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ARS Home » Southeast Area » Florence, South Carolina » Coastal Plain Soil, Water and Plant Conservation Research » Research » Research Project #432460

Research Project: Managing Water Availability and Quality for Sustainable Agricultural Production and Conservation of Natural Resources in Humid Regions

Location: Coastal Plain Soil, Water and Plant Conservation Research

2020 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.

Progress Report
In Sub-objective 1a, the corn irrigation experiment was completed, and a manuscript was written evaluating the use of an automated irrigation management system to control a variable rate irrigation system in the humid Eastern U.S. Coastal Plain. The automated irrigation management system was developed by ARS researchers and Engineers at Bushland, Texas. The systems are being evaluated in different climatic regions including Florence, South Carolina, Portageville, Missouri, and Stoneville, Mississippi. In Florence, crop and soil status were measured automatically using wireless infrared thermometers that were installed on the center pivot lateral to measure crop canopy temperatures and volumetric soil water content sensors to monitor soil moisture levels. These sensors measurements were integrated with weather data to estimate crop water requirements and levels of crop stress using the ARSmart Pivot software. After completion of 4-years of corn production using the ARSmart Pivot software, we have started evaluations of the system with soybean. Several scans of the soybean field have been performed and irrigation prescriptions have been developed. In Sub-objective 1b, the cotton experiment was completed, and the data is being analyzed. In the corn experiment, normalized difference vegetative indices (NDVI) measurements were collected in association with the evaluation of the ARSmart Pivot evaluation on corn (objective 1a). The NDVI data and associated irrigation depths are being compared to those prescribed by the ARSmart Pivot and soil water potential treatments. We are developing algorithms to evaluate the NDVI data to make irrigation recommendations. In sSb-objective 1c, we continued a field study to quantify the interaction of cover crops and tillage management on soil water availability and crop productivity. In Year 3, aboveground biomass was collected at four stages of corn (V6, V16, R1) and at maturity for both biomass and grain yield, and tissue analyses. On an additional study, soybean grain and tissues were also analyzed. Along with plant sampling, soil samples were collected for nutrients, carbon, and enzymes analyses. In addition, historical data from field supplemental irrigated corn experiments were used to assess water nitrogen dynamics in the Coastal Plain sandy soils using the Root Zone Water Quality Model (RZWQM), and results were published in a scientific journal. In Sub-objective 1d, this is the fourth year of data collection. DNA sequence analysis looking at the effect of introducing cover crop and tillage management practices to native fields over the first three years is currently undertaken. Over three years, significantly lower yields were seen in low electrical conductivity (EC) soils under conventional tillage practices, while conservation tillage, with and without cover crops, smoothed out yield results across all EC levels. In Sub-objective 2a, we evaluated the interactive effects of different sources of N (regular urea vs. controlled-release urea), different rates of nitrogen (0, 120, and 240 kg N/ha) with (100%) and without (0%) irrigation on grain yield, biomass, N-use efficiency of corn, and porewater quality in Coastal Plain region. In Year 3 of our study, we collected porewater, soils, and corn tissues at different growth stages of corn (V6, V16, R1, and at maturity). We also recorded and analyzed biomass and grain yield of corn in Year 3. Over three years, we consistently observed greater biomass yield and grain yield of corn when applied with controlled-release urea and 100% irrigation compared with the control. The three-year data are currently being analyzed statistically for publication. In Sub-objective 2b, a second-year field experiment was conducted to evaluate phosphorus (P) runoff potential of three P fertilizer sources directly applied on a sandy soil (Norfolk soil). A 56 mm/hr rainfall was simulated on 16 randomized block plots selected on a conservation tillage cotton field at the Clemson University’s Pee Dee Research and Education. The three fertilizer treatments consisted of triple super phosphate (treatment A), granulated recovered P from swine manure (treatment B), turkey litter ash (treatment C) and a control. Soil and runoff samples were collected for laboratory analyzes.

