SOIL HEALTH RESEARCH IN ALABAMA ROW CROP SYSTEMS

• Sponsoring Institution: National Institute of Food and Agriculture
• Project Status: COMPLETE
• Funding Source: HATCH
• Reporting Frequency: Annual
• Accession No.: 1017954
• Project Start Date: Oct 15, 2018
• Project End Date: Oct 1, 2023
• Program Code: [(N/A)]- (N/A)

Recipient Organization
AUBURN UNIVERSITY
108 M. WHITE SMITH HALL
AUBURN,AL 36849

Performing Department
Crop, Soil and Environmental Sciences

Non Technical Summary
Many soils across Alabama have low water- and nutrient-holding capacities due to warm climate, coarse-textured soils, and intensive farming practices traditionallyused in the state. Soil conservation practices such as cover cropping and reduced tillage have potential to improve soil health, reduce erosion, and increase water-use efficiency while maintaining/increasing productivity. Researchoutlined in this proposalis targeted to increase producer knowledge of soil conservation practices. The objectives of this proposal are 1) to evaluate the effects of conservation agronomic practices (e.g., cover cropping) to improve soil health and productivity of Alabama soils and 2) to assess short-term soilhealth indicators for their ability to predict long-term improvements in soil health. Field experiments throughout Alabama have been established todetermine best strategies for cover crop management in common Alabama row crop production systems. Management considerations such as planting date, seeding rate, andvarieties willbe assesedto determinemaximize the benefits of cover crops and cover crop mixtures to improve soil health. In addition, indicators of soil health, including total C, mineralizable soil N, soil microbial biomass C, active C, soil penetrability, and aggregate stability will be measured over time in various field experiments toassess their ability to predict long-term improvements in soil health. An anticipated outcome of this research is improved productivity and sustainability of row crop production systems.

Animal Health Component

100%

Research Effort Categories

Basic

(N/A)

Applied

100%

Developmental

(N/A)

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
205	0199	1060	100%

Knowledge Area
205 - Plant Management Systems;

Subject Of Investigation
0199 - Soil and land, general;

Field Of Science
1060 - Biology (whole systems);

Keywords

soil health

cover crop

row crop

Goals / Objectives
Objective 1: Evaluate the effects of conservation agronomic practices (e.g., cover cropping) to improve soil health and productivity of Alabama soils.Many soils in Alabama, as well as across the Southeast, have low water- and nutrient-holding capacities and are depleted in soil organic matter (SOM) due to warm climate, coarse-textured soils, and susceptibility to erosion. As demand for food increases under a changing climate, methods for sustainable crop production must be identified to supply global demand. Cover crops and conservation tillage are important pieces of conservation systems which can improve soil health and reduce nutrient runoff. The most common conservation systems in Alabama incorporate small grains, such as cereal rye, as winter cover crops into row-crop rotations. However, Alabama producers are gaining interest in cover crop mixtures to maximize benefits to the soil, since different cover crop species can have distinct benefits to the soil. For example, deep-rooted brassica cover crops (e.g., "tillage" radish) may have potential to alleviate soil compaction in row crop production systems. Legume cover crops (e.g., crimson clover) can supplement nitrogen to other cover crops in a mixture and/or to subsequent cash crops. Information on the benefits of cover crops and cover crop mixtures to improved soil health is needed for Alabama row crop producers to adopt these practices. In addition, basic information on cover crop management, such as appropriate seeding rates and varieties, is needed for producers to determine which cover crop monocultures or mixtures are feasible in their production systems.Objective 2: Assess short-term soil health indicators for their ability to predict long-term improvements in soil health.Soil health is described as the continued capacity of soil to perform functions which support life on earth. These functions include supporting plants to provide food and fiber, filtering water, providing habitat for living organisms, sequestering carbon, and many others. Soil health indicator tests are used to measure soil chemical, physical, and biological properties which impact soil functions. Soil organic matter is a universally-accepted indicator of soil health because of its role in increasing soil nutrient- and water-holding capacities as well as improving soil aggregation and soil structure. However, it can take several years of management with conservation practices to observe increases in SOM concentration, particularly in highly-weathered Ultisols of the southeastern United States. There is national interest in identifying early indicators of soil health which predict improvements in soil chemical, physical, and biological health following short-term conservation management. Potential short-term indicators of soil health may include active carbon fractions, aggregate stability, penetration resistance, and nitrogen mineralization. Research is needed to determine the best methods for assessing short-term improvements in soil health in highly-weathered Ultisols of the Southeast.

