixture, respectively; these treatments reduced winter annual weed biomass. Corn grain yield was unaffected by cover crops at any interseeding timing. Crimson clover did not establish well in this experiment. Annual ryegrass and oilseed radish interseeded in V2–V7 corn did not reduce corn grain yield.

Cover crop diversity for weed suppression and crop yield in a corn–soybean production system in Tennessee

AbstractWeed communities may potentially reduce row‐crop yields resulting in a loss of revenue for producers. Studies have reported a decrease in the efficacy of chemical methods of weed control due to increased weed resistance. With the goal of reducing reliance on chemical weed control and promoting sustainable crop production in mind, we evaluated different winter cover crop (CC) types (single‐, double‐, and multi‐species) and CC planting methods (broadcasting vs. drilling) on CC and weed groundcover and row‐crop yield in a no‐till corn (Zea mays L.)–soybean [Glycine max (L.) Merr.] rotation system in Tennessee from 2013 to 2017. Our results showed that winter CC reduced spring weed ground coverage by 64–76% compared with winter fallow with no herbicide application. A five‐species CC mixture increased soybean yields by 6 to 8.5% across seeding method treatments compared with other CC treatments and winter fallow. This yield increase was more visible in a drought year. Corn, grown in years with normal weather patterns, did not show a yield response to CC types. From this study, cover cropping was found to be an effective strategy for weed control compared with leaving the field fallow without herbicide application following row‐crop harvest; however, no consistent species‐specific trends were observed on weed suppression and row‐crop yield. Future research should focus on understanding CC species composition and biomass production in double‐ and multi‐species mixtures from this field experiment to draw robust conclusions on agronomic responses of individual CC species and planting methods.

Cover Crop Mixtures Effects on Soil Physical and Chemical Properties in Japan

Cover Crop Mixtures Effects on Soil Physical and Chemical Properties in Japan

Hairy Vetch and Triticale Cover Crops for N Management in Soils

Over-application of fertilizer to cropland adversely affects both environmental and agricultural ecosystems. This study examined whether planting a legume-based winter cover crop mix offsets fertilizer application via natural nitrogen inputs. The influence of the cover crop mixture on available nutrients was also assessed. Hairy vetch (Vicia villosa) and winter triticale (×triticosecale) cover crops were planted in fall and terminated in May. Soil fertility data was collected before and after planting the winter cover crop to determine the effect on fixing nitrogen and soil phosphorus, potassium and organic matter levels. Increases of soil ammonium were observed in plots with cover crop treatments. A triticale-hairy vetch cover crop mix was successful at scavenging P for future crops and appears to hold promise for long-term soil fertility benefits.