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Title: CROP WATER USE AND IRRIGATION SCHEDULING OF COTTON IN A HUMID GROWING ENVIRONMENT

Author
item Sassenrath, Gretchen
item PRINGLE, H. - DREC
item ALARCON-CALDERON, V. - MSU

Submitted to: American Society of Agronomy Meetings
Publication Type: Abstract Only
Publication Acceptance Date: 7/20/2003
Publication Date: 10/25/2003
Citation: Sassenrath Cole, G.F., Pringle, H.C., Alