Project : USDA ARS

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Research Project: Preserving Water Availability and Quality for Agriculture in the Lower Mississippi River Basin

Location: Delta Water Management Research

2018 Annual Report

Objectives
Objective 1: Measure, model, and/or estimate the impact of current and innovative farming practices on water quantity and quality while sustaining crop yields and reducing environmental impacts in irrigated agroecosystems. Sub-objective 1a: Quantify changes in irrigation water use, water quality, and crop water productivity as a result of implementing innovative rice production practices. Sub-objective 1b: Quantify changes in irrigation water use, water quality, and crop water productivity as a result of implementing innovative row-crop production practices. Objective 2: Develop and/or enhance agronomically sound irrigation and drainage management tools, practices, and technologies that protect and/or increase available water resources. Sub-objective-2a: Evaluate alternative sources of irrigation water. Sub-objective-2b: Evaluate practices and technologies for managed recharge of the MRVA aquifer. Objective 3: Improve watershed management in irrigated agroecosystems of the Lower Mississippi River Basin. Sub-objective 3a: Develop an improved understanding of nutrient and sediment transport, transformations and the hydrology in an irrigated landscape.

Approach
To preserve the quantity and quality of irrigation water supplies in the Lower Mississippi River Basin, it is necessary to consider the range of crops, soils, and production systems; the types of irrigation and drainage systems employed; the level of runoff water recycling employed; and the different water sources available. This project will address ways to improve the sustainability of groundwater supplies by investigating alternative irrigation methods for the crops currently produced in the region. Production system evaluations will include on-farm research with active participation by crop producers and crop advisors. Data collected from on-farm evaluations will be used to inform, enhance and validate existing hydrology models. Findings from this research are expected to reduce agricultural reliance on groundwater and improve water resources management, inform decision makers of potential impacts of conservation practices, and arm producers with tools and technologies that conserve water resources while maintaining crop yield.

Progress Report
The Delta Water Management Research Unit has had a productive fourth full year. The mission of the unit is to execute research related to agricultural water resources management at the plot, field, farm and watershed scales to further our knowledge base, evaluate technological solutions and inform crop production practices. Much work is at the farm and field scale, which requires collaboration with regional producers, organizations and universities (Arkansas State University (ASU), University of Arkansas, and Mississippi State University). Through collaboration and base and grant funds, the program supports 3 researchers, 2 support researchers, 1 program support assistant, and 5 seasonal limited appointment(LA) employees. Through collaborative agreements the unit works with 1 post-doctoral researcher, 2 ORISE researchers, 2 full-time technicians, and several summer technicians-both undergraduate and high school students. The three unit ARS researchers were part of small groups that won the 2018 Rice Technical Working Group (RTWG) Distinguished Rice Research and/or Education Team Award for "Advancing irrigation management practices to achieve sustainable intensification outcomes” and the 2018 Educational Aids Blue Ribbon Competition for “Innovation in Rice Irrigation Will Help Reduce Aquifer Decline”. Direct grant funding was successfully secured through the Arkansas Cotton Board, Arkansas Rice Research and Promotion Board, Cotton Inc., Ducks Unlimited, Kelloggs, and the Natural Resources Conservation Service. Collaboratively the unit has received sub-awards from two Arkansas Soybean Research and Promotion Board grants. The ARS scientists were invited to present at RTWG Meeting, Arkansas Soil and Water Education Conference, 4th Americas sub-Group of the Paddy Rice Global Research Alliance (via video conference), and the Cotton and Rice Production Conference. The ARS researchers mentored three students in the Bridge the Divide Program. An ARS scientist was invited to Uruguay and Paraguay (all expenses paid) to present on irrigation innovation in rice production. All researchers are developing their individual programs while working collectively on unit-wide efforts. Continued progress was made on groundwater/surface water interaction, in-stream water quantity and quality, and water quality of reservoir and tail water recovery irrigation systems. In close collaboration with a local producer, the ARS researchers are measuring water use, water quality, greenhouse gas emissions, soil moisture, grain quality, and/or arsenic levels from 16 production sized rice fields (four irrigation treatments replicated four times) for the second year. Largely from newly funded research grants in collaboration with ASU, an ARS researcher has begun a new study on irrigation impacts from cover crop use in soybean and cotton production. Through collaboration with RiceTec, Dale Bumpers National Rice Research Center, and ASU, an ARS scientist continues to build upon a database of greenhouse gas emissions by management and variety from the mid-south. An ARS researcher recruited one foreign national PhD student and one foreign national research associate to conduct study on field phenomics of 300+ rice accessions under high nighttime air temperature which is part of a multi-institutional National Science Foundation project on rice and wheat heat resilience.

