Location: Coastal Plain Soil, Water and Plant Conservation Research2019 Annual Report
1. Develop effective irrigation and crop management techniques that increase profitability, conserve water, and protect water quality in surrounding ecosystems. 1a. Evaluate the potential use of the ARS Irrigation Scheduling and Supervisory Control and Data Acquisition System (ISSCADA) for variable rate irrigation management of corn in the humid Southeastern U.S. 1b. Evaluate variable rate irrigation using crop feedback for site-specific irrigation management in the Southeastern U.S. Coastal Plain. 1c. Quantify how cover crops and tillage affect soil water availability, soil pore water nitrogen, and crop productivity. 1d. Evaluate how water availability and microbial population dynamics are influenced by soil improvement practices on a spatial basis. 2. Assess the effects of innovative management and production practices on nutrient losses via hydrologic pathways from farms and watersheds. 2a. Quantify nitrogen balance, water-use efficiency and crop yield of irrigated and rain-fed corn as affected by fertilizer management strategy in the Southeastern U.S. Coastal Plain. 2b. Determine the runoff potential of recovered P sources when surface applied as fertilizer in no-tillage systems.
The overall goal of this project is to improve water and nutrient management in humid regions. The research focuses on two main objectives. The first objective is to develop effective irrigation and crop management techniques that increase profitability, conserve water, and protect water quality in surrounding ecosystems. In this objective, we will evaluate the potential of using within season crop feedback for managing variable-rate irrigation (VRI) systems and also evaluate the use of an automated VRI system for managing irrigations. For rain-fed production, we will investigate how soil conservation practices affect nitrogen cycling, soil microbial populations that influence soil carbon cycling, and soil water availability. The second objective is to assess the effects of innovative management and production practices on nutrient losses via hydrologic pathways from farms and watersheds. In this objective, we will investigate N fertilizer management under irrigated and rain-fed conditions for nutrient use efficiency and potential loss of N to the surrounding ecosystem. We will also evaluate the potential of reducing dissolved P in runoff from fields managed with conservation tillage by applying recovered P fertilizer products that have low water solubility. Research methods include field and laboratory experiments, demonstrations, and leading-edge analytical techniques. The research outlined in this project addresses components of two of the four problem areas identified in the ARS - Water Availability & Watershed Management National Program Action Plan. Research products will consist of water and nutrient management practices that conserve water, sustain production, and enhance environmental quality. These products will also provide information vital to national water management and water quality policies. The expected benefits of the research program are the long-term conservation and protection of the nation’s water resources. Conservation and protection of the nation’s water resources will ensure production of food and fiber for current and future populations in an economically viable and environmentally sustainable manner.
The corn irrigation experiment is in its third year of evaluating the use of an automated irrigation management system to control a variable rate irrigation system developed by ARS. The automated irrigation management system (ARSmart Pivot) was developed by scientists and engineers at Bushland, Texas, under a cooperative research and development agreement (CRADA). In Florence, South Carolina, wireless infrared thermometers were installed on the center pivot lateral to measure crop canopy temperatures. Volumetric soil water content sensors along with soil water potential sensors were installed to monitor soil moisture levels. These sensors were integrated with weather data to estimate crop water requirements and levels of crop stress using the ARSmart Pivot software. Several scans of the corn field have been performed and irrigation prescriptions have been developed and utilized. The experiment will evaluate the use of the integrated crop water stress index-based management system and investigate how it may need to be modified for humid regions. Last year we installed brackets to mount normalized difference vegetative index (NDVI) sensors for spatially calculating crop coefficients to manage spatial irrigations. This year we are continuing to collect NDVI measurements for potential integration with the ARSmart Pivot software. Additionally, we are using a hybrid management that utilized combined soil water content sensors and canopy temperature sensors for developing irrigation prescriptions. A cotton irrigated experiment evaluating the potential for using crop reflectance (NDVI) to manage variable rate irrigations was completed. The NDVI measurements were converted into spatial crop coefficients and used for creating prescription maps for variable rate irrigation applications. Initial results showed that using variable rate irrigation reduced total water applied during these applications but did not impact yield above