Project Methods
Site DescriptionsField experiments for objectives 1 and 2 will be conducted at Alabama Agricultural Experiment Stations (AAES) throughout Alabama, including: E.V Smith Research Center (EVS), Tennessee Valley Research and Extension Center (TVREC), and Wiregrass Research and Extension Center (WREC). Treatments will evaluate various cover crops monocultures and mixtures (e.g., cereal rye, crimson clover, and tillage radish) for their ability to improve soil health in cotton-peanut and cotton-soybean rotations. Some experiments will contain cover crops monocultures and mixtures at varying seeding rates to determine optimal seeding rates to maximize cover crop biomass. Some experiments will contain treatments with grazing to assess impact of cattle grazing of cover crops in row-crops systems. Winter cover crop treatments will be replicated at least four times in randomized complete block design at various locations in dryland and irrigated scenarios. Summer cash crops will vary according to location but will include cotton, peanut, and soybean. Experiments containing monocultures and mixtures cover crops will be evaluated in dryland and irrigated scenarios to assess their impact on soil health in various production scenarios.Assessment of Cover Crop and Cash Crop Productivity Identifying cover crops which produce high biomass is essential to gain many associated benefits, including moisture retention, weed suppression, and organic matter storage. Cover crop biomass will be determined according to treatment from various field experiments by collecting biomass from a 0.25 m2 area. Biomass samples will be weighed and oven-dried at 60°C to determine dry matter biomass. Additional residue samples will be placed in decomposition bags and collected at various stages of decomposition determine how quickly various covers degrade. Total N content at varying decomposition stages will also be measured from samples at varying decomposition stages to assess N release throughout the cash crop growing season. Differences in cover crop biomass, cover crop residue decomposition rates, N release from residue, and summer crop (i.e. cotton, soybean, peanut) yield will be evaluated each year according to cover crops treatment to evaluate the effect of cover crops on productivity.Laboratory and Field Analyses for Soil Health AssessmentIndicators of soil health, including total C, mineralizable soil N, soil microbial biomass C, active C, and soil penetrability, will be measured according to treatment pre- and post-crop cover crop incorporation for various experiments on research stations and on-farm trials. Soil samples will be collected using a truck-mounted Giddings® probe from depth intervals of 0-5, 5-10, 10-15, and 15-30 cm. Total organic carbon will be measured according to treatment via dry combustion with a CN LECO 2000 analyzer (LECO Corp., St. Joseph, MI). Soil aggregate stability, soil microbial biomass, active C (Weil et al., 2003), and Mehlich1-extractable nutrients will be measured each year for three years two weeks after cover crop termination. Soil penetration resistance will be measured in situ at the beginning of the study and each year following cover crop termination. Laboratory incubation studies will be used to determine potential soil C decomposition and N mineralization each year after termination of winter cover crops.Dissemination of ResultsResults from these projects will be transferred to producers in the form of: 1) presentations at producer workshops and field days on soil fertility and soil conservation practices (including topics such as cover crop selection, cover crop management, and improved fertility management), 2) production and distribution of materials in the form of timely information, extension publications, mass media articles, and peer-reviewed journal articles related to soil fertility and soil health, and 3) production of videos for the "Alabama Soil Health" website and "Alabama Crops" Facebook page to provide producers with up-to-date results from these studies.

