Project : USDA ARS

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Research Project: Optimizing the Management of Irrigated Cropping Systems in the Lower Mississippi River Basin

Location: Delta Water Management Research

2025 Annual Report

Objectives
1. Develop improved management practices for irrigated cropping systems (e.g. rice, soybean, cotton) in humid subtropical environments. 1a. Develop and evaluate irrigation management systems and determine their influence on crop yield and quality, and water quality. 1b. Determine impacts of conservation management practices on crop yield, quality and climate resiliency, greenhouse gas emissions, and air and water quality. 2. Develop and expand robust datasets focused on water use efficiency, air and water quality, greenhouse gas emissions, and other sustainable cropping system metrics in humid subtropical environments. 2a. Contribute to long-term water quality assessments of cotton- and rice-based cropping systems. 2b. Integrate greenhouse gas emission, yield metrics, and phenotypic architecture datasets to improve models, scaling factors, and tools for current and future climate scenarios. 3. Develop and deploy agronomically sound irrigation and drainage management tools, practices, and technologies that improve water resource management and return on investment in a changing climate. 3a. Devise techniques and/or tools to identify, inventory, and create conservation milestones for agricultural water resource management in the Lower Mississippi River Basin (LMRB). 3b. Evaluate the utility of multiple strategies for managed aquifer recharge in the Lower Mississippi River Basin (LMRB).

Approach
To optimize the management of irrigated cropping systems in the Lower Mississippi River Basin, research must aim to sustain or improve agricultural production and natural resources through optimized management practices that sustain yield and grain quality while reducing inputs and environmental risks. Research will focus on field-scale to farm-scale quantification of water quantity, water quality, and greenhouse gas emissions in response to crop management. Comparisons of production practices in rice-based and cotton-based systems include irrigation automation, nutrient management, crop establishment, tillage, cover crops, and residue management will be investigated. Improved understanding of aquifer decline and solutions to arrest decline through watershed planning that focuses on return on investment and managed recharge will be studied. Data collected on the impact of these practices will be curated into robust datasets that will be used to devise tools and technologies and improve existing models. This research is expected to augment the existing body of knowledge of agricultural water resources, inform resource managers and provide farm managers with new tools, practices and technologies that will reduce groundwater use and produce a profitable crop.

Progress Report
Progress was made under Objective 1 in improving management practices for irrigated cropping systems in humid subtropical environments. In rice, a review paper was published in a high impact journal that highlights the role of hybrid rice in advancing rice production. Additional publications for this objective include the impact of rice irrigation on yield and water use efficiency, industry solutions to reducing arsenic in rice grains, modeling rice plant components, and management and irrigation in the rice-soybean rotation. Irrigation automation research continued and an ARS Researcher at Jonesboro, AR leads the Mid-South Irrigation Automation Working Group, an organization made up of private, university, and government entities. An ARS researcher at Jonesboro, Arkansas presented studies on efficient rice management at 2025 Tri- Societies of America Scientific Meeting and a graduate student received two awards for their work. ARS Researchers at Jonesboro, Arkansas presented their work describing irrigation research at the 2nd Annual Field Day of the University of Arkansas Northeast Arkansas Rice Research and Experiment Station, Rice Technical Working Group (RTWG) Meeting, Prairie County Conservation Day, and Arkansas Soil and Water Education Conference. Scientists continue to advise on the Arkansas Water Plan and University of Arkansas Irrigation Contest-“More Crop per Drop”. Industry and NGO interest in the unit’s research is evidenced by collaboration and significant contact with the Mars Corporation, The Nature Conservancy, USA Rice, Ricetec, Inc, and the Arkansas Rice Federation. In addition, the unit has received incoming funds from multiple sources including Rice Tec, Inc., Grantham Foundation, USDA-NRCS, Cotton, Inc, and others. Their work has been highlighted in the popular press, including the Delta Farm Press. Two ARS Researchers from Jonesboro, Arkansas were newly invited to serve on the Technical Advisory Committee of Field to Market Sustainability Group and one now serves as the ARS at-large member to the executive board of the Rice Technical Working Group. An ARS Researcher at Jonesboro, AR was recognized as the 2024 Engineer of the Year by the Arkansas Chapter of the American Society of Agricultural and Biological Engineers for her work in irrigation while another was invited to serve as an Associate Editor of Irrigation Science. Under Objective 2: The unit continues to work toward the development and expansion of robust data sets that focus on water management, trace flux, and other resilience metrics. Progress on edge-of-field and instream water quality data curation continue. A manuscript on water quality modeling using edge-of-field data was published. Additional publications for this objective used curated data sets generated by ARS Researchers at Jonesboro, Arkansas and contributed to evapotransporation datasets across the continuous United States, global wetland methane measurements, paddy rice methane, carbon budgets in cotton across the United States, and clustering analysis of meteorological measurements. Recognition of the ARS Researchers at Jonesboro, Arkansas expertise in the area of agricultural resilience continues through data sharing agreements established with University of Arkansas, University of Maryland, Colorado State University, Auburn University, Lawrence Berkley National Laboratory, Mitti Labs, and North Carolina A&T University. An ARS Researcher at Jonesboro, Arkansas was invited to propose and ultimately to lead an international scientific workshop on nutrient dynamics in rice to develop a universal methodology to quantify yield, nutrient losses, and flux. ARS Researchers continue to serve as mentors through various official avenues, including but not limited to American Society of Agronomy and Foundation for Food and Agricultural Research (FFAR). An ARS Researchers at Jonesboro, Arkansas was asked to serve by FFAR project manager to review international research proposals for the Efficient Fertilizer Consortium. Progress was made underObjective 3 on the development and deployment of agronomically sound irrigation and drainage management tools, practices, and technologies to improve water resources management and return on investment. Two publications for this objective highlight the use of neural networks for identifying irrigation management in rice and the use of surface water irrigation reservoirs in order to improve groundwater recovery. New LiDAR imagery has been delayed but is expected for much of the region of interest, which will further our capacity to identify land levelling changes on the landscape. Progress on the Managed Aquifer Recharge project has also been made in the fourth year of water injection. Results are promising and significant effort has been directed to the modeling of the system and automating injection with a siphon system. This work to date was presented at the 2nd Annual Arkansas Groundwater Summit and a graduate student received an award for their presentation of the work at the Beltwide Cotton Conference. An ARS researcher at Jonesboro, Arkansas participated in an Interagency Managed Aquifer Recharge effort led by the EPA. ARS researchers at Jonesboro, Arkansas have been actively engaged in building management scenarios of the Mississippi Alluvial Plain modeling effort to highlight options for reducing or arresting aquifer decline in the region. An ARS Researcher at Jonesboro, AR is an active member of the Life Cycle Analysis group that meets regularly to exchange ideas in this quickly evolving field.

