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United States Department of Agriculture

Agricultural Research Service


Location: Cropping Systems and Water Quality Research

2010 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 described in Project Plan that include objectives from both ARS and University of Missouri scientists. Under ARS leadership: 1. In conjunction with multiple Natural Resources Conservation Service (NRCS) programs, additional pumping plants and irrigation reservoirs on Arkansas rice farms were monitored; systems were added as possible, including many in northeast Arkansas in cooperation with farmer who had participated in earlier phase of the project; work continued with a private company to find or develop wireless sensors to alert the producer when water levels in paddies were low or full that were capable of operating in extreme agricultural environments. 2. Worked with center pivot manufacturer to test prototype variable rate irrigation system. 3. Worked with other government agencies to assist groups wishing to participate in Mississippi River Basin Initiative projects and coordinate with project water quality activities within Little River Ditches watershed. Through the Specific Cooperative Agreement with the University of Missouri Delta Center (see also 3622-13610-002-01S, Improving Irrigated Crop Production in Southeast Missouri): 1. Used 152-m pivot to incorporate variability into irrigation management. Soil maps, soil textural field samples, and aerial photos were used to divide the field into specific irrigation treatments for corn and rice. Adapted study to allow spatially referenced yield data. 2. Studies addressed twin-row production of corn, cotton, and soybean on silty soils. Names of area farmers purchasinig twin-row planters were obtained for surveying. 3. Compared irrigation recommendations based on three automated sensor systems to irrigation scheduling software and updated website listing telemetry-based soil moisture sensor systems. 4. Installed dataloggers and sensors to measure operating characteristics on electric, open discharge wells. 5. Used system developed for real-time differentiation between nutrient and drought stress to monitor cotton and soybean studies. 6. Completed efforts to screen commercial cotton varieties and observed differences in tolerance to waterlogging. 7. Tested experimental crop coefficient function developed for computerized irrigation scheduling program adapted to accommodate rice, and installed sensors for monitoring soil moisture in a combination of small plot and large block rice studies under center pivot irrigation. Yields from large blocks will be spatially referenced.

4. Accomplishments
1. Variable Rate Irrigation Management: Soils in the U.S. Mid-South vary spatially due to a combination of alluvial, wind, and seismic activities. Traditional irrigation systems apply water at the same rate over an entire field, whereas site-specific irrigation allows precise amounts of water to be applied where and when plants need them for optimal growth. ARS researchers conducted an experiment in Florence, South Carolina, to evaluate spatial management of corn using a center pivot irrigation system modified to make site-specific applications of water and fertilizer. As expected, irrigation and nitrogen fertilizer increased corn grain yields, with yield increasing as nitrogen fertilizer increased in two of the three years. Regression analysis was used to evaluate the yield response to the combined fertilizer and water treatments, which differed between the rainfed-only and the irrigated treatments. These results will help in developing management strategies and decision support systems for profitable management of water and fertilizer on spatially variable soils commonly found in the southeastern and mid-southern U.S. while conserving natural resources and protecting the environment. Refereed Publication serving as basis for accomplishment: Log # 242733.

Review Publications
Stone, K.C., Camp Jr, C.R., Sadler, E.J., Evans, D.E., Millen, J.A. 2010. Corn yield response to nitrogen fertilizer and irrigation in the southeastern Coastal Plain. Applied Engineering in Agriculture. 26(3):429-438.

Last Modified: 2/23/2016
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