Progress 10/01/20 to 09/30/21

Outputs
Target Audience:Alabama farmers, the Alabama Cooperative Extension System; Alabama NRCS, Alabama Soil and Water Conservation Society, Alabama Crop Consultants, farmers in neighboring states of Georgia and Florida; members of the Alabama Crop Management Association, Alabama Cotton Commission; and the American Society of Agronomy-Crop Science Society of America-Soil Scinece Society of America tri-socieites. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?Five graduate students have completed MS degrees related to the current Hatch project from 2017-2021. An additional graduate student has recently begun working on research to evaluate soil health in southeastern row crop production systems under various grazing systems. All graduate students as well as several undergraduate students have been trained in each of the following areas: soil and plant sample collection, lab analyses, data management, data analysis, and analytical writing. In addition, three graduate students and one undergraduate student presented results at regional and national meetings and producer field days in 2021. How have the results been disseminated to communities of interest?Results have been disseminated to scientific communities through presentations at regional and national meetings. Four abstracts were presented at the 2021ASA-CSSA-SSSA conference in Slat Lake City, UT; oneabstractwaspresented at the 2021American Society of Agronomy Southern Branch meeting (virtual). Threeecover crop field days wereorganized by the PI in 2021. . Results have also been presented by the PI at numerous county and state-wide production meetings (both in-person and virtually) to present results to producers, USDA-NRCS employees, Extension employees, and industry personnel in Alabama. What do you plan to do during the next reporting period to accomplish the goals?Field trials will continue to evaluate the effect of cover crops on soil health throughout the state. One continuing experiment contains treatments to compare the impact of cover crops monocultures and mixtures on total soil C,active C, aggregate stability, soil penetrability, and cash crop yield; this study has three locations throughout the state of Alabama, so that production systems in varying climates and soil types can be compared. Another continuing experiment will be to assess impact of various cattle grazing strategies on soil health in row crop production systems which incorporate winter grazing. Five on-farm demonstration projects were initiated in 2021to evaluate the effect cover crop specieson soil health and biomass production on Alabama farms.

Impacts
What was accomplished under these goals? Studies were established in 2017 in the Tennessee Valley (TVREC) and Wiregrass (WREC) regions of Alabama to examine the impact of cover crops on dynamic soil health indicators. Treatments including fallow, along with monocultures and combinations of cereal rye (Secale cereale), crimson clover (Trifolium incarnatum), and Daikon radish (Raphanus sativus) were arranged in a randomized complete block design in cotton-legume cash crop rotations. Soil health indicators measured from 2017-2021include cover crop biomass permanganate oxidizable carbon (POXC), soilorganic carbon (SOC), water stable aggregates (WSA), and soil strength (AUCC.I.).Cover crop biomass was variable from year to year and was dependent on planting date and weather conditions. In the Coastal Plain, treatments containing clover had on average 44% higher above ground biomass than those that did not have clover. At the northern Tennessee Valley location, the rye treatments performed slightly better than clover, but both rye and clover had much higher biomass than radish. In one site-year, a two-species mixture produced more biomass than both of its monoculture constituents. In the top 5 cm of soil, all cover crops with the exception of the radish monoculture increased SOC by 23% compared to the winter fallow treatment. In the 5-10 cm depths, rye-radish and rye-clover mixes increased SOC by 17% compared to the fallow. Similarly, some cover crop treatments were able to increase POXC compared to the fallow control. In the Coastal Plain, cover crop treatments had little effect on SOC and POXC due to the coarse and low organic matter soil type. In Tennessee Valley, the soil is finer-textured and can retain more soil organic matter than the coarser-textured Coastal Plain soil. Soil organic C and POXC were both highly correlated, and both of these indicators may be useful for determining the effects of cover cropping in some soil types. Aggregate stability did not show many meaningful differences at either location. Soil strength was highly variable with season, but it was affected four out of the eight site-years of this study. Treatments containing rye or clover decreased soil strength in the Tennessee Valley by 19% after four years of cover crop utilization. Differences in soil strength were also observed in the Coastal Plain, but they were inconsistent. In the Tennessee Valley, the rye monoculture and each 2-species mixture were able to increase cotton yield 25% compared to the no cover crop control. Conversely, there were no cover crop 5 treatments that were able to increase cash crop yield in the Coastal Plain. Utilization of cover crops shows the potential to improve soil health and reverse the effects of soil degradation depending on the soil type and the cover crops used.

