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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

2021 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. 3. Develop innovative cropping systems and rotations to improve water and nutrient use efficiency, profitability, climatic resiliency, and reduce environmental impacts.

The overall goal of this project is to improve water and nutrient management in humid regions. The research focuses on three 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. The third objective is to identify, develop, and evaluate novel cover and row crop productions systems for the region. In this objective, we will develop and evaluate novel cover crop systems that can be used to improve and enhance existing row crop systems, improve water use efficiency, and be utilized for grazing and forage production. 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 initial corn irrigation experiment has been completed and a manuscript was written evaluating the use of ARS Irrigation Scheduling Supervisory Control and Data Acquisition (ISSCADA) system to automate and manage variable rate irrigation systems in the humid Eastern US Coastal Plain. In 2020 and 2021, we began evaluations of the performance of the ISSCADA system with soybean. Initial year results indicated increased yield with irrigation compared to rainfed treatments and increased irrigation water use efficiency using the ISSCADA system. This experiment is being repeated in 2021. In Sub-objective 1b, the cotton experiment was completed, the data is being analyzed, and a manuscript is in preparation. In the corn experiment, normalized difference vegetative indices (NDVI) measurements were collected in association with the evaluation of the ISSCADA system evaluation on corn (Objective 1a). The NDVI based irrigation depths are being compared to those prescribed by the ISSCADA decision support system. In Sub-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 4, 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. Analyses of soil and plant samples were completed. Data are being analyzed and results are being interpreted for publication in a scientific journal. In Sub-objective 1d, analysis of the effects of introducing cover crop and tillage management practices to microbial structure and function in native fields over the first four years is continuing. Examination of microbial function via soil extracellular enzyme analysis did not reveal any influences on microbial activity by cover crop or tillage management practices, while microbial structure as measured by DNA sequencing is ongoing. Significantly lower cotton yields were observed in low electrical conductivity (EC) soils under conventional tillage practices, while conservation tillage, with and without cover crops, stabilized yield results across all EC levels. In Sub-objective 2a, the field experiment on 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 was completed. We collected porewater, soils, and corn tissues at different growth stages of corn (V6, V16, R1, and at maturity). All the laboratory analyses for soil, water and plant samples were completed; data are currently being analyzed statistically for publication. We also recorded and analyzed biomass and grain yield of corn. Over the duration of the field study, we consistently observed greater biomass yield and grain yield of corn when applied with controlled-release urea and 100% irrigation compared with the control. Urea treated plots had greater amount of pore water nitrate than the slow release fertilizer and the control. In Subobjective 2b, laboratory analyses of the total phosphorus (P) and soluble reactive P in runoff samples collected during the two-year field experiment were completed. Specifically, the runoff samples were digested using nitric acid with peroxide adapted to a block digester. Total P in the digests were quantified by inductively coupled plasma. For each runoff sample, a sub-sample was filtered through a 0.45µm pvdf filter and subsequently analyzed for soluble reactive phosphorus by the malachite green method. Additional laboratory analyses were conducted on soil samples collected during years 2019 and 2020 field experiments to appraise P movement in the soil following the rainfall simulations. Thus, for each plot, two soil layer samples including layers 0-6 inches and 6-12 inches were analyzed in laboratory to determine Plant Available Phosphorus in the soil based on Mehlich 1 extracts. Data resulting from the laboratory analyses were processed along with the volumetric runoff measurements. Statistical analyzes are being conducted to elucidate the disparities in the runoff potential of the treatments consisting of a control (treatment A), triple super phosphate (treatment B), granulated recovered P from swine manure (treatment C), and turkey litter ash (treatment D). Partial results are reported as a proceeding paper and presented at the 2021 ASABE annual conference. The full manuscript reporting the study will be submitted for publication in a peer reviewed journal. In Objective 3, perennial and annual cover/forage crop plots for the pilot-scale study were established in October 2020 at the Clemson University Pee Dee Research and Education Center. Following successful establishment, plots were maintained over winter months, then measured for crop and weed populations, and sward heights. Additionally, two biomass samplings occurred for each treatment in late March and mid-April. All plots were then mowed to 5 cm to remove excess biomass, and the fallow and annual ryegrass plots were terminated with glyphosate. Strip tillage of plots occurred in early May, with cotton planting occurring on May 15. The TDR 315 moisture probes have also been installed in one replication to monitor differences in soil moisture due to varying cover crop/forage treatments. Upcoming readings will include cotton leaf moisture readings, weed population assessments, plant mapping, and cotton harvest in fall of 2021.

