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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

2022 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
This is the final report for the project 6082-13000-010-00D “Managing Water Availability and Quality for Sustainable Agricultural Production and Conservation of Natural Resources in Humid Regions” which terminated on December 28, 2021. Refer to new project 6082-13000-011-000D, "Innovative Technologies and Practices to Enhance Water Quantity and Quality Management for Sustainable Agricultural Systems in the Southeastern Coastal Plain." Variable rate irrigation (VRI) system management. Variable rate irrigation is a method of irrigating different field areas with different application depths. This type of irrigation method is suitable for the humid US Eastern Coastal Plain region, where soils are typically sandy with low water holding capacity and are highly spatially variable. Managing VRI systems is more complicated than uniformly applying the same application depth to the entire field. To assist in managing these VRI systems, ARS researchers in Florence, South Carolina, evaluated the use of a decision support system (DSS) for managing Variable Rate Irrigation on the region’s spatially variable sandy soils. The DSS integrated remotely sensed crop canopy temperatures and soil water sensors to develop irrigation recommendations. The DSS irrigation recommendations were compared to traditional management using only soil moisture sensing. 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 further evaluate and refine this new decision support system for irrigation scheduling as a tool for growers to optimize water use and manage their irrigation systems. 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 with 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. Irrigation Management to protect water quality. Although agriculture is one of the largest sources of nutrient losses into the environment, mainly crop nitrogen fertilization, proper irrigation management can reduce nutrient leaching while maintaining crop yield. A three-year corn field study was conducted to evaluate the effects of three irrigation scheduling methods and two nitrogen rates on pore water nitrate and phosphate in four soil types with corn production in U.S. Coastal Plain Region. Although, soil pore water nitrate varied significantly, irrigation scheduling with an expert system had the lowest mean soil water pore nitrate compared to traditional irrigation scheduling methods. Soil water pore phosphate was not affected by the irrigation scheduling method. Using an expert system for irrigation management resulted in lower soil water pore nitrate and phosphate concentrations. These results indicate that the irrigation scheduling method may be a way of achieving optimum yields while potentially minimizing potential nutrient losses. Improved sorghum productivity in Coastal Plains soils. The U.S. eastern Coastal Plain produces a large quantity of poultry and livestock, and much of the grain used to feed these animals is imported. An emphasis by the livestock producers to reduce imported grains in the eastern Coastal Plains, required an increase in regional grain production with grain sorghum. Sorghum production in the US Central and semi-arid Southern High Plains has dramatically increased with the widespread use of irrigation, greater fertilizer usage, and adapted hybrids. However, little is known about the grain sorghum response to the combined effects of irrigation and nitrogen fertilization in the humid U.S. Coastal Plains region. Scientists in Florence, South Carolina studied supplemental irrigation and nitrogen fertilization in grain sorghum production. Although, they found no overall increase in harvested grain from supplemental irrigation, they found increased nitrogen applications and supplemental irrigation increased grain sorghum biomass accumulation, nitrogen uptake, and nitrogen use efficiency. These results will assist the Coastal Plains region’s grain producers manage irrigation and nutrients in grain sorghum production. 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 scientists 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 phosphorus and potassium concentrations 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 manage nutrients and agricultural waste products. Precipitation analysis for Rainfed Agriculture. Rainfed agriculture in the Southeastern United States depends on precipitation during the growing season. Over the last two decades, precipitation irregularity occurred 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, and precipitation probability tables were generated for each of these regions. These precipitation probability tables can serve growers and extension practitioners to decide on rainfed or irrigation crop management according to tabulated chances of precipitation deficits or excesses. Precipitation-based decision support for agricultural irrigation management. Louisiana’s relative abundance of water resources 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 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 two distinct precipitation regions in 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. In the newly developed objective 3, four different cover crop treatments, two of which involved perennial clovers adapted to heat and drought stress were established. Soil moisture, temperature, and electrical conductivity were quantified and weed suppression, cotton morphology, lint yield, and fiber quality were assessed.


Review Publications
Sohoulande Djebou, D.C., Awoye, H., Nouwakpo, S.K., Dogan, S., Szogi, A.A., Stone, K.C., Martin, J.H. 2022. A global-scale assessment of water resources and vegetation cover dynamics in relation with the earth climate gradient. Remote Sensing in Earth Systems Sciences.
Lamm, F.R., Dukes, M.D., Stone, K.C., Mecham, B.Q. 2021. Beyond 2020, vision of the future: Selected papers from the sixth decennial National Irrgiation Symposium. Transactions of the ASABE. 64(5):1449-1458.
Ahn, J., Briers, G., Baker, M., Price, E., Sohoulande Djebou, D.C., Strong, R., Piña, M., Kibriya, S. 2022. Food security and agricultural challenges in West African rural communities: a machine learning analysis. International Journal of Food Properties. 25:827-844.
Billman, E.D., Alexandre De Souza, I., Smith, R.G., Soder, K.J., Warren, N.D., Andrade Teixeira, F., Brito, A.F. 2021. Winter annual forages fill spring productivity gaps in grazing or hay operations. Crop, Forage & Turfgrass Management. Article e20113.