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United States Department of Agriculture

Agricultural Research Service


Location: Cropping Systems and Water Quality Research

2011 Annual Report

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
Efforts concentrated on continuing studies that include objectives from both Agricultural Research Service (ARS) and University of Missouri scientists. Under ARS leadership: 1. In conjunction with Natural Resources Conservation Service (NRCS) programs, pumping plants and irrigation reservoirs were monitored on Arkansas rice farms; continued work to find or develop wireless sensors capable of operating in agricultural environments to alert producers to water levels. 2. Worked with center pivot manufacturers to test variable rate irrigation systems. 3. Tested irrigation scheduling of large block cotton study. 4. Worked with NRCS to coordinate with Mississippi River Basin Initiative activities within Little River Ditches watershed. Selected three sites for monitoring and sampling runoff, installed samplers, and initiated data collection. Through Specific Cooperative Agreement (SCA) with the University of Missouri (see also 3622-13610-002-01S, Improving Irrigation Practices and Irrigated Crop Production in Southeast Missouri): (1) Used pivot to incorporate soil variability into irrigation management. (2) Measured spatially referenced canopy characteristics and air conditions above crop. (3) Compared twin- and single-row production of corn, cotton, and soybean. (4) Compared irrigation based on automated sensor systems to irrigation scheduling software. (5) Measured operating characteristics on electric, open-discharge wells. (6) Completed testing of adapted irrigation scheduling program for monitoring rice studies under center pivot irrigation. Through SCA with the University of Missouri (see also 3622-13610-002-02S, Improving Irrigation Management and Irrigated Crop Production in Southeast Missouri): (1) Tested irrigation scheduling of large block rice study. (2) Constructed system to develop rice crop coefficient. (2) Modified and tested sensor system so measurements can be made in undisturbed plots. (3) Constructed pyrolyzer and compared biochar conversion of a range of feedstocks. (4) Collected water samples from soil treated with biochar and used soil to test efficacy of insecticide. (5) Worked with two southeast Missouri producers on replicated large plot studies of controlled release nitrogen. (6) Compared conventional nitrogen lay-by application to four separate fertigations.

4. Accomplishments
1. Demonstrated less expensive substitute for soil sampling for root knot nematode in cotton. Root-knot nematodes (RKN) affect the root system of cotton, thereby impacting water and nutrient uptake. Farmers growing cotton need a reliable, accurate, and inexpensive method for mapping areas of potentially high risk from RKN within individual fields for site-specific application of nematicides. In cooperation with the University of Missouri and the University of Arkansas, and ARS scientists in Portageville, Missouri demonstrated that evaluation of post-harvest cotton roots for galling severity may be an alternative to soil analysis for nematodes for developing these maps. There was a significant negative correlation between root galling severity in October and cotton yield the next two years, indicating galling severity may be a useful indicator of the potential threat of RKN to crop performance for more than one year. The estimated costs for assessing galling severity were less than one-fourth those for soil analysis. Adoption of these procedures will benefit farmers by reducing their nematicide costs and will benefit everyone by identifying the precise areas where nematicides are needed and eliminating application to other areas.

2. Developed guidelines for seasonal termination of furrow irrigation on Mid-South cotton. A method was needed to help cotton farmers in the US Mid-South decide when to stop irrigating the crop. Stopping too soon resulted in lost yield, while late irrigations did not result in additional yield and complicated harvest. Regression analysis conducted by an ARS scientist in Portageville, Missouri was used with data from furrow irrigated Mid-South cotton fields conducting irrigation termination studies during the 2000 through 2007 growing seasons. While data from the southernmost fields proved too variable to serve as the basis for new guidelines, the resulting functions for the northern portion of the Mid-South were determined to be suitable for developing recommendations. The derived equations can be used to determine the timing of the last profitable irrigation for a known lint price and diesel cost, allowing the producer to react to his or her individual situation. These results will benefit farmers by eliminating the time and expense associated with unnecessary irrigation and everyone will benefit from the water that is conserved.

Review Publications
Wrather, J.A., Stevens, W.E., Vories, E.D., Kirkpatrick, T.L., Mueller, J.D., Mauromoustakos, A. 2010. The use of root gall ratings to determine high risk zones in cotton fields infested by Meloidogyne Incognita. Crop Science. 50(6):2575-2579.

Last Modified: 2/23/2016
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