1. Variable rate irrigation (VRI) system management. Due to the region’s sandy soils, water is often the most limiting factor for production agriculture in the US Eastern Coastal Plain. Additionally, limited water resources necessitate careful managing of timing and quantity of irrigation events. To address these problems, ARS researchers in Florence, South Carolina, evaluated the use of a decision support system for managing irrigation. The decision support system integrated crop canopy temperatures and soil water sensors to develop irrigation recommendations. During years with low rainfall, irrigation management using both the canopy temperatures and soil water content data to determine plant water needs produced greater corn yields and used less water than standard irrigation scheduling methods. The results of this work will help to further evaluate and refine this new decision support system for irrigation scheduling as a tool for growers to use in managing their irrigation timing and water usage.

2. Precipitation-based decision support for agricultural irrigation management. The relative abundance of water resources in Louisiana has created poor agricultural water management practices as farmers commonly opt for low efficiency irrigation methods such as furrow and flood irrigation. While these low efficiency irrigation systems are less costly, they often use considerably more water than necessary to meet crop needs and may deplete the state’s aquifers. To better manage irrigation water management, the Louisiana State University’s Agricultural Center has consulted with ARS researchers in Florence, South Carolina, to develop a precipitation-based decision support tool for irrigation management in Louisiana. This work found that there are two distinct precipitation regions of Louisiana, and provided recommendations for irrigation of corn, soybean, cotton, grain sorghum, and sugarcane under early and late planting. Results from this study were delivered to the Louisiana State University’s extension service for use in their educational programs. This research provides growers and farm managers with a tool to better manage and conserve water.

Review Publications
Sigua, G.C., Stone, K.C., Bauer, P.J., Szogi, A.A. 2020. Efficacy of supplemental irrigation and nitrogen management on enhancing nitrogen availability and urease activity in soils with sorghum production. Sustainability.
Stone, K.C., Bauer, P.J., Oshaughnessy, S.A., Andrade-Rodriguez, A., Evett, S.R. 2020. A variable-rate irrigation decision support system for corn in the U.S. Eastern Coastal Plain. Transactions of the ASABE. 63(5):1295-1303.
Parajuli, B., Luo, M., Ye, R., Ducey, T.F., Park, D., Smith, M., Sigua, G.C. 2021. Aggregate distribution and the associated carbon in Norfolk soils under long-term conservation tillage and short-term cover cropping. Communications in Soil Science and Plant Analysis. 52:859-870.
Ippolito, J.A., Cui, L., Kammann, C., Wrage-Monnig, N., Estavillo, J.M., Fuertes-Mendizabal, T., Cayuela, M., Sigua, G.C., Novak, J.M., Spokas, K.A., Borchard, N. 2020. Feedstock choice, pyrolysis temperature and type influence biochar characteristics: a comprehensive meta-data analysis review. Biochar. 2:421-438.
Parajuli, B., Ye, R., Luo, M., Ducey, T.F., Park, D., Smith, M., Sigua, G.C. 2021. Contrasting carbon and nitrogen responses to tillage at different soil depths: An observation after 40-year of tillage management. Soil Science Society of America Journal. 85,4:1256-1268.
Novak, J.M., Watts, D.W., Sigua, G.C., Ducey, T.F. 2021. Corn grain and stover nutrient uptake responses from sandy soil treated with designer biochars and compost. Agronomy. 11(5):942.
Sohoulande Djebou, D.C., Conger, S., Szogi, A.A., Stone, K.C., Martin, J.H. 2021. Seasonal precipitation pattern analysis for decision support of agricultural irrigation management in Louisiana, USA. Agricultural Water Management. 254.
Ye, R., Parajuli, B., Szogi, A.A., Sigua, G.C., Ducey, T.F. 2021. Soil health assessment after 40 years of conservation and conventional tillage management in Southeastern coastal plain soils . Soil Science Society of America Journal. 85,4:1214-1225.
Evett, S.R., O'Shaughnessy, S.A., Andrade, M.A., Colaizzi, P.D., Schwartz, R.C., Schomberg, H.H., Stone, K.C., Vories, E.D., Sui, R. 2020. Theory and development of a VRI decision support system: The USDA-ARS ISSCADA approach. Transactions of the ASABE. 63(5):1507-1519.