Location: Genetics and Sustainable Agriculture Research
2020 Annual Report
Objectives
Objective 1. Develop more sustainable long-term soil health management systems for improved yields from humid, Southeast Agroecosystems.
Sub-objective 1.1. Increase row crop yields in the upland soils of the South and Southeast by agronomic practices that improve soil physical and biological properties including application of organic- and inorganic-amendments and planting cover crops.
Sub-objective 1.2. Develop soil water management strategies to increase the capture and storage of rain water in soil, minimize yield-robbing drought effects, and increase dryland and irrigated crop production in the South and Southeast.
Sub-objective 1.3. Determine the environmental impact in soil, water, and air of proposed novel agronomic approaches on antibiotic resistance, emissions, and nutrient risks.
Objective 2. Develop improved decision support tools and technologies based on GxExM to optimize water use efficiency of rainfall and irrigation water for better yields from humid, Southeast Agroecosystems.
Sub-objective 2.1. Develop techniques that utilize and integrate high resolution row crop canopy spectral images gathered during the growing season for in-season water management in cropping systems and fields characterized by high soil variability.
Sub-objective 2.2. Implement databases, modeling tools, and decision-making paradigms for optimizing water management and crop yield.
Approach
Several multi-year field plots will be established. These include a) cover crops for the major row cropping systems in then the southeast, b) planting various configurations of mixed cover crop species, c) cropping systems for land leveled fields, d) stabilizing dryland soybean production using cover crops and poultry litter, e) deep rooted cover crops and soil amendments and, f) cover crops and water use efficiency. From these field experiments we will measure effects on environmental quality, greenhouse gas emissions, and economics of each of the systems; environmental quality and antimicrobial resistance in each of the systems; contribution of soil organic matter to plant available water content in each of the systems; we will optimize yield by managing field variability, we will utilize high resolution thermal imaging to optimize irrigation management and we will model soil water requirements in each of the systems.
Progress Report
Sub objective 1.1. A field study has been identified to test whether integration of diverse winter cover crop with fall-applied poultry litter balancing nitrogen supply and crop demand to optimize yield, profit, and environmental protection. Cool season cover crops include winter peas, cereal rye and daikon radish were planted separately after fall-applied poultry litter at Plant Science Center. Background soil samples for biological measurements were collected in fall 2019, followed by samples collected during the cover crop season. Water activity was measured for samples collected during the cover crop season. One treatment to mimic current accepted practice was also included. Suction cup lysimeters were installed and leachate water samples collected after each rain event. Before cover crop termination, aboveground biomass was collected, and dry matter yield recorded. After termination of cover crops, soil samples were collected and analyzed for pre-planting available soil N for cash crops. Cotton and corn were planted at both locations. Litter bags from cover crop biomass were used for in situ incubation, collected frequently and mass reduction was recorded during corn and cotton growing seasons. Samples were collected for soil biological measurements at the root zone and below litter bags, including enzymatic analysis, Deoxyribose Nucleic Acid (DNA), and archived for future measurements such as metagenomics. Cotton and corn performance indicators include crop canopy height, vegetation water content, leaf area index, and leaf chlorophyll, leaf N content, total aboveground biomass and yield data were recorded. Emission [soil carbon dioxide (CO2) flux via LiCor (this is not an abbreviation) survey chamber] measurements were taken every 3 weeks to coincide with litter bag collection as well as soil nutrient and biological evaluations. The cereal rye or winter pea cover crop provided excellent early control of pigweed with the best control provided by winter pea. A high early season population of pigweed was observed in the daikon radish plots and the no cover crop plots.
A new grain drill that enables the planting of multiple cover crop species on the same pass was designed, built by ALMACO, tested, and used to plant two cover crop species in row configurations as planned. Background soil samples were collected, and poultry litter applied before planting the cover crops. After maximum cover crop growth and before applying burn-down chemicals in preparation to plant cotton, aboveground cover crop samples were collected, separated by species, and placed in a drier to determine the cover crop biomass. Soil biological and nutrients samples were collected during the middle and end of the growing season.
Sub objective 1.2. A field study has been identified in an eroded upland soil to test if integration of cover crop mixes with animal and industrial byproduct improve soil physical and hydrological properties and stabilize crop yield. Cool season deep-rooted multispecies mixed cover crop including winter wheat, crimson clover and daikon radish were planted mixed after harvesting corn in Pontotoc experiment station in the fall 2019. After planting corn, inorganic fertilizer N, soil amendment including poultry litter with/without FGD gypsum and lignite were applied. Litter bags were placed in field to determine cover crop residue decomposition. Before cover crop termination, aboveground biomass was collected, and dry matter yield recorded. A total of five litter bags were left in the plots and were collected every three weeks during the corn growing season. Soil samples were collected beneath each litter bag to analyze for total inorganic N concentration as the function of residue decomposition. Suction pen lysimeters were deployed vertically into experimental plots to monitor leachate volume as an indicator of soil infiltration and soil water storage following rain events. Sensors were deployed to monitor ambient environmental conditions. Corn growth parameters and grain yield were recorded. Soil physical and hydrological properties were evaluated. Soil enzyme and genomic DNA was collected, and cores initially screened for Deoxyribose Ncleic Acid based gene indicators and microplate analysis of enzymes have been conducted. Emission (soil carbon dioxide (CO2) flux via LiCor survey chamber) measurements have been taken every 3 weeks to coincide with litter bag collection as well as soil nutrient and biological evaluations.