rainfed levels. The data from the experiment is being summarized and analyzed. An ongoing field study to quantify how cover crops and tillage affect soil water availability and crop productivity continued. Aboveground corn samples were collected at four stages of corn: V6, V16, R1, and at maturity for corn biomass and tissue analyses. Soybean grain and tissue were also analyzed. The yield of corn and soybeans were also recorded. Along with plant sampling, soil samples were also collected for nutrients, carbon, and enzymes analyses. Soil variability analysis study is in its third year of data collection. Soil and plant samples have been collected at the Florence, South Carolina location and are currently being analyzed. Microbial data for both the soil rhizosphere and root-associated populations is being conducted. Data from the first two years of the study indicate shifts in fungal to bacterial ratios as assess by phospholipid fatty acid (PLFA) analysis. After cotton harvesting, DNA sequencing of all three years samples will occur to look at in-depth changes in microbial community structure. These data will be paired with microbial community function (soil microbial enzyme activity), soil and plant nutrient data, as well as soil water potentials, and soil temperature measurements in order to assess observable differences in soil management practices. Ongoing field study that began in 2017 was aimed to evaluate the effect of different rates (0, 120, and 240 kg N/ha) and sources of N (urea vs. controlled-release urea) with and without irrigation on grain yield, biomass, and N-use efficiency of corn in Coastal Plain region. Our early results indicated significant interaction effects amongst sources, rates of N fertilizers and irrigation management on corn biomass. We observed greater biomass of corn when applied with controlled-release urea and 100% irrigation. Corn was planted on April 18, 2019, for our third year of field study. As we did during the second year of study, we will collect porewater, soils, and corn tissues at different growth stages of corn (V6, V16, R1, and at maturity), biomass, and grain yield. A field experiment was conducted to evaluate the effect of runoff on phosphorus (P) leaching following a direct application of turkey litter ashes as P fertilizer. A rainfall simulator was built and used to simulate rainfall a 56 mm/hr rain on 16 randomized block plots selected on a conservation tillage cotton field at the Clemson University’s PeeDee Research and Education Center. Three treatments consisting of triple super phosphate (treatment A), granulated recovered P from swine manure (treatment B), turkey litter ash (treatment C) and a control were applied to address runoff effect on phosphorus leaching from turkey litter ashes.
1. A variable rate irrigation decision support system for corn in the U.S. eastern coastal plain. Variable rate irrigation is a method of irrigating where water is applied to different areas of fields at different application depths. This type of irrigation is more complicated than uniformly applying the same application depth to the entire field. To assist growers in managing these variable rate irrigation systems, ARS researchers in Florence, South Carolina, developed a decision support system to manage these spatial water applications. In this research, we evaluated this decision support system in the humid southeastern U.S. coastal plain region. The decision support system used both soil and plant sensors to manage the irrigations and was compared to a traditional management using only soil moisture sensors. Corn yields and irrigation depths applied with the decision support system were similar to the traditional management system. These results on the use of the decision support system that incorporates crop stress and available soil moisture will improve and optimize the utilization of water for crop production in the humid southeastern U.S. Coastal Plain.
2. Fertilizer efficacy of poultry litter ash blended with lime or gypsum as fillers. Incineration of poultry litter is being used both to produce energy in power plants and as a method of waste handling and treatment in areas with high concentrations of poultry production. With its relatively high concentration of plant nutrients, poultry litter ash is a power plant byproduct with potential use as fertilizer. However, environmental concerns exist about the need to uniformly land-apply poultry litter ash. ARS researchers in Florence, South Carolina, evaluated if blending ash with two potential filler materials affected soil and plant parameters and their possible impact on field application patterns with a spinner disc applicator. The two potential fillers evaluated, calcitic lime and flue gas desulfurization gypsum (FGDG), appear to be appropriate filler materials for land-applying the ash. Neither of these materials negatively affected plant-available concentrations of phosphorus and potassium in the soil, nor ryegrass biomass and plant phosphorus and potassium concentrations. Field tests of uniform distribution showed that poultry litter ash application using a commercial fertilizer spreader is feasible for ash alone or blended with calcitic lime or FGDG. These results will assist the region’s producers in managing nutrients and agricultural waste products.
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