Accomplishments
1. Multiple benefits from innovative irrigation management in rice. Traditional rice production uses continuous flooding to provide water for growth, control pests and improve fertilizer performance. However, growing water scarcity concerns drive the need to produce rice with less water. An ARS researcher at Jonesboro, Arkansas and colleagues from Brazil compared intermittent rice flooding with continuous flooding. Intermittent flooding uses carefully-timed, shallow irrigation applications to supply rice with water amounts closer to what is needed to produce grain. Here, intermittent flooding reduced irrigation use by up to 76% relative to conventional flooding. Because irrigation use decreased while grain yield remained unchanged, water use efficiency increased by 300%. Another benefit of intermittent flooding is that field runoff is reduced. Here, runoff was reduced by 56%, showing that intermittent flooding can improve both water quantity and quality aspects of rice farming.

2. Cutting-edge agronomic techniques and plant engineering are needed to maintain high yield performance under challenging environments in irrigated rice. Over 3.5 billion people globally rely on rice as their main food staple. In Arkansas, rice is a major agricultural commodity contributing over $1 billion annually. Abiotic stress is a global problem facing humanity brought by declining water resources for rice production. An ARS Researcher at Jonesboro, Arkansas and colleagues from the International Rice Research Institute provided in-depth review of principal drivers of C and N losses, improved rice-based farming systems and development of hybrid cultivars that slow down the harmful effects of abiotic stresses in rice. Synergistic approaches that optimize the management of crop residue, water, and fertilizer N are the fastest and most effective practices to optimize nutrient availability and high crop yield. Deeper understanding of soil microbiome that controls nutrient transformations using emerging cutting-edge technologies like artificial intelligence, breeding techniques, genomic selection, environment-friendly modification of genetic material of rice have the potential to identify and develop cultivars with high productivity returns. Modern breeding programs for abiotic stress and assessment and implementation of conservation farming are valuable resources for breeders, geneticists, farmers, policy makers, and the public.

3. Synthesis of knowledge of arsenic in rice provides solutions for future management for US rice farmers. Rice is the primary staple food for more than half of the world’s population. Rice production in the US is concentrated in six states with Arkansas growing over half of US rice. Given the plant structure and management, rice plants accumulate arsenic (As) and sometimes develop grain As levels high enough to be detrimental to human health. In the US, there was a need to consolidate information on how management impacts As levels in rice. Therefore, we performed an extensive literature review of different methods for reducing the level of As in rice. In addition, we interviewed stakeholders to determine current awareness of and barriers to the implementation of mitigation practices. Scientists from the University of Arkansas, University of Delaware and an ARS unit in Jonesboro, Arkansas found that the most effective and broadly applicable practices were irrigation methods with aerobic periods such as alternate wetting and drying (AWD) and the application of silicon-rich amendments. Stakeholders indicated that the implementation of mitigation practices is most hindered by practicality and cost, and emphasized the need for cheaper and faster testing for grain As. These results are beneficial to rice producers and regulators to set achievable As limits in the food supply, particularly for rice used in the production of food products for vulnerable populations such as infants and young children.

4. Modeling of soil and nutrient loss informs management. Soil erosion and nutrient pollution contributes to billions of dollars of economic loss in the United States. These losses are in the form of diminished property values, reduced recreational use, and diminished fishing productivity in addition to increased water treatment needs. In order to combat this loss, US farmers often plant cover crops to help protect the soil and reduce pollution from their fields. However, understanding the impact of these practices is both expensive and time consuming to measure directly. Therefore, scientists can use computer programs to predict how much pollution might flow from the fields. In this project, ARS researchers at Jonesboro, Arkansas and scientists from North Carolina State Agriculture and Technology University used a program called the Agricultural Policy Environmental eXtender (APEX) to predict the amount of sediment and nutrients leaving the fields. The results showed that the program is very accurate at these predictions. This means we can use this program to estimate pollution levels decrease by cover crops instead of taking expensive measurements each time, saving both time and money. Additionally, planting cover crops helps to reduce water pollution from the field, which benefits aquatic organisms, animals that drink that water, and humans.

U.S. DEPARTMENT OF AGRICULTURE

Delta Water Management Research: Jonesboro, AR