1a. Objectives (from AD-416):
Objective 1: Evaluate and optimize production systems for irrigated cotton, corn, and rice to optimize WUE under variable weather conditions that are expected to become more variable with impacts of climate change while considering the constraints of timing for field operations, a limited growing season, and increasingly limited water supplies. 1a: Determine crop coefficient for sprinkler irrigated rice. 1b: Determine water/yield relationships for sprinkler-irrigated rice and cotton. 1c: Compare drought-tolerant corn hybrids to those currently grown. 1d: Develop database of water use variation among rice production systems. Objective 2: Evaluate the suitability of variable-rate center pivot irrigation for crop production on variable soils and in varying weather conditions to determine potential costs and benefits for producers. 2a: Determine the utility of soil apparent electrical conductivity (ECa) and topographic variables for defining management zones to develop prescriptions for VRI management. 2b: Determine the optimum irrigation schedule for rice under center pivot irrigation over a range of sand contents. Objective 3: Evaluate the quality of runoff from irrigated cropland to determine current and potential environmental risks and develop guidelines and BMPs to reduce impact of irrigated agriculture on water quality degradation. 3a: Determine nutrient content of runoff from surface drained land in the lower Mississippi River basin. 3b: Develop guidelines for fertigation for center pivots in humid and sub-humid regions. 3c: Determine greenhouse gas (GHG) emissions associated with different water management strategies for rice production and options for reducing. 3d: Develop a variable source N application system utilizing controlled release nitrogen (CRN) technology to reduce N losses in furrow irrigated cotton.
1b. Approach (from AD-416):
Evaluate and optimize production systems for irrigated cotton, corn, and rice to optimize WUE under variable weather conditions that are expected to become more variable with impacts of climate change while considering the constraints of timing for field operations, a limited growing season, and increasingly limited water supplies. Evaluate the suitability of variable-rate center pivot irrigation for crop production on variable soils and in varying weather conditions to determine potential costs and benefits for producers. Evaluate the quality of runoff from irrigated cropland to determine current and potential environmental risks and develop guidelines and BMPs to reduce impact of irrigated agriculture on water quality degradation.
3. Progress Report:
This report documents progress for Project Number 3622-13610-003-00D, which started in April 2012 and includes objectives from both Agricultural Research Service (ARS) and University of Missouri (MU) scientists. Under ARS leadership: (1) Determined from 2012 study comparing standard and drought-tolerant corn hybrids that the location was not acceptable, identified new field, and addressed drainage problems exposed during extremely wet spring; modified sensor suite adding new infrared thermometer and reflectance sensors requiring new data-collection program; built and field tested new sensor-mounting system and a smaller sensor suite used to collect data in corn study addressing fertility, plant population, and irrigation; and continued investigating impacts of land grading. Worked with collaborators at University of Arkansas and ARS to compile and analyze 10 years of on-farm rice water use data. (2) Converted diesel-powered variable rate irrigation (VRI) center pivot system to electricity and upgraded pumping plant, replacing existing diesel power unit and line-shaft turbine pump with submersible electric pump, variable frequency drive, and remote monitoring and control system. Sensors for monitoring electric power were obtained to supplement sensors for pressure, flow, and depth-to-water. (3) Maintained runoff samplers and collected continuous stage and flow information from three southeast Missouri sites. Determined that more stable site was needed for Ditch 42, identified suitable site, moved and secured equipment, and installed fix to address rodent chewing on sampling tubes. Through a specific cooperative agreement with MU (see also 3622-13610-003-01S): (1) Initiated test using VRI to evaluate irrigation treatments for center pivot irrigated rice and cotton based on evapotranspiration calculated from on-site weather station data. Center pivot with VRI technology was evaluated for application uniformity within and between adjacent zones and zonal application depth when changing application percentages; findings were reported in poster presentation and corresponding proceedings article for 2013 American Society of Agricultural and Biological Engineers (ASABE) Annual International Meeting. (2) Cotton measurements of spatially referenced canopy properties continued in ongoing studies. Results from three year study were compiled and analyzed and findings were presented in oral presentation and corresponding proceedings article for 2013 ASABE International Meeting. The article is being expanded for submission to Applied Engineering in Agriculture. (5) On-farm studies were conducted to evaluate effectiveness of controlled release nitrogen (CRN) fertilizers relative to traditional nitrogen programs for furrow irrigated cotton. Additional study compares nitrogen content in runoff water between urea- and CRN- fertilized cotton plots. (6) Fifteen years of data from annual Bootheel Irrigation Survey indicated fertigation increased corn yield by 12 kg/ha. Related studies evaluated model to calculate crop coefficient values from local weather files; and indicated average 15 kg/ha yield increase when corn followed soybeans.
1. Demonstrated feasibility of rice production using center pivot irrigation. Traditional US rice production practices include maintaining flooded conditions for much of the growing season and many areas in the US Mid-South and throughout the world are not well suited for flooded production. Center pivot irrigation offers an alternative production system on high-infiltration soils, but little research exists on irrigation management for non-flooded production. Along with colleagues from the University of Missouri, ARS scientists at Portageville, Missouri demonstrated that commonly grown Mid-South rice cultivars could be produced on coarse-textured soil using center pivot irrigation and achieve grain yields comparable to flooded production. A method for scheduling rice irrigation was also developed and tested. Rice is a major component of the diet throughout the world and these results will assist producers to optimally manage irrigation when rice is produced with center pivot irrigation to reduce the water requirements on coarse-textured soils. Publication supporting this accomplishment: 274118
2. Documented increases in Mid-South irrigated area highlight need for combined state and federal response. Much of the USA was seriously affected by the 2012 drought, including the 4-million-acre irrigated area in the Mid-South where irrigated acreage continues to increase even though annual precipitation is high compared to other irrigated areas. Because of low water holding capacities and root-limiting soil layers, irrigation management is difficult and appropriate methods are not well identified or understood. Water quality and efficiency impacts under irrigation are also poorly understood. ARS scientists at Portageville, Missouri, and Bushland, Texas, used the Census of Agriculture, other published sources, and interviews in the region to document the increase in irrigation and the concurrent decrease in personnel addressing the problem. They called for a combined state and federal response to provide appropriate and effective problem solutions while ensuring efficient water use, high crop water productivity, and protection of water supplies and the environment. This information will be very helpful for state and federal policy makers and administrators charged with setting budget priorities under the current fiscal conditions. Publication supporting this accomplishment: 287394Oliveira, L.F., Scharf, P.C., Vories, E.D., Drummond, S.T., Dunn, D.J., Stevens, W.E., Bronson, K.F., Benson, N.R., Hubbard, V.C., Jones, A.S. 2013. Calibrating canopy reflectance sensors to predict optimal mid-season nitrogen rate for cotton. Soil Science Society of America Journal. 77(1):173-183. DOI: 10.2136/sssaj2012.0154.