Publications

• Type: Conference Papers and Presentations Status: Accepted Year Published: 2021 Citation: Decker, H., A.V. Gamble, and Y. Feng. 2021. Soil microbial properties after 100+ years of soil fertility management and cover crops. 2021 American Society of Agronomy International Meeting, Salt Lake City, UT.
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2021 Citation: Decker, H., A. Johnson, A.V. Gamble, and K. Balkcom. 2021. Soil health assessment of monocultures and mixes in the Southeast U.S. 2021 American Society of Agronomy International Meeting, Salt Lake City, UT.
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2021 Citation: Akins, J., A.V. Gamble, A. Jacobson, and K. Balkcom. 2021. Cover crop effects on insect dynamics in cropping systems of the Southeast. 2021 American Society of Agronomy International Meeting, Salt Lake City, UT.
• Type: Journal Articles Status: Published Year Published: 2021 Citation: Johnson, A.M., Gamble, A.V., K.S. Balkcom, and N.R. Hull. 2021. Influence of Cover Crop Mixtures on Soil Health in Southeastern Crop Production Systems. Agrosystems, Geosciences & Environment. 4(3) doi.org/10.1002/agg2.20202
• Type: Theses/Dissertations Status: Accepted Year Published: 2021 Citation: Decker, H. 2021. Influence of Cover Crops and Fertility Management on Soil Health and Soil Microbial Community [Master's thesis]. Auburn University. Auburn, AL.
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2021 Citation: Johnson, A. and A.V. Gamble. 2021. Changes in macronutrient concentrations following four years of cover crop implementation. 2021 American Society of Agronomy International Meeting, Salt Lake City, UT.

Progress 10/01/19 to 09/30/20

Outputs
Target Audience:Alabama row crop producers, Alabama crop consultants, Alabama NRCS, Alabama Soil and Water Conservation Districts Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?Three graduate students have completed MS degrees related to the current Hatch project in 2020. An additional graduate student has recently begun working on research to evaluate soil health in southeastern row crop production systems under various cover crop treatments.All graduate students as well as several undergraduate students have been trained in each of the following areas: soil and plant sample collection, lab analyses, data management, data analysis, and analytical writing. In addition, allgraduate students and presented results at regional and national meetings and producer field days in 2020. How have the results been disseminated to communities of interest?Results have been disseminated to scientific communities through presentations at regional and national meetings. Three abstracts were presented at the 2020ASA-CSSA-SSSA virtual conference; two abstracts were presented at the 2020American Society of Agronomy Southern Branch meeting in Louisville, KY. Onecover crop field day was organized by the PI inNorth Alabama in February 2020. Other planned cover crop field days were cancelled due to COVID restrictions. Results have alsobeen presented by the PI at numerous county and state-wide production meetings (both in-person and virtually) to present results to producers, USDA-NRCS employees, Extension employees, and industry personnel in Alabama. What do you plan to do during the next reporting period to accomplish the goals?Field trials will continue to evaluate the effect of cover crops on soil health throughout the state.One continuing experiment contains treatments to compare the impact of cover crops monocultures and mixtures on total soil C, mineralizable soil N, soil microbial biomass C, active C, aggregate stability soil penetrability, and cash crop yield; this study has three locations throughout the state of Alabama, so that production systems in varying climates and soil types can be compared. Another continuing experiment will be to assess impact of various cattle grazing strategies on soil health in row crop production systems which incorporate winter grazing. Another on-farm experiment will be initiated to evaluate cover crop incorporation effects on soil health, nutrient runoff, and cash crop yield on three Alabama farms.

