1a. Objectives (from AD-416):
Objective 1: Develop methods and evaluate the benefits and limitations of site-specific management technologies for irrigated agriculture in the Mid-South region. Specifically, evaluate the suitability of variable-rate center pivot irrigation for crop production to on the variable soils and varied climatic conditions to determine potential costs and benefits for producers. Objective 2: Determine interactions between irrigation and agronomic practices, and identify cultivars/practices to overcome problems encountered in irrigated cotton and soybean production for the Mid-South region. Specifically, evaluate and optimize production systems for irrigated cotton, corn, and soybean to optimize WUE within timing constraints for field operations and limited growing season (for cotton) of the northern portion of the Mid-South. Objective 3: Determine the impacts of climate change on irrigated crop production and impacts on water quality in the Mid-South region. Specifically, evaluate and relate the quality of runoff from irrigated fields to determine current and potential environmental risks of sediment, nutrients, and/or pesticides leaving the fields.
1b. Approach (from AD-416):
To optimize irrigated crop production and protect soil and water resources in the Mid-South, it is necessary to consider natural soil variability within fields, the range of crops and production systems, and the types of irrigation systems employed. Our interdisciplinary team will address limitations to the overall goal of improving performance, profitability, and sustainability of Mid-South agriculture. We will investigate ways to improve irrigation scheduling and mechanized-irrigation-system management in spatially-variable soils. We will explore use of commercial sensors to provide information regarding crop water status and flood-water depth. Building on our previous research, we will investigate flood tolerance among cotton and soybean cultivars and plant introductions to reduce the risks associated with irrigating in humid climates; and investigate the water quality impacts of irrigated agriculture. We will investigate advantages and limitations to site-specific irrigation. Building on our long-term experience with irrigation scheduling, we will assess the options available for Mid-South irrigators. Site-specific irrigation and rice production system evaluations will include on-farm research with active participation by crop producers and crop advisors. Products of this research will include a sensor system for monitoring rice fields, water-conserving production systems for rice production, and improved flood tolerance for surface-irrigated Mid-South crops.
3. Progress Report:
Substantial results were obtained over the five years of this project, including 16 peer-reviewed publications. Site-specific management: Our research demonstrated the utility of variable rate irrigation in corn production. These results will help in developing strategies for profitable management of water and fertilizer on spatially variable soils commonly found in the southeastern and mid-southern US. We determined that root galling measurements could be a less-expensive substitute for soil sampling to determine the threat from root knot nematodes affecting cotton root systems and impacting water and nutrient uptake. These procedures will reduce costs by identifying the precise areas where nematicides are needed and eliminating application to other areas. Interactions between irrigation and agronomic practices: Our research demonstrated the viability of subsurface drip irrigation for Mid-South corn production. Some corn producing areas are experiencing water shortages and understanding irrigation options will allow producers to select the optimal production system. We evaluated irrigation scheduling for humid environments using infrared thermometer-measured canopy temperature. Canopy temperature has been successfully used in arid environments, but has been limited in humid areas. Irrigation water use efficiency was improved for corn and cotton by use of the IR technique. Irrigation is increasing in humid areas and this method shows potential to optimize water management and protect water supplies as demand for water increases. We quantified the effect of waterlogging on soybean growth. Surface irrigating soybean prior to a large rainfall, which can occur at any time during the Mid-South growing season, can reduce crop yield; a better understanding of yield loss due to waterlogging will result in best management practices to reduce the impact. We developed guidelines for termination of furrow irrigation for Mid-South cotton. Data collected from furrow irrigated Mid-South cotton fields can be used to determine the timing of the last profitable irrigation for a known lint price and diesel cost for the northern Mid-South. We investigated nitrogen (N) management for center pivot irrigated rice. Many areas in the world are not well suited for traditional rice production on continuously flooded soils and center pivot irrigation offers an alternative on high-infiltration soils, but little research exists on the optimum nitrogen management for non-flooded production systems. The results will allow producers to optimally manage nitrogen to reduce environmental impacts when rice is produced with center pivot irrigation. Impacts on water quality: Our research on site specific management and interactions between irrigation and agronomics all impacts the quantity and quality of runoff. In addition, we conducted sampling in southeast Missouri drainage ditches that will be greatly expanded in the new project.
1. Nitrogen management for center pivot irrigated rice. Many areas in the US Mid-South and all through the world are not well suited for traditional rice production on continuously flooded soils. Center pivot irrigation offers an alternative production system on high-infiltration soils, but little research exists on the optimum nitrogen (N) management for non-flooded production systems. Along with colleagues from the University of Missouri, ARS scientists at Portageville, Missouri, compared several scenarios and observed higher yields when more of the total N was applied as urea ammonium nitrate (UAN) in two of three years and that milled head rice was not affected by nitrogen management. Rice is a major component of the diet throughout the world and these results will allow producers to optimally manage nitrogen to reduce environmental impacts when rice is produced with center pivot irrigation.
2. Using canopy temperature for scheduling irrigation in humid areas. Infrared thermometers (IR) offer a convenient, non-contact method to measure crop canopy temperatures. Although canopy temperature has been successfully used for irrigation scheduling in arid environments, the technique has been limited in humid areas due to high humidity and intermittent cloud cover. Along with colleagues from the University of Missouri, ARS scientists at Columbia, Missouri evaluated an alternate scheduling method for humid environments using IR-measured canopy temperature. Although soybean and cotton yields were not significantly different across a range of irrigation treatments, irrigation water use efficiency, or the additional yield per unit of irrigation water, was improved for corn and cotton by use of the IR technique. Irrigation is increasing in humid areas and many climate change models predict more frequent droughts, which will lead to further increases. This method shows potential for irrigation scheduling in humid environments to optimize water management and protect water supplies as demand for water increases.
Vories, E.D., Greene, J.K., Teague, T.G., Stewart, J.H., Phipps, B.J., Pringle, H.C., Clawson, E.L., Hogan, R.J., O'Leary, P.F., Griffin, T.W. 2011. Determining the optimum timing for the final furrow irrigation on mid-south cotton. Applied Engineering in Agriculture. 27(5):737-745.