Project : USDA ARS

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Research Project: Development of Best Management Practices, Tools, and Technologies to Optimize Water Use Efficiency and Improve Water Distribution in the Lower Mississippi River Basin

Location: Sustainable Water Management Research

2025 Annual Report

Objectives
1. Develop robust datasets, models, and data visualization tools to determine the impact of alternate water supplies on aquifer recharge and groundwater levels in the LMRB. 1.A. Implement sensing device to monitor ground water and surface water level in the Mississippi Delta. 1.B. Monitor status of surface water storage using remote sensing technology. 1.C. Quantify and characterize demand for irrigation water and identify the value of water in competing and complementary agricultural water uses. 1.D. Modeling the impact of alternate water supplies on aquifer dynamics. 2. Develop optimized irrigation scheduling tools for cropping systems in the LMRB that account for crop water requirements, impacts of water stress, and economic and environmental sustainability while minimizing water usage. 2.A. Develop and evaluate improved sensor-based irrigation scheduling methods. 2.B. Implement and evaluate, automation and other advanced technologies and methods for optimal irrigation management. 3. Develop new and novel sensor systems and that include optimized telemetry and efficiently integrate with decision support models and tools for prescription irrigation and water resource management. 3.A. Integrating ground-based sensor and remote sensing systems and cloud-based data acquisition, develop and evaluate decision support systems for site-specific irrigation and nutrient management. 3.B. Develop new sensing and monitoring systems to provide measurements of soil- and surface-water status and plant response and stress for continuous, site-specific water and crop management. 4. Evaluate and improve current best management practices or develop new practices based on new and novel approaches that stochastically account for interaction effects of irrigation, planting, fertility and pest management, and implementation of conservation practices including cover crops, tillage methods, edge-of-field buffers, surface water storage/use, and soil health. 4.A. Evaluate the effects of irrigation water sources, application techniques, and scheduling methods on crop production, environmental outcomes, and farm profitability. 4.B. Determine the water-related effects of crop management strategies such as crop/variety selection, and cover crops on crop production, environmental outcomes, and farm profitability. (See postplan for subobjective 4.C.) 5. Engage LMRB stakeholders through our MSU research and Extension partners to characterize producer behavior and attitudes with respect to irrigation and water conservation management and introducing them to cutting edge digital tools, technologies, and best management practices. (See postplan for subobjectives 5.A and 5.B.) 6. Develop and validate algorithms/models using remote sensing and eddy covariance methods to improve evapotranspiration (ET) estimates and water productivity at field and regional scales to improve the predictability and forecasting capabilities of the LMRB cropping systems models to irrigate more efficiently and reduce withdrawals from groundwater (See postplan for subobjectives 6.A. and 6.B.)

Approach
New sensing systems for the automated monitoring of surface water using ultrasonic and LiDAR distance sensors will be developed. Field experiments will be conducted to monitor surface water storage bodies across the Mississippi Delta region using novel sensors as well as UAV and/or satellite imagery. Economic studies will be carried out to identify the factors which influence groundwater pumping decisions in addition to the cost of pumping water. Groundwater and economic studies will combine to examine the impact of alternate water supplies, such as tailwater recovery systems, on aquifer dynamics and agricultural productivity. Variable rate irrigation (VRI) experiments will be conducted to examine options for reducing withdrawals from the aquifer without negatively impacting agricultural productivity. VRI management will be conducted by integrating sensor data with crop yield and water efficiency data. Crops will be grown in fields equipped with eddy covariance (EC) system for measuring water vapor and CO2 fluxes, and instrumentation for monitoring ET using a residual energy balance (REB) approach. Relevant data will be collected and analyzed to predict impacts of precipitation variability on production and water requirements in cropping systems. Sensors to monitor canopy temperature and reflectance will be deployed and used to develop vegetation indices. Plant physiological and morphological responses will be monitored. Water stress indices based on canopy temperature, NDVI, PRI, ET, and soil water will be developed and related to the crop physiological responses. Sensor development will be integrated into the agricultural production trials to develop improve irrigation prescriptions and decision support models. Additional field experiments will be conducted to examine the impact of irrigation application technique, row spacing and production techniques and methods. Additional studies will quantify changes in water use and water quality based on cover crops and fertilizer management practices. Site specific and one-on-one learning opportunities will be employed to familiarize producers who are interested in adopting the newly developed techniques. Diverse technology transfer materials and extension programming materials will be developed and delivered to target audiences through a wide array of outlets to maximize technology awareness and adoption. A combination of interviews, focus groups, and survey instruments will be developed to understand current attitudes towards conservation and best management practices. The target population for this study is all permit holders, landowners, and operators who withdraw water for agricultural irrigation in the Bootheel of Missouri and the Delta regions of Arkansas, Mississippi, and Louisiana. This approach allows for intuitive and explicit modeling of non-economic factors that influence economic decisions and behaviors. The findings will inform and guide our research and promotion efforts in relation to developing best management practices for the region.

