Cover Crop Mixtures Research Articles

The LTAR Integrated Common Experiment at Southern Plains.

The Southern Plains (SP) is one of 18 Long-Term Agroecosystem Research network sites that combine strategic research projects with common measurements across multiple agroecosystems. Projects at the SP site focus on the use of indicator measurements to aid in assessment of land and nutrient management's impact on soil health, water quality, carbon and water balances, and forage biomass-quality in diversified, adaptive crop-livestock systems designed to overcome shifts in natural resources and climate. The prevailing treatment is tilled winter wheat (Triticum aestivum L.) that is grazed, hayed, harvested for grain, or grazed and harvested for grain. The alternative treatment is year-round annual cover crop forage mixes for cattle (Bos taurus) production planted in fall and spring under conservation tillage management. The area is subject to variable weather and climatic shifts that reduce the potential to diversify forage crops and limit grazing in southern tall grass prairies and small grain systems. Incorporation of fertilized, rain-fed, annual cool and warm season mixtures of cover crops could fill forage gaps. The presence of year-round ground cover reduces sediment and nutrient loading to surface waters while enhancing soil health and water holding capacity. Tools to aid agricultural producers and land and water resource managers have been developed and implemented to determine how climate, topography, and varying conservation management practices alter hydrological structures, greenhouse gas emissions, water usage, and soil resources.

Reduced canopy cover and development compromises weed suppression by buckwheat in cover crop mixtures

Buckwheat (Fagopyrum esculentum Moench) is a common cover crop typically grown for its rapid establishment and superior weed suppression. One challenge of incorporating buckwheat into crop rotations, however, is its short generation time, which requires in-season management to prevent viable seed production and volunteers in subsequent crops. Mixing buckwheat at reduced seeding rates with other cover crop species is one way for producers to reduce volunteer potential; however, this may compromise weed suppression. To investigate mechanisms behind buckwheat weed suppression and how using buckwheat in mixtures can affect suppression, we collected a series of morphological measurements in buckwheat monocultures and in three, two-way and four, three-way cover crop species mixtures and modeled their response over the growing season. We found that while buckwheat height and relative growth rate were unaffected with increasing species richness, there was a significant reduction in maximum leaf area index (3.75 vs. 2.85 vs. 2.82 cm2 cm-2) in mixture. Buckwheat monocultures provided superior season-long weed suppression compared to mixtures (85% vs. 53% vs. 50%). Principal component analysis showed that increased height and leaf area index values were associated with greater weed suppression. The link between reduced leaf area index and weed suppression in mixtures compared to buckwheat monocultures suggests that the rapid leaf development and canopy cover associated with buckwheat is a key mechanism behind weed suppression. In practice, producers should expect a dilution effect and weed suppression to be compromised when the buckwheat seeding rate is reduced in mixtures.

Effect of Fall- and Spring-Planted Cover Crops and Residual Herbicide on Emergence Dynamics of Glyphosate-Resistant Kochia (Bassia scoparia)

Abstract Two separate field experiments were conducted during the 2021-22 and 2022-23 growing seasons at Kansas State University Agricultural Research Center near Hays, KS to understand the emergence dynamics of glyphosate-resistant (GR) kochia [Bassia scoparia (L.) A. J. Scott] as influenced by fall- and spring-planted cover crops (CC) and residual herbicide. Study sites were under winter wheat (Triticum aestivum L.)-sorghum [Sorghum bicolor (L.) Moench]-fallow rotation with a natural seedbank of GR B. scoparia. In experiment 1, fall-planted CC mixture (triticale/winter peas/radish/rapeseed) was planted after wheat harvest and terminated at triticale [xTriticosecale Wittm. Ex A. Camus [Secale x Triticum] heading stage (next spring before sorghum planting). In experiment 2, spring-planted CC mixture (oats/barley/spring peas) was planted in sorghum stubbles and terminated at oats (Avena sativa L.) heading stage. Four treatments were established in each experiment: (1) nontreated control (no CC and no herbicide), (2) chemical fallow (no CC but glyphosate + acetochlor/atrazine or flumioxazin/pyroxasulfone + dicamba were used to control weeds), (3) CC terminated with glyphosate, and (4) CC terminated with glyphosate plus residual herbicide (acetochlor/atrazine for fall-planted CC and flumioxazin/pyroxasulfone for spring-planted CC). Results indicated that fall-planted CC delayed GR B. scoparia emergence by 3 to 5 weeks whereas spring-planted CC delayed emergence by 0 to 2 weeks compared to nontreated. Fall-planted CC terminated with glyphosate plus acetochlor/atrazine reduced the cumulative emergence of GR B. scoparia by 90 to 95% compared to nontreated across both yrs. Similarly, spring-planted CC terminated with glyphosate plus flumioxazin/pyroxasulfone reduced the cumulative emergence of GR B. scoparia by 83 to 90% compared to nontreated. These results suggest that fall- or spring-planted CC in combination with residual herbicide at termination can be utilized for GR B. scoparia suppression. Results from this study will help in developing prediction models for GR B. scoparia emergence under different CC strategies.