Impacts
What was accomplished under these goals? Studies were established in 2017 in the Tennessee Valley (TVREC) and Wiregrass (WREC) regions of Alabama to examine the impact of cover crops on dynamic soil health indicators. Treatments including fallow, along with monocultures and combinations of cereal rye (Secale cereale), crimson clover (Trifolium incarnatum), and Daikon radish (Raphanus sativus) were arranged in a randomized complete block design in cotton-legume cash crop rotations. Soil health indicators measured from 2017-2020 includepermanganate oxidizable carbon (POXC), total carbon (TC), water stable aggregates (WSA), and soil strength (AUCC.I.). Cover crops did not increase WSA compared to fallow after two years of treatment. At TVREC, POXC in the 10-15 cm depth increased 60.6% under crimson clover compared to fallow. At TVREC, TC increased following two years of crimson clover, rye-clover, and rye-radish compared to fallow by 14.3, 11.6, and 15.2%, respectively, across the 0-15 cm depth. No differences in AUCC.I. occurred between treatments in 2018 at either location. In 2019, AUCC.I. at TVREC was higher under fallow and radish treatments compared to rye and rye-radish, while AUCC.I. at WREC in 2019 was higher under clover-containing treatments compared to fallow and rye. Overall, some improvements in soil health indicators were observed following two years of cover crop utilization, but long-term cover crop use may be necessary to observe more consistent soil health changes. A study was established in the Wiregrass region of AL to determine the effects of an ICL system in which winter grazing livestock were incorporated into a cotton-peanut rotation with a winter cover crop mixture of 'Cosaque' oats, 'FL401' rye, 'Sunrise' crimson clover, and 'T-raptor' brassica. Three cattle removal dates (i.e., mid- February, mid-March, mid-April) and an ungrazed control were compared to assess the effect of grazing period length on soil organic carbon (SOC), permanganate oxidizable carbon (POXC), water stable aggregates (WSA), penetration resistance (PR), microbial biomass-carbon (MBC), and arbuscular mycorrhizal fungi (AMF) colonization rates. After the first two years of integrating winter grazing, selected soil health indicators did not change based upon length of grazing. The ungrazed control and treatments with shorter grazing periods resulted in increased biomass on the soil surface at the time of cover crop termination. Microbial biomass C was the only soil health indicator to exhibit a treatment effect having greater MBC in the ungrazed control treatments, likely due to greater cover crop biomass present on the soil surface at termination. Water stable aggregates and PR were unaffected by the presence of livestock and length of grazing showing that negative physical impacts of winter grazing are not detectable in the early years of this study. Higher biomass may have increased cotton lint yield in 2019, possibly through conserving soil moisture during the cash crop growing season. However, peanut yield in 2020 was unaffected by presence of livestock or grazing time. The lack of consistent results may indicate that integrating winter grazing livestock does not negatively nor positively impact soil health in southeastern row crop production systems. However, more time under this management will be needed to thoroughly evaluate how winter grazing livestock impact soil health and yield.

Publications

• Type: Conference Papers and Presentations Status: Published Year Published: 2020 Citation: Crowell, H., A.V. Gamble, Y. Feng, and K.S. Balkcom. 2020. Impact of Winter Cover Crop Grazing on Soil Health in Southeastern Cropping Systems. 2020 American Society of Agronomy Southern Branch Meeting, Lexington, KY.
• Type: Conference Papers and Presentations Status: Published Year Published: 2020 Citation: Akins, J., A. Jacobson, and A.V. Gamble. 2020. Evaluation of Insect Dynamics in Southeastern Cover Cropping Systems. 2020 American Society of Agronomy Southern Branch Meeting, Lexington, KY. (This poster won 2nd place in the Graduate Student Poster Competition)
• Type: Conference Papers and Presentations Status: Published Year Published: 2020 Citation: 2 Crowell, H., A.V. Gamble, Y. Feng, and K.S. Balkcom. 2020. Grazing Cover Crops: Effects of Cattle Removal Date on Animal and Cover Crop Performance. 2020 American Society of Agronomy International Meeting. (virtual)
• Type: Theses/Dissertations Status: Published Year Published: 2020 Citation: Johnson, Anna. 2020. Influence of Cover Crop Mixtures on Soil Health and Weed Control in Cotton Production Systems. Master's thesis. Auburn University, Auburn, AL.
• Type: Theses/Dissertations Status: Published Year Published: 2020 Citation: Crowell, Hayley. 2020. Impacts of Winter Grazing on Soil Health in Southeastern Cropping Systems. Master's thesis. Auburn University, Auburn, AL.
• Type: Theses/Dissertations Status: Published Year Published: 2020 Citation: Akins, Joey. 2020. Cover Crop Effects on Insect Dynamics in Cropping Systems of the Southeastern U.S. Master's thesis. Auburn University, Auburn, AL.
• Type: Conference Papers and Presentations Status: Published Year Published: 2020 Citation: Johnson, A., K.S. Balkcom, and A.V. Gamble. 2020. Evaluation of Soil Health Under Cover Crop Mixtures in Southeastern Row Crop Production Systems. 2020 American Society of Agronomy International Meeting. (virtual)