Progress Report
Substantial progress was made on this project. Multiple projects worked towards addressing Objective 1, including the design of a cost-effective sensor system for surface water level monitoring to determine the impact of using surface water as an alternative water supply in place of groundwater withdrawals. This system utilizes open-source hardware and software, along with ultrasonic sensors and liquid level transmitters, all integrated with a microcontroller. Additionally, an inventory of on-farm water storage systems was conducted over multiple years in the Big Sunflower River Watershed using geospatial technologies, including high-resolution satellite imagery. Geo-referenced datasets with soil, crop, hydrologic,and climate data for 2017-2023 have been acquired from the Mississippi Department of Environmental Quality, CropScape, and the United States Geological Survey to help characterize demand for irrigation water and identify the value of water in competing and complementary agricultural water uses. As part of the effort to model the impact of alternative water supplies on aquifer dynamics, flow meters, rain gauges, runoff auto-samplers, and level loggers have been collecting data from a tailwater recovery system in Sunflower County, Mississippi for four years. The initial model for the system has been built, and the irrigation source and field water routing system for the model are being configured. Researchers in Stoneville, Mississippi have been collaborating with researchers in Arlington, Texas; Dallas, Texas; Tyler, Texas; and Brookings, South Dakota on the development of low-cost sensors for use in monitoring agricultural fields and crop status. These low-cost sensors, utilizing “system-on-a-chip” technologies, are designed to enable more widespread crop monitoring at a lower cost than current methods. One approach utilizes custom chips with lab-grown carbon nanotubes to produce a sensor capable of monitoring gas fluxes in a field. This sensor has lower precision than commercially available sensors but also costs less than 2% of currently available sensors. Another approach is developing lower cost canopy temperature sensors. These sensors enable producers to monitor crop temperature stress, providing a more accurate indication of when irrigation is needed than relying solely on soil moisture sensors. The canopy temperature has been shown to be a reliable indicator of water needs for a crop while producers often rely on leaf appearance, such as curling, to indicate water needs. Research has shown that leaf curling is a mechanism which helps the plant cope with higher temperatures and does not correlate with the need for irrigation. The use of canopy temperature instead of leaf curling significantly reduces the amount of irrigation applied to crops such as corn, soybean, and cotton. This reduced irrigation saves producers the cost of pumping the irrigation water which in turn improves their economic return on the crop. Additional sensor developments have focused on the creation of a biodegradable sensor that attaches to the plant to allow for real-time monitoring of the plant stress and observing for disease. The current design of the sensor utilizes a biodegradable cellulose substrate, which breaks down at the end of the season and does not require removal before harvest. The use of cellulosic substrates on the sensor also prevents microplastics from being introduced into the environment. Future iterations of the sensor are being designed, which will derive their power from excess plant sugars, essentially powering the sensor from the crop that it is monitoring. Another sensor under development is designed to monitor water quality in aquaculture production. This sensor is mounted on a fish and can record water quality data, which is essential for maintaining the health of the fish and preserving the flavor profiles of the harvested fish. The data is recorded throughout the day as the fish moves around the pond and is transmitted when the fish approaches the surface to feed. Objective 2 focuses on irrigation scheduling. To help optimize irrigation scheduling for cropping systems, a method using multi-sensor capacitance probes was assessed for a third crop season and a fourth year of data collected. Four on-farm irrigation automation sites were evaluated this past year. Data was compiled on time used, irrigation amounts applied, and crop yields for both automated and non-automated sites for the fourth year. In addition, the data collected was used to build several hydrologic models to test the ability of current model frameworks to simulate automated irrigation. A range of irrigation scheduling methods, including those that integrate ground-based and remotely sensed data, were compared for the third year to help develop new and novel sensor systems and tools for water resource management as part of Objective 3. Combinations of tension-based irrigation triggers and nitrogen fertilizer rates are being continually evaluated in sprinkler-irrigated corn on two soil types to help researchers determine the water tension levels at which irrigation is recommended. Researchers also combined measurements from electrical resistance sensors and multisensory capacitance probes with aerial\satellite images to help create and evaluate an algorithm, allowing for the successful delivery of grid-based metrics that can be used to determine irrigation needs over a larger area. Three sprinkler irrigation systems and a tile drainage system were in operation to evaluate and improve current best management practices on irrigated fields. Cover crop studies have had three full winters of cover crops planted and four cash crop seasons. Soil, water, nutrient, and agronomic data have been collected for the cover crop studies, irrigation system studies, and tillage and fertilizer placement treatments. The evaluation and improvement of practices related to irrigation is Objective 4. Researchers in Stoneville and Starkville, Mississippi, developed a novel prototype farm implement that punches smooth precision holes in lay-flat irrigation tubing. Lay-flat irrigation tubing is used for over 75% of irrigated acreage in the Mississippi Delta. This method allows for more uniform application of irrigation water while significantly reducing labor during the installation of irrigation tubing. The prototype is estimated to save 100,000 to 250,000 gallons of water per irrigation on a typical 40-acre field in the Delta. This device has been tested on several research fields and is being evaluated in two on-farm demonstrations under commercial use. Objective 5 specifically focuses on engagement with stakeholders through our university research and extension partners. In support of this objective, 32 soil moisture sensor demonstrations were conducted in addition to the established four on-farm automation sites. An additional four farmers also participated in a new on-farm demonstration of wide-skip furrow irrigation, a technique that originated as a farmer innovation and has shown significant promise of saving pumping costs and reducing runoff. Meetings with and presentations to stakeholders were conducted, as well as the second iteration of the Master Irrigator program, which included 60 participants. An irrigation field day was held in the summer, with 58 producers and extension agents in attendance. Field tours and demonstrations were given, technical assistance on irrigation management was provided to farmers and extension agents, and a stakeholder-oriented annual report was compiled. The responses for the conservation practices survey questionnaire have been tabulated, and analyses are ongoing. An additional irrigation management choice survey was deployed with two iterations to the Master Irrigator participants. An experiment in cotton production systems has begun to develop and validate models using remote sensing and eddy covariance (EC) methods as part of Objective 6. EC towers are used to directly observe the exchanges of gas, energy, and water vapor between ecosystems and the atmosphere. EC stations for monitoring water and CO2 have been established on cotton fields in Texas and Mississippi with a focus on systems grown under different evapotranspiration conditions. Additionally, an investigation was conducted into the photosynthetic and chlorophyll fluorescence responses of peanut plants to light under elevated CO2 and temperature conditions. The chamber experiments have been completed, and the data have been collected, analyzed, and published.