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.

394 Cover crops for efficient grazing systems

Abstract Grazing of cool-season cover crops provides a sustainable solution for extending the grazing season while potentially reducing the environmental impact of conventional row-crop farming practices. The primary objective of this study was to evaluate how different mixtures of cover crops affect stocker performance when grazed. The study was conducted across 18 paddocks that were sown with grass [‘Coker’ oat (Avena sativa)], grass + legume [‘Dixie’ crimson clover (Trifolium incarnatum)], or grass + legume + brassica [‘Turnip’ brassica (Brassica rapa subsp.; rapa)] at the Wiregrass Research and Extension Center in Headland, AL. These paddocks were randomly assigned to either grazed or un-grazed conditions (n = 3). In this study, yearling beef steers with an average body weight (BW) of 266 ± 44 kg were grazed in paddocks using the put and take method to maintain a forage allowance of 1 kg dry matter per kilogram of BW. Forage samples were collected biweekly to analyze biomass, botanical composition, and forage nutritive value. Grazing occurred from January 17 to March 22, 2023 (65 d). Steer BW were recorded at the beginning and end of the grazing season to calculate average daily gain. The data were subjected to analysis as a two-way ANOVA using Glimmix in SAS 9.4 (SAS Institute, Cary, NC), harvest date was considered a repeated measure. No treatment × grazing interaction was observed on forage yield performance [average (AVG) forage yield kg DM/ha; P = 0.460]. In addition, no difference was observed among the different cover crop mixtures (AVG forage yield kg DM/ha; P = 0.670). Grazed paddocks had a greater crude protein when compared with ungrazed paddocks (Grazed vs. Ungrazed %; P = 0. 017). However, there was no effect of cover crop mixture on crude protein (CP) concentration (AVG CP %; P = 0.670 for treatment effect). These results indicate that cool-season annual cover crops can provide sufficient forage yield and quality to support sufficient animal gains, even during the relatively short grazing season. Incorporating cover crops not only improves agricultural sustainability but can also enhance the resilience and long-term health of the agroecosystem.

Improving dual cover crop mixtures to increase shoot biomass production and weed suppression potential

IntroductionCover crop services depend on biomass production and species composition of the cover crop stand. In this study, we investigated the interactions in shoot biomass of dual cover crop mixtures and their competitiveness to suppress weeds before winter under different growing conditions.MethodsA field experiment was performed on sandy loam soil in Triesdorf, Germany, for two consecutive years. The cover crop species white mustard (Sinapis alba L.), oil radish (Raphanus sativus var. oleiformis L.), phacelia (Phacelia tanacetifolia J.), Egyptian clover (Trifolium alexandrinum L.), common vetch (Vicia sativa L.), field pea (Pisum sativum L.), and field bean (Vicia faba L.) were grown in pure stands or dual mixtures. Cover crops were sown in August, and shoot biomass was harvested at the end of the vegetation period. Cover crop shoot biomass was dried, and the share of each species and the sown test weed (Brassica napus L.) were determined.ResultsThe share of shoot biomass of a cover crop species in dual-species mixtures was closely related to its shoot biomass in its pure stand. In both years, mustard and phacelia showed similar interactions in shoot biomass production when growing with a second species. Regarding competitiveness against weeds, cruciferous species outperformed other cover crop species and could suppress weeds even if they were mixed with a less competitive partner. Weed suppression of mixtures with phacelia depended on the second component in the mixture and was more effective in a dry season. Legume species, especially Egyptian clover and common vetch could not suppress weeds in a pure stand.DiscussionOur results show that species with high weed suppression potential as single stands retain this ability in dual cover crop mixtures, regardless of the suppression potential of the second species that completes the mixture.