Progress 10/15/18 to 09/30/19

Outputs
Target Audience:Alabama farmers,the Alabama Cooperative Extension System; Alabama NRCS, Alabama Soil and Water Conservation Society, Alabama Crop Consultants, farmers in neighboring states ofGeorgia and Florida; members of the Alabama Crop Management Association, Alabama Cotton Commission; and the American Society of Agronomy-Crop Science Society of America-Soil Scinece Society of America tri-socieites. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?Four graduate students and seven undergraduate students have been trained under the current project. Graduate students have been trained in each of the following areas: soil and plant sample collection, lab analyses, data management, data analysis, and analytical writing. In addition, all four graduate students and one undergraduate presented results at regional and national meetings. How have the results been disseminated to communities of interest?Results have been disseminated to scientific communities through presentations at regional and national meetings. Five abstracts were presented at the 2019 ASA-CSSA-SSSA conference in San Antonio, TX; three abstracts were presented at the 2019 Southern Cover Crop Conference in Auburn, AL; one abstract was presented at the 2019 Southern American Society of Agronomy meeting in Birmingham, AL. Two cover crop field days were organized by the PI, one in Southeast Alabama and one in central Alabama to disseminate results to producers, USDA-NRCS employees, Extension employees, and industry personnel in Alabama. In addition, the PI was co-organizer of the 2019 Southern Cover Crop Conference, which took place in Auburn, AL. Results from this study and other relevant research from the Southeast was presented at this conference. Results have also been presented to producers and other agricultural professionalsat the 2019 Alabama Certified Crop Advisor Training, the 2019 Alabama Crop Management Assicoation Meeting, the 2019 Alabama Soil and Water Conservation Society Annual Meeting, the 2019 Southwest Alabama and Northwest Florida Row Crops Expo, and other county and regional production meetings in Alabama. What do you plan to do during the next reporting period to accomplish the goals?Field trials will continue to evaluate the effect of cover crops on soil health throughout the state. at varying seeding rates to determine optimal seeding rates to maximize cover crop biomass. One continuing experiment contains treatments to compare the impact of cover crops monocultures and mixtures on total soil C, mineralizable soil N, soil microbial biomass C, active C, aggregate stability soil penetrability, and cash crop yield; this study has three locations throughout the state of Alabama so that production systems in varying climates and soil types can be compared. Another continuing experiment will to assess impact of various cattle grazing strategies on soil health in row crop production systems which incorporate winter grazing. Another continuing experiment will evaluate varieties and seeding rates of legume and small grain cover crop on biomass production; this experiment is part of a multi-state trial to provide producers with information on best management practices to maximize benefits of cover crops.