The field experiment at MSU Pontotoc Experiment Station in Pontotoc County was conducted. In the fall of 2019, five different cover crop species were planted with three different fertilizer treatments. The five cover crops consisted of: wheat, cereal rye, vetch, mustard/cereal rye, and native vegetation. The three fertilizer treatments were poultry litter, standard pelletized fertilizer, and no fertilizer. We sampled 45 of the 60 plots to measure initial conditions of soil physical properties, soil moisture and nutrients before the spring planting of the soybeans. We also installed soil matric potential sensors in the wheat treatment plots and native plots. The sensors included watermark sensors of Irrometer Inc. and time domain reflectometry (tdr) sensors from Acclima Inc. We also have canopy temperature sensors in these treatments to measure the effects of crop water stress throughout the 2020 growing season. Cover crop dry biomass was measured after cover crop kill.
Sub objective 1.3. Samples were analyzed for antibiotic resistance gene presence from all experimental samples. Sub samples were archived for further analysis using Deoxyribose Nucleic Acid and RiboNucleic Acid based approaches. Samples were collected from high throughput screening of antimicrobial resistance genes. Antibiotic resistance genes were analyzed from extracted Deoxyribose Nucleic Acid (DNA). Based on initial results, it was deemed not necessary for use of cultivation assays for pathogenic bacteria.
Sub objective 2.1. An existing field that was planted with soybean in the previous three years was modified to study whether poultry litter would alleviate Mn toxicity in cotton. Plots were split into two subplots in which one half received recommended lime, while the other did not receive lime. The plots were fertilized with poultry litter, with recommended synthetic N and other fertilizers, or left unfertilized. All fertilizer applications were carried according to plan. Leaf samples were collected and analyzed for nutrients. Cotton yield and plant growth data were collected according to plan. Preliminary results show that liming an acidic soil reduces cotton leaf manganese levels regardless of whether the cotton was unfertilized or fertilized with poultry litter or normal synthetic fertilizers. But this reduction in tissue manganese content did not lead to improved cotton yield. Fertilizing with poultry litter, however, increased cotton yield suggesting that poultry litter may counter the detrimental effect of low pH soils.
Sub objective 2.2. Sample data was collected for all relevant experimental sites (A-F, J, K). Data were input into GOSSYM and compiled in SSURGO from across Mississippi sample sites. Weather and soil database data were incorporated into RZWQM2 and determined how much and under what condition cover crop would have benefits.
Accomplishments
1. Flooded rice fields improve soil biology. Because rice is a staple of food around the world, a large amount of land is required for production and agricultural sustainability is necessary to further protect the environment and maintain productivity. The current study investigated sustainable rice production using annual flooding to create waterfowl habitat as a benefit to soil quality compared with conventional production systems. Flooding occurs in winter, thus allowing for waterfowl to establish habitats, depositing fecal matter as well as further the breakdown of rice stubble. ARS researchers at Mississippi State, Mississippi, in conjunction with university researchers determined that this system is potentially sustainable, at least on a short-term basis, based on soil health parameters such as soil biology and nutrients. The team measured soil biological activity, microbial group members, and plant nutrient levels. Overall, flooded fields with greater waterfowl activity had higher levels of soil nutrients and biological activity. Some microbial groups indicated that fecal depositions were greater in flooded fields, while bird monitoring stations also indicated flooded fields had increased bird activity. Results indicated as much as a 33% less nitrogen fertilization would be needed for rice production and a potential doubling of soil organic matter when fields are flooded in winter and used by waterfowl.
2. Pelleted biosolid benefits row crop growers. Land application of animal and industrial by-products with high organic matter content helps to establish optimal soil fertility conditions for crop growth and development and potentially reduces the need for synthetic fertilizers. Consequently, this practice contributes to reduced nutrient levels found in surface water. Information on soil and crop responses to pelleted biosolids under different cropping systems will benefit growers who are using this alternative fertilizer. ARS researchers in Mississippi State, Mississippi, evaluated the long-term impacts of pelleted biosolids on corn, soybean and cotton yield and Nitrogen utilization. No difference in corn grain yield and cotton lint yield were obtained between pelleted biosolid and inorganic fertilizer Nitrogen at equivalent plant available Nitrogen rate. This indicated that pelleted biosolids is an effective fertilizer for row crops when applied at the agronomic rate without the potential for groundwater contamination. After repeated four years of application, Nitrate Nitrogen (NO3-N) percolation beyond the root zone in plots treated with pelleted biosolids was similar to percolation in background soil Nitrate Nitrogen (NO3-N) concentration. The practice of applying pelleted biosolids reduces the need for more costly inorganic fertilizers and enables growers to maximize the return on their nutrient management practices, potentially saving money while minimizing the adverse impact on water quality.