How Do Off-Season Cover Crops Affect Soybean Weed Communities?

Weeds compete for environmental resources, leading to reduced soybean yield. In this context, integrated weed management strategies related to cultural control with the use of cover crops are necessary. Our aim was to evaluate weed occurrence in soybean systems with different cover crops. Field studies were conducted at Júlio de Castilhos, Santa Maria, Capão do Leão, Barra do Ribeiro, and Santo Ângelo, Rio Grande do Sul, Brazil. A randomized complete block design with four replications was used. Treatments consisted of black oats (Avena strigosa Schreb.), white oats (Avena sativa L.), rye (Secale cereale L.), hairy vetch (Vicia sativa L.), forage turnip (Raphanus sativus L.), and white clover (Trifolium repens L.) in pure stands or in mixtures. The analyzed variables were relative frequency, density, abundance, and importance value index, similarity index of weeds, dry shoot mass of cover crop, and soybean yield. Cover crops containing white or black oats reduced the relative importance value index of weeds, such as Lollium multiforum, Conyza spp., and Bidens pilosa. Forage turnip, hairy vetch, and white clover showed distinct responses. Black oats and forage turnip did not differ from cover crop mixtures in terms of dry shoot mass and grain yield, being superior to fallow, white clover, and hairy vetch.

Cover cropping enhanced soil aggregation and associated carbon and nitrogen storage in semi-arid silage cropping systems

Wind and water erosion in arid and semi-arid regions significantly degraded soil, reduced soil organic carbon (SOC) storage, and exacerbated the impact of climate change on agricultural productivity. Cover cropping is one of the approaches to improve soil health and reduce climate change impacts, yet its impacts on soil aggregation and associated SOC and nitrogen (N) storage in water-limited environments are poorly understood. This study aimed to evaluate soil aggregate dynamics and aggregate-associated SOC and soil total N in irrigated silage sorghum [Sorghum bicolor L. (Moench)] − corn (Zea mays L.) rotations with various cover crop mixtures: grasses + brassicas + legumes (GBL), grasses + brassicas (GB), grasses + legumes (GL), and no cover crops (NCC). Results showed in the second year of the study that, at 0–0.1 m depth, mean weight diameter and geometric mean diameter of dry aggregates were 22–23 % and 6 % greater, respectively, with cover crops than NCC. At the same depth, cover crop treatments had 15–17 %, 15–16 %, and 13 % greater SOC in 0.25–2, 0.053–0.25, and < 0.053 mm aggregate classes, respectively, compared to NCC. Similarly, at 0–0.1 m depth, N in < 0.053 mm fraction was 8–10 % greater with cover crops than without. In the fourth year of the study, water-stable aggregates (WSA) percent did not differ among treatments, but WSA-associated SOC was 31–37 % and 12–16 % greater with cover crops at 0–0.1 and 0.1–0.2 m depths, respectively, than without. The WSA-associated N at 0–0.1 m was 21–33 % greater with cover crops than without. Despite the inconsistencies in soil aggregate stability results, cover crop-integrated silage systems showed greater SOC and N within aggregate classes and water stable aggregates. This insight is crucial for advancing sustainability in silage production systems, particularly in the context of increasing climate change and variability in erosion-prone soils of arid and semi-arid regions.

Cover crop mixtures do not assemble markedly distinct soil microbiotas as compared to monocultures in a multilocation field experiment

Cover crops are used in cropping systems to enhance ecosystem services, such as soil resilience to erosion or microbial activity. Different cover crops are selected to steer specific processes, but whether cover crop mixtures have an added value over monocultures remains debated. Here, we investigated if cover crop mixtures accumulate soil microbiotas distinct from those of monocultures, potentially leading to more varied microbially-driven soil functions. We performed a field experiment at three locations in the Netherlands, each including nine cover crop monocultures, five- and eight-species mixtures, and a fallow control. After three months, we measured cover crop biomass and profiled soil bacterial, fungal, and arbuscular mycorrhizal fungal communities via amplicon sequencing. The different crop monocultures produced similar biomass across all three locations, and mixtures had average productivity compared to monocultures. The diversity and community structure of soil microbial communities was primarily determined by the geographical location, and then by cover crop treatment at each location. Although the cover crop species affected the soil microbiome differently, cover crop mixtures did neither increase microbial diversity nor the overall community differentiation compared to monocultures. Our results suggest that mixing cover crop species does not significantly influence microbially-driven soil functions, at least in short-term crop rotations.