Impacts
What was accomplished under these goals? Restoration of soil health is vital to sustain productivity in Alabama row-crop systems. As demand for food increases, methods to improve soil health and water-use efficiency while increasing crop productivity must be identified. Cover crops have potential to improve soil health by increasing soil organic matter content, improving water-infiltration, and reducing nutrient runoff. Small grain cover crops are ideal for producing biomass which can eventually contribute organic matter to the soil. Legume cover crops can supplement nitrogen to other cover crops in a mixture and/or to subsequent cash crops. Deep-rooted brassica cover crops (e.g., "tillage" radish) may have potential to alleviate soil compaction in row crop production systems. Studies havebeen established during 2018 and 2019cash crop growing seasons to evaluate the impact of cover crops on soil health and production. Few differences have been detected in soil health measurements after two years of cover crop incorporation into crop rotations. However, it can take several years to observe differences in many soil health indicators following cover crop incorporation, especially in the warm humid climate of the southeastern United States. Additional years under these cover crop treatments will likely be required to detect changes in soil health. Cover crops did impact yields for cash crops like cotton, soybean, and peanut.Rye and Rye-Clover-Radish cover crops demonstrated the ability to increase cotton yield by up to 400 pounds of lint per acre, partitallydue to increased soil moisture retention when cotton was planted into cover crop residue. Based on average 2019 average cotton price in Alabama, these yield increasesmay result in an additional $280 per acre for cotton. Studies were established at the Tennessee Valley Research and Extension Center (TVREC), the E.V. Smith Research Center (EVS), and Wiregrass Research and Extension Center (WREC) to examine the impact of winter cover crop monocultures and mixtures on dynamic soil health indicators in cotton production systems. Eight treatments including monocultures and combinations of cereal rye (Secale cereal), crimson clover (Trifolium incarnatum), and Daikon radish (Raphanus sativus) were arranged in a randomized complete block design with winter fallow controls. Cotton was planted in the 2018 growing season at each location, peanut was planted in 2019 at WREC, and soybean was planted in 2019 at EVS and TVREC.Cover crop biomass was collected at termination, and soil samples were collected two weeks following termination. Measured soil health indicators included permanganate oxidizable carbon (POXC), total carbon (TC), water stable aggregates (WSA), and soil strength (AUCC.I.). Stratification of TC with depth occurred at TVREC, and TC under crimson clover, rye-clover, and rye-radish was higher than TC under the winter fallow control. In both 2018 and 2019, POXC at TVREC was not different between treatments at the 0-5 cm and 5-10 cm depths, while POXC was higher under crimson clover compared to the rye-crimson clover mixture at 10-15 cm. There were no differences in TC and POXC between treatments at WREC, but POXC was higher in 2019 than in 2018. WSA values from both locations were not different between treatments within the same depth class in both 2018 and 2019. No differences in AUCC.I.) occurred between treatments at TVREC, while the rye monoculture was less compacted than the crimson clover monoculture and crimson clover/radish mixture at WREC. Additional years under these cover crop treatments may be required to detect changes in soil health.At EVS, cover crop influenced cotton yield. When examining effect of cover crops on cash crop yields, the rye and rye-clover-radish mixture treatments increased cotton lint yield compared to the fallow treatment. The fallow treatment yield averaged approximately 1270 lbs lint per acre, while the rye and rye-clover-radish mixture treatment yields averaged approximately 1630 lbs lint per acre.At TVREC,cover crop also influenced cotton yield. However, no cover crop treatment had significantly different yield compared to the fallow treatment. However, the rye-radish treatment had higher yields than the clover and the clover-radish treatments. Yields for clover and clover-radish treatments averaged 1500 and 1540 lbs lint per acre, respectively, and yield for the rye-radish treatment averaged approximately 1800 lbs lint per acre. No yield data was collected at WREC in 2018 due to destruction of the crop by Hurricane Michael. In 2019, peanut yield decreased by up to 1000 lbs per acre following Clover, Clover-Radish, and Clover-Rye-Radish treatments. These results demonstrate that legume cover crops should not be planted prior to peanuts, as they may decrease peanut yield. This is likely due to increased disease incidence and reduced nodulation in a legume-legume rotation.

Publications

• Type: Theses/Dissertations Status: Published Year Published: 2019 Citation: Cofer, T. Radish Cover Crop Growth and Compaction Alleviation Potential in Southeastern Coastal Plain Soils. Auburn University, Auburn, AL.
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2019 Citation: Hull, N.*, K.S. Balkcom, T. Knappenberger, and A.V. Gamble. 2019. Cover Crop Grazing Effects on Soil Health in a Cotton and Peanut Rotation. 2019 American Society of Agronomy International Meeting, San Antonio, TX.
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2019 Citation: Johnson, A.*, K.S. Balkcom, and A.V. Gamble. 2019. Evaluation of Cover Crop Mixtures for Improving Soil Health in Ultisols. 2019 American Society of Agronomy International Meeting, San Antonio, TX.
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2019 Citation: Akins, J.*, A. Jacobson, and A.V. Gamble. 2019. Cover Crop Effects on Insect Dynamics in Cropping Systems of the Southeastern U.S. 2019 American Society of Agronomy International Meeting, San Antonio, TX.
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2019 Citation: Williford, S. J.*, N. Hull, and A.V. Gamble. 2019. Effect of Cover Crop Grazing on Soil Physical Properties. 2019 American Society of Agronomy International Meeting, San Antonio, TX.
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2019 Citation: Cofer, T.* and A.V. Gamble. 2019. Radish Cover Crop Growth and Compaction Alleviation: Effects of Cultivar and Planting Date. 2019 American Society of Agronomy International Meeting, San Antonio, TX.