Accomplishments
1. Automated hole insertion in lay flat irrigation tubing. Surface irrigation accounts for over 80% of the irrigation in the Lower Mississippi River Basin. The most common irrigation method distributes water through lay flat irrigation tubing in which holes are manually punched to allow water to flow into the furrows. Other investigators have previously developed computer programs to determine the size of the hole to be cut which allows for more uniform distribution of the water. However, the manual punching technique is labor intensive, results in distorted hole sizes due to material characteristics and human variability when using the manual punch, and allows for a limited number of hole sizes and positions. Researchers have developed a prototype automated hole punching system which punctures the hole in the pipe as the pipe is installed in the field. This results in labor savings and more precise hole sizing which has been demonstrated to save between 100,000 and 250,000 gallons of water per typical irrigation event.

2. High temperatures cause irrigators to over-apply in Mississippi Delta. Field level data from a voluntary water use reporting program in the Delta region of Mississippi showed that crop growers increase the amount of groundwater pumped for irrigation during periods of high air temperature. Regression analysis showed growers apply excess irrigation to cope with high temperature conditions, while evapotranspiration and precipitation during the growing season are not significant factors in the decision of how much irrigation to apply. The financial cost of mismanaging heat stress with excessive irrigation is estimated at a minimum of over $33 million per year. A manuscript showing this research received the award for “Publication with Most Impact on Mississippi” issued by The College of Agriculture and Life Sciences and the Mississippi Agricultural and Forestry Experiment Station.

3. Furrow irrigation spacing in vertisols– saving water & reducing costs. Furrow irrigation accounts for approximately 80% of the irrigation systems used in the Mississippi Delta. Furrow irrigation is generally viewed as inefficient due to runoff from rows closer to the water source which are completely wet out while farther rows are still filling. The heavy cracking clays (vertisols) which are prevalent in the Mississippi Delta can present an additional challenge in irrigation due to water filling cracks instead of moving down the rows. Research and on-farm studies have demonstrated that applying the same total volume of water to the field by concentrating the flow on fewer rows will irrigate these soils faster with less runoff. This irrigation technique utilizes undersurface movement of the water through the network of cracks in the soil. The soil profile fills from the bottom up instead of the top down. The lateral movement of water has been observed up to 4 rows away from the irrigated row. This technique allows for fully irrigating the field in less time, which reduces pumping costs, and with significantly reduced runoff. The use of soil moisture sensors allows the subsurface movement of the water to be monitored. Wide-scale implementation of this technique on vertisols will reduce energy costs while saving water.

4. Reduced water use and improved profitability from combined planting and irrigation strategies. Twin-row planting has become more common for soybean and corn production to increase yields, control weeds and improve resource utilization. Similarly, skip-row irrigation has been used in some areas for water conservation; however, there is the potential for yield reduction in high water demand crops. Researchers have conducted studies to integrate both practices into agronomic production systems in the Mississippi Delta. Studies have focused not only on yield and water-use but more importantly on the economics of the combined practices. Researchers have identified the conditions under which the combined practices lead to higher economic returns for producers while reducing irrigation water use. This is especially valuable in the humid Mississippi Delta where irrigation is supplemental.

5. Integration of agronomic practices to improve groundwater sustainability in humid growing regions. The Mississippi Delta receives significant annual rainfall, but the timing is often misaligned with the agricultural growing season. Research has demonstrated the benefits of improved irrigation water use efficiency by managing agricultural production as an integrated system incorporating tillage and cover practices alongside irrigation management decisions. Cover crops have been shown, in some conditions, to reduce runoff and improve irrigation water use efficiency without harming yields. Similarly, conditions have been identified in which no-till and reduced tillage practices are able to improve producer profitability while conserving water resources.

U.S. DEPARTMENT OF AGRICULTURE

Sustainable Water Management Research: Stoneville, MS