Clay soil amendment suppressed microbial enzymatic activities while increasing nitrogen availability in sandy soils

AbstractConservation management practices often produced positive but limited desirable outcomes in US Southeast sandy soils, likely due to their intrinsically low clay contents that constrain the soil's capacity to preserve organic carbon (C) and nutrients. In the field, we tested the effectiveness of a novel approach, that is, clay soil amendment, to improve sandy soils. In October 2017, clay‐rich soils (25% clay) were spread at 25 metric tons ha−1 and tilled onto a sandy soil (1.9% clay) in the field, which was further mixed by light tillage at 0‐ to 15‐cm depth, followed by planting winter cover crop mixtures (cereal rye, crimson clover, and winter pea). The crop rotation was cotton and corn with cover crop mixtures planted in the winter fallow season. Soils (0–15 cm) were collected in August 2021 and subjected to physio‐biochemical analyses. Clay amendment increased soil clay content to 3.4%, which improved nitrogen (N) availability by 51% but inhibited the activities of C (β‐d‐cellubiosidase [CB]; β‐xylosidase [BX]; N‐acetyl‐β‐glucosaminidase [NAG]) and N (leucine aminopeptidase [LAP]) cycling enzymes, resulting in up to 78% reduction in microbial respiration. A follow‐up kinetic study on BG and LAP enzymes suggested that clay addition can have different impacts on enzymes with diverse biological origins through distinct mechanisms. Clay addition can potentially improve sandy soils by stabilizing the organic inputs in soils. However, more research is required to understand its long‐term impacts making this approach practical.

Diversified Cover Crops and No-Till Enhanced Soil Total Nitrogen and Arbuscular Mycorrhizal Fungi Diversity: A Case Study from the Karst Area of Southwest China

The deteriorating soil health under continuous monoculture is commonly found across various cropping systems. This study evaluated the effects of different tillage practices (conventional tillage and no till) and species mixtures (legumes and grasses) on arbuscular mycorrhizal fungi (AMF) community properties, soil nutrients, and enzyme activity in a 3-year experiment. Compared with traditional tillage, the number of AMF species under no-till conditions was increased, with the Glomus group being dominant. Under different tillage conditions, TN (total N) and AN (available N) contents under no till were significantly higher than those under conventional tillage, while no significant differences among other nutrients were found. The activities of soil acid phosphatase (S-ACP), soil dehydrogenase (S-DHA), and soil sucrose (S-SC) under conventional tillage were significantly higher than those under no till, and the cover crop mixtures also had an exclusive advantage in yield. Soil organic matter (SOM) indicated a significant negative correlation with glomalin-related soil protein (GRSP). The increase in diversity associated with the AMF species community was strongly correlated with the increase in three enzyme activities, and AN was negatively correlated with all species. Tillage did not significantly change soil chemistry, except for AN, and the high concentration of AN led to a decrease in AMF species. The results of this study showed that no till was an effective measure for enriching soil micro-organism population. Additionally, soil AMF diversity was improved by cover crop mixtures, and microbial diversity was higher than that under monoculture cover crops. Different AMF groups responded differently to tillage and cover crop mixtures. Across all mixtures, the combination of hairy vetch (Vicia villosa R.) and ryegrass (Lolium perenne L.) performed the best.

Long-term cover crop monocultures and mixtures improve soil multifunctionality and shift microbial communities and functions

Long-term cover crops are an emerging approach for achieving sustainable agriculture by reducing fertilizer use and enhancing soil quality. However, soil microbial communities, multifunctionality (i.e., the ability of soil ecosystems to simultaneously provide and maintain multiple ecological functions), and their relationships in cover crops remain poorly understood, especially in cover crop mixtures. To address these issues, here, we conducted a 15-year field experiment under different cover crop deployments (one legume and one brassica grown in monoculture or in mixture) in Carya cathayensis plantations. We found that cover crops significantly increased soil microbial diversity and multifunctionality, especially in mixtures. The bacterial and fungal compositions was significantly affected by cover crops. Interestingly, some taxa may serve as potential indicator species for nutrient status (i.e., bacterial Subgroup_2, Subgroup_6 and Subgroup_17). Cover crops significantly increased beneficial microbial functions (e.g., nitrogen fixation) but decreased pathogen-related functions (e.g., pathotroph). Bacterial and fungal community assemblages under cover crops were dominated by stochastic processes. Cover crops, especially mixtures, had a higher habitat niche breadth (Bcom). In addition, cover crops have more complex and stable bacterial and fungal networks. Partial least squares path modeling further confirmed that the variations in soil multifunctionality were largely related to nutrient resources. Importantly, the relative abundance of rare microbial taxa was also highly correlated with soil multifunctionality. Overall, our study illustrates that the use of cover crops in the long term can foster soil microbial specific taxa and contribute to improved soil multifunctionality. Our study provides support for the benefits of a legume-brassica mixture over monocultures of either and a theoretical basis for exploring cover crops as an ecological management model.