1. Potential water conservation using Variable-Rate Irrigation (VRI). Variable-rate irrigation systems can be used to spatially manage irrigation within sub-field-sized zones and optimize spatial water use efficiency. ARS researchers in Florence, South Carolina, used simulation modeling to evaluate the potential water savings and management zone delineation using VRI systems in the Southeastern Coastal Plains of the United States. They simulated 21 years of corn production with a VRI irrigation system on a field that had twelve highly variable soils and associated varying water holding capacities. For the overall combined 21 year simulation, they identified only two distinctly different management zones requiring significantly different irrigation applications. However, when the 21 year simulation was divided into periods with below and above average growing season rainfalls, the simulations identified up to 5 distinctly different management zones. These simulation results indicated that VRI system design and management should not be solely based on long-term average weather conditions but should consider periods with greater irrigation demands. Potential water savings varied depending on the number of management zones utilized and growing season rainfalls. These results allow irrigation designers and managers to effectively delineate VRI management zones to improve water use efficiency.

2. Precipitation analysis for rainfed agriculture. Rainfed agriculture in the Southeastern United States depends on precipitation during the growing season. Over the last two decades, signs of precipitation irregularity were frequently reported across the region. Even though the region receives a relatively high annual precipitation, the precipitation during the growing season is not equally distributed in both time and space and threatens the sustainability of the region's rainfed agriculture. ARS researchers in Florence, South Carolina, studied the historical precipitation patterns from South Carolina, North Carolina, and Georgia to understand the precipitation irregularity in the region. The analysis included seasonal precipitation totals from 1960 to 2017 at 208 stations. Three precipitation regions were identified based on statistical and similarity criteria analysis. Precipitation probability tables were generated for each of these regions. These precipitation probability tables can serve growers and extension practitioners to make decisions on rainfed or irrigation crop management according to tabulated chances of precipitation deficits or excesses.

Review Publications
Zhang, S., Yang, Y., Zhai, W., Tong, Z., Shen, T., Li, Y., Zhang, M., Sigua, G.C., Chen, J., Ding, F. 2019. Controlled-release nitrogen fertilizer improved lodging resistance and potassium and silicon uptake of direct-seeded rice. Journal of Agronomy and Crop Science. 59:1-8.
Sohoulande Djebou, D.C., Martin, J.H., Szogi, A.A., Stone, K.C. 2020. Climate-driven prediction of land water storage anomalies: An outlook for water resources monitoring across the conterminous United States. Journal of Hydrology. 588.
Sohoulande Djebou, D.C., Ma, L., Szogi, A.A., Sigua, G.C., Stone, K.C., Malone, R.W. 2020. Evaluating nitrogen management for corn production with supplemental irrigation on sandy soils of the Southeastern Coastal Plain region of the United States. Transactions of the ASABE. 63(3):731-740.
Sohoulande Djebou, D.C., Stone, K.C., Szogi, A.A., Bauer, P.J. 2019. An investigation of seasonal precipitation patterns for rainfed agriculture in the southeastern region of the United States. Agricultural Water Management. 223.
Stone, K.C., Bauer, P.J., Sigua, G.C. 2019. Potential water conservation using site-specific variable rate irrigation. Applied Engineering in Agriculture. 35(6):881-888.
Sigua, G.C., Novak, J.M., Watts, D.W., Myers Jr, W.T., Ducey, T.F., Stone, K.C. 2020. Urease activity and nitrogen dynamics in highly weathered soils with designer biochars under corn cultivation. Biochar Journal.
Sohoulande Djebou, D.C., Szogi, A.A., Stone, K.C., Novak, J.M. 2020. Watershed scale nitrate-N abatement of instream wetlands: An appraisal using the soil and water assessment tool. Applied Engineering in Agriculture. 36(3):387-397.
Lamm, F.R., Porter, D.O., Bordovsky, J.P., Evett, S.R., O'Shaughnessy, S.A., Stone, K.C., Kranz, W.L., Rogers, D.H., Colaizzi, P.D. 2019. Targeted, precision irrigation for moving platforms: Selected papers from a center pivot technology transfer effort. Transactions of the ASABE. 62(5):1409-1415.
Stone, K.C., Bauer, P.J., Oshaughnessy, S.A., Andrade, M.A., Evett, S.R. 2019. A variable rate irrigation decision support system for corn in the US Eastern Coastal Plain. In: Stafford, J.V., ed. Precision Agriculture '19. Wageningen Academic Publishers. p.673-679.
Bestelmeyer, B.T., Marcillo, G., McCord, S.E., Mirsky, S.B., Moglen, G.E., Neven, L.G., Peters, D.C., Sohoulande Djebou, D.C., Wakie, T. 2020. Scaling up agricultural research with artificial intelligence. IEEE IT Professional. 22:32-38.