3. Managing forage bermudagrass hay harvests for safe and effective use of manure as fertilizer. Wide adaptation and ability to produce hay with high nutritive value make bermudagrass an ideal forage for livestock farming in the southeastern United States. Two studies determined the response of forage nutritive value and phosphorus removal in biomass to the combined effects of harvest interval and stubble height in bermudagrass fertilized routinely with poultry litter or swine lagoon effluent and associated changes in soil test phosphorus. ARS researchers in Mississippi State, Mississippi, tested this system’s effective removal of soil P on commercial swine and experimental farms. Results indicate a best management practice is cutting every 35 days at 1.2-inch residual stubble height, which has long been considered a standard for economical forage production. A cutting height of 1.2 inch consistently increased yields of biomass and nutrients, as compared to 3.5 inch. If the goal is to maximize nutrient removal, harvest should be at 6 to 10 week-intervals and as close to the ground as possible to maximize forage yield. Additionally, harvesting bermudagrass at an advanced stage of maturity is a best management practice in situations where high soil test phosphorus (manure nutrient management) is of greater concern than forage nutritive value. Results inform and provide land managers on methods to enhance bermudagrass removal of nitrogen and phosphorus in biomass and thereby reduce loss of these nutrients from hay fields receiving swine-lagoon effluent or poultry litter.
4. Lignite coal and biochar reduce ammonia emissions from broiler litter. Ammonia loss from broiler litter compromises production efficiency and potentially impacts bird health inside barns. When litter is used as a crop fertilizer, ammonia loss also equates to a lower fertilizer value and is a negative input to the biosphere. ARS researchers in Mississippi State, Mississippi, compared locally sourced lignite coal to commercially available biochar in laboratory tests with broiler litter. Higher application rates of either amendment reduced ammonia losses the most as did the smaller particle sizes studied. Broadcasting either amendment performed better than mixing it into the broiler litter. Overall, ammonia losses were reduced 47-91% by lignite, 18-42% by the larger size biochar, and 29-58% by the smaller size biochar. The potential impact is that both lignite coal and biochar are effective at reducing ammonia losses for both meat and crop production, benefiting producers and the environment. Further, producers can save labor costs by broadcasting the amendments.
5. Evaluation and calibration of soil moisture sensors in undisturbed soils. There is increasing interest and demand for growers and researchers in the state of Mississippi to use electronic soil moisture sensors for crop water management. Previous studies demonstrated large variability in soil type and associated soil properties present great challenges in the selection and deployment of sensors for accurate monitoring of soil moisture. ARS researchers in Mississippi State, Mississippi, evaluated and calibrated three soil moisture sensors on-site in fields and in undisturbed (intact) soil samples in the laboratory. Six predominant soil types from across Mississippi were selected. Results indicated the built-in factory calibrations for each of the sensors overestimated soil moisture, but generally performed better in sandy loam than clayey soils. It is imperative to calibrate sensors in situ or in undisturbed soils. Understanding that calibrations are necessary will improve model accuracies and predictive capabilities, which ultimately will aid customers and stakeholders.
6. Conserving water with cover crop in no-till systems. Because grain yield of rainfed corn–soybean annual rotation systems in the Mid-South United States of America is dependent on rainfall, minimizing water loss is key to sustainable crop productivity. Quantifying water conservation and grain yield improvements, when using winter cover crops in no-till systems, is difficult due to complex interactive effects of diverse soil types, various weather conditions, topography, and crop management practices. ARS researchers in Mississippi State, Mississippi, accounted for these interactive and long-term effects, and classified the past 80 years as “wet,” “normal,” and “dry” rainfall years and assessed water balance in the two summer crops under different rainfall patterns with and without a cover crop. In the analysis of dry years following a winter cover crop, the team found grain yield increased by 41 kg per hectare in soybean and 144 kg per hectare in corn, as compared with no cover crop. Overall estimates for a rainfed, no-till corn–soybean rotation system indicated that planting a cover crop reduced deep drainage by 16% and evaporation by 24%, and increased soil organic matter by 15% and soil water storage by 13%. This study assists growers in determining whether or not planting winter wheat could benefit corn and soybean water productivity in a given rain category year and how to optimize such benefits.