Influence of cover crop residue and residual herbicide on emergence dynamics of glyphosate-resistant Palmer amaranth (Amaranthus palmeri) in grain sorghum

Abstract A field study was conducted from 2020 to 2023 at Kansas State University Agricultural Research Center near Hays, KS, to understand the emergence dynamics and periodicity of glyphosate-resistant (GR) Palmer amaranth (Amaranthus palmeri S. Watson) as influenced by cover crop (CC) residue and residual herbicide in grain sorghum [Sorghum bicolor (L.) Moench]. The study site was under a wheat (Triticum aestivum L.)–sorghum–fallow rotation with a natural seedbank of GR A. palmeri. Treatments included (1) fall-planted CC mixture [winter triticale (×Triticosecale Wittm. ex A. Camus [Secale × Triticum])/winter peas (Pisum sativum L.)/rapeseed (Brassica napus L.)/radish (Raphanus sativus L.)] after wheat harvest and terminated at triticale heading stage (next spring before sorghum planting) with glyphosate alone or (2) glyphosate plus acetochlor/atrazine, (3) chemical fallow (no CC but treated with acetochlor/atrazine and dicamba before sorghum planting), and (4) nontreated control (no CC and no herbicide). Results indicated that CC terminated with glyphosate plus acetochlor/atrazine had a delayed and reduced cumulative emergence of GR A. palmeri as compared with chemical fallow and CC terminated with glyphosate alone across all 3 yr. Compared with chemical fallow, the CC terminated with glyphosate alone and glyphosate plus acetochlor/atrazine required 66 to 643 and 105 to 1,257 more cumulative growing degree days, respectively, to achieve 90% cumulative emergence of GR A. palmeri across all 3 yr. The combined effect of CC residue with glyphosate plus acetochlor/atrazine reduced the total emergence counts of GR A. palmeri by 42% to 56% and 82% to 94% as compared with chemical fallow and nontreated control, respectively. These results suggest that fall-planted CC combined with a residual herbicide at termination can be utilized for GR A. palmeri suppression in grain sorghum.

How Do Mixed Cover Crops (White Mustard + Oats) Contribute to Labile Carbon Pools in an Organic Cropping System in Serbia?

Sustainable farming is one of the priority goals of the "4 per 1000" concept with regard to the preservation of soil fertility and carbon sequestration. This paper presents a study on the use of a mixture of cover crops of self-grown oats (Avena sativa L.) and sown white mustard (Sinapis alba L.) in organic farming under the agroecological conditions of Serbia. The main objective was to identify sensitive carbon pools (microbial carbon and nitrogen, basal respiration and a number of specific groups of soil microorganisms) in organic farming with and without cover crops. The inclusion of a mixture of white mustard and self-grown oats as a cover crop led to a significantly increased biogenity of the soil compared to a control after only a few years of investigation. The number of microorganisms, soil respiration and microbial biomass carbon were significantly higher in the cover crop treatment compared to the control soil on an organic farm in Serbia. This is the first study in Serbia to investigate the effect of self-grown oats as a cover crop. Further research will incorporate a wider range of variables and factors in order to develop a sustainable and effective site-specific system for organic crop production in Serbia.