Accomplishments
1. Development of greenhouse gas emission factors based on crop and water management practices in the U.S. will improve the Rice Fieldprint calculator for the estimates of greenhouse gas inventories from U.S. rice systems. Current guidelines to estimate total greenhouse gas from rice systems and to identify factors influencing magnitude of emissions have been focused on research from Asia. However, U.S. rice production practices are different from Asian rice management thus existing emission factors may not be applicable to U.S. greenhouse gas emission inventories. ARS researchers at Jonesboro, Arkansas, and the Rice Methane Science Group worked together to analyze existing data from the U.S. and develop an emission calculator for the estimates of total nitrous oxide and methane emissions from U.S. rice cropping. This analysis can be used towards the development of tools to estimate greenhouse gas emissions from U.S. rice systems and other similarly mechanized systems in Europe, South America, and Asia. This information is very important to national and international scientific working groups on greenhouse gas inventories and importantly rice growers on trading of carbon emissions to Carbon Credit Marketplace.

2. Simulated irrigation with historic weather showed benefit from irrigation innovation in rice. Rice is an important crop grown in the Lower Mississippi River Valley. However, rice currently receives up to three times the amount of irrigation applied to soybean, cotton, and corn. Because the primary source of irrigation in the Lower Mississippi River, the Mississippi River Valley alluvial aquifer, is declining, there are on-going efforts to devise best management practices that reduce irrigation use. Multiple-inlet rice irrigation uses plastic tubing to simultaneously deliver irrigation to all paddies of a rice field. This can reduce irrigation use by up to 25% compared to the standard practice of cascade flooding. The research of ARS researchers at Jonesboro, Arkansas, demonstrates that the irrigation savings achieved when using Multiple-inlet rice irrigation depend heavily on a farmer’s management style. Even without rainfall, multiple-inlet rice irrigation was found to reduce irrigation use by 22%, relative to cascade flooding, when irrigation was promptly halted as soon as runoff occurred from a rice field. These results show that multiple-inlet rice irrigation saves water through a combination of improved application efficiency and rainfall capture. The contributions of both application efficiency and rainfall capture depend on the proper use and management of multiple-inlet rice irrigation by the producer.

3. Identified potential solutions to improve irrigation management that will impact the longevity of the Mississippi River Valley Alluvial Aquifer and production agriculture in the Lower Mississippi River Basin. Arkansas irrigates the third most land area of any state in the U.S. with approximately 80% of irrigation water coming from the Mississippi River Valley Alluvial Aquifer. The Lower Mississippi River Basin grows approximately 75% of U.S. rice, so how rice is irrigated impacts the region. Field scale analysis of data from over 10 years found improved irrigation education was required to achieve the full extent of quoted benefits. ARS researchers at Jonesboro, Arkansas, along with collaborators, provided a synthesis of the Mississippi River Valley Alluvial Aquifer and described active research areas that may provide potential solutions to aquifer declines. The research areas described include irrigation, managed aquifer recharge, and the use of on-farm irrigation reservoirs. On-farm irrigation reservoirs and associated structures have been constructed to help reduce reliance on groundwater but are understudied. An inventory of these reservoirs was completed for two major regions of the state identified as critical groundwater regions.

4. Demonstrated nutrient reduction in field runoff from conservation practices at the plot and field-scale from commercial farms will lead to more sustainable cotton systems. Nutrient and sediment rich runoff contributes to the hypoxic zone in the Gulf of Mexico and is a loss to producers. Water quality measurements of surface runoff highlight the minimal impact of conservation furrow tillage and nitrogen fertilization practices on nutrient transport in irrigated cotton production at the plot scale. Water quality metrics such as pH, electrical conductivity, hardness, total suspended solids and soil sediment concentrations were within acceptable ranges and expected to have minimal impacts on surrounding waterbodies. Research results from ARS researchers at Jonesboro, Arkansas, support the adoption of conservation practices that minimize nutrient losses in furrow irrigation systems. Ten edge-of-field sites were established to quantify the impact of conservation practices on water quality on large production farms within Mississippi River Basin Healthy Watersheds Initiative project areas and Critical Groundwater Area. Findings illustrated nutrient reduction in these large study fields with cover crops compared to those without and the potential for non-growing period management to influence nutrient losses. Improved management in cotton will make a more resilient cotton production system for both producers and the environment.

U.S. DEPARTMENT OF AGRICULTURE

Delta Water Management Research: Jonesboro, AR