Soil fauna diversity is enhanced by vegetation complexity and no-till planting in regenerative agroecosystems

Agricultural ecosystems are driven by the need to increase yield, due to increased food demands. Conventional, intensive practices are not sustainable as they disrupt the biodiversity in the soil which performs a range of ecosystem functions that sustain soil productivity and resilience. Conservation agriculture and crop-livestock integrated agriculture have been promoted as some of the most sustainable and biodiversity-conserving forms of agriculture. This study assesses how soil macro-and mesofauna in staple crops respond to different agricultural land uses, including conventional, integrated and conservation agriculture, and lastly, natural grassland ecosystems which were used as reference sites. We compared species richness, composition, and functional structure of soil fauna among the land uses and assessed environmental drivers of these patterns. Soil macro-and mesofauna species richness was generally lower in conventional management compared to other management practices, for overall arthropods and for the separate taxonomic groups, beetles, earthworms, spiders, and springtails. Different functional guilds varied in their responses to the farming systems. Vegetation cover and plant litter cover are the variables which benefited most fauna diversity. The practices of no-till plantings coupled with diversified crop rotations and cover crop mixtures under conservation and integrated agricultural management enhances the diversity of earthworms, collembola, beetles, and spiders. Low-disturbance soil management, crop diversification and within-crop habitat complexity preserves arthropod soil fauna diversity in staple crops.

Effects of cultural practices on weed community and seedbank dynamics in a potato rotation

ContextStagnant yields and declining soil health are common characteristics of high-intensity, low-residue cropping systems, such as potato, particularly in northeastern North America. Incorporating cultural practices including cover cropping and manure application is a way to combat declines in agroecosystem health and potato productivity. However, manure application and the use of cover crops may exacerbate weed issues through seedbank additions. ObjectiveThis study was aimed at investigating how the cultural practices of cover cropping and manure application and their associated management activities can alter weed community dynamics and weed seedbank composition in a northeastern North American potato rotation. MethodsThe study evaluated the use of eight cover crop mixtures—annual and perennial grasses and legumes—grown over two years with/without manure added in year one of the rotation. It also examined the effects of the cover crop mixtures and the presence/absence of manure on the weed community and on seedbank dynamics within a three-year potato rotation between 2019 and 2021. ResultsIn year one of the study and directly after application, manure plots had greater weed seedbank density and species richness; however, this did not result in greater in-season weed biomass. Manure application resulted in a gradual decline in weed seedbank density over time regardless of cover crop treatment. Further, manure application increased the in-season competitive ability of cover crops, resulting in greater weed suppression per unit of cover crop biomass. In contrast, in the absence of manure, weed seedbank density remained largely unchanged through time regardless of cover crop treatment. We found that management practices associated with annual and perennial cover crops had distinct ecological filtering effects throughout the rotation on the weed community and prevented the dominance of any particular species. ConclusionTogether, our results demonstrate that combining the cultural practices of annual or perennial cover cropping and manure application contributes to weed suppression and should be considered an important component of sustainable potato production.

Soil carbon and aggregate stability are positively related and increased under combined soil amendment, tillage, and cover cropping practices

AbstractAgricultural practices alter the organic carbon dynamics in soil. An experiment was conducted to study the effect of carbon amendments, tillage, and cover cropping on permanganate oxidizable carbon (POXC), total organic carbon (TOC), and wet aggregate stability (WAS) in a 2‐year crop sequence (corn–cover crop–cotton–cover crop) at the Texas A&amp;M Research Farm. Two carbon amendments (biochar and composted biosolid) were applied at the rate of 500 kg C ha−1, along with a control. Two tillage practices were evaluated: conventional tillage (CT) and no‐tillage (No‐Till). A cover crop (CC) mixture of oat, mustard, and pea and no cover crop (No‐CC) were also evaluated. Treatments were arranged in a split‐split plot design with four replications. Amending the soil with carbon as composted biosolid or biochar affected POXC at both the 0‐ to 5‐ and 5‐ to 15‐cm depths. The POXC was significantly higher for the biochar treated plots for corn and CC after corn but significantly lower POXC was observed after cotton with biochar‐treated plots. The POXC increased under No‐Till compared with CT and CC plots relative to No‐CC plots. The TOC was not sensitive to soil management practices. The POXC and TOC both decreased with depth. The WAS greater under No‐Till and CC plots. The POXC and WAS were influenced by soil management practices and can be useful indicators to assess short‐term soil health improvements. The POXC and WAS were positively related, suggesting that one may be used to predict the other.

89 Improving cattle grazing efficiency with multi-functional cover crops

Abstract Grazing cool-season cover crops provides a sustainable way of extending the grazing season and reducing the impact row-crop farming systems on the environment. Cover crops promote soil health; however, the impacts of grazing cover crops on soil health in the Southeast are not well understood. The objective of the current study was to determine the effects of different cover crop mixtures on a cotton (Gossypium hirsutum)-peanut (Arachis hypogaea) cropping system. The experiment consisted of 18 paddocks, planted in mixtures of grass [‘Coker’ oat (Avena sativa)], grass + legume [‘Dixie’ crimson clover (Trifolium incarnatum)], or grass + legume + brassica [(‘T-raptor’ brassica (Brassica napus × B. rapa)] planted at the Wiregrass Research and Extension Center (Headland, AL). Paddocks were randomly allocated to grazed or not grazed (n = 3). Grazed paddocks were grazed with yearling beef steers (266 ± 44 kg) using the put and take method to maintain a forage alloance of 1 kg DM per kg BW. Forage samples were collected every 2 wk, for biomass, botanical compositions, and nutritive value. Paddocks were grazed from 17 Jan – 22 Mar 2023 (65 d) and steer BW were taken at the beginning and end of the grazing season for calculation of average daily gain Data were analyzed using Proc Glimmix of SAS 9.4 (SAS Institute, Cary, NC) with forage sampling date considered a repeated measure. No difference in steer average daily gain was detected among grazed treatments (1.5 kg/d; P &amp;gt; 0.44). Cover crop (forage) biomass was also not different among all grazed and ungrazed treatments (1,097 kg DM/ha; P = 0.56). According to the results, grazing cool-season annual cover crops may reduce the supplementation required to maintain cattle through the winter months in the Southeast.

Reducing energy and carbon footprint in semi-arid irrigated cropping systems through crop diversification

Energy and carbon (C) footprints of agricultural production practices have garnered high attention due to rising energy costs and increasing global warming. However, the contribution of conservation and regenerative farming practices, including cover cropping, on energy and C footprints have not yet been documented for cropping systems in arid and semi-arid regions. This study evaluated the energy and C footprint of cover crop integrated silage maize (Zea mays L.) and sorghum (Sorghum bicolor L. Moench) production systems in the semi-arid region of the southwestern US. The treatments were mixtures of winter cover crops: i) grasses and legumes (GL), ii) grasses, brassicas, and legumes (GBL), iii) grasses and brassicas (GB), and iv) no cover crops (NCC) control for each crop production system. Results showed cover crops had 24.1–24.5% greater energy input than NCC. In silage maize rotation, energy output was 17–22% greater in GBL and GL than in NCC. In silage sorghum rotation, the energy output was 15–24% greater in all cover crops than in NCC. The resulting net energy was 16–21% greater in GBL and GL than in NCC under silage maize, while it was 18–24% greater in GBL and GB than in NCC under silage sorghum. In the silage maize system, the C-footprint per kg yield was not different among treatments, whereas in silage sorghum, it was 58% greater in GBL than in NCC. The benefit-to-cost ratio was greater than one for all treatments, but the additional revenue through C credit programs could make cover cropping a more feasible and beneficial approach, improving economic and environmental sustainability while producing silage crops. While the C footprint was crop rotation specific, cover cropping should be encouraged over crop-fallow systems to producers in semi-arid environments to reduce energy usage and increase C-credit benefits. Clear national and state policy on the C credit program will also enhance economic and environmental benefits by adopting cover cropping and other regenerative farming practices.

Seedcorn maggot response to planting date, cover crops, and tillage in organic cropping systems.

Seedcorn maggot, Delia platura (Meigen) (Diptera: Anthomyiidae), is an economically important early-season pest of corn and soybean in the United States. Adult seedcorn maggot is attracted to decomposing plant residues for oviposition, creating potential management issues where growers typically use tillage to incorporate fertility amendments and to create a seedbed. The use of growing degree-day models to time planting dates is an important tool for effectively managing this pest, but their use has not been examined in organic crop production. Here, we report the results of experiments to determine the effects of cover crops, tillage, and relative planting date on seedcorn maggot in corn and soybean in 2 experiments: The first during the transition to organic from conventional management and the second during the 3 yr following organic certification in central Pennsylvania, United States. Overall, delaying the planting date by 1-2 wk reduced fly emergence in corn, but not in soybean in both experiments. Seedcorn maggot emergence was also consistently greater in corn than in soybean, with 6 times more flies in corn than in soy. About 15 times more seedcorn maggot flies emerged from corn in treatments in which cover crops were managed with tillage compared to treatments in which cover crops were terminated with a roller-crimper followed by no-till planting of corn. Fly emergence was negatively related to the proportion of legumes in the cover crop mixture preceding corn. These results can help inform soil, cover crop, and crop decisions for organic growers in the Mid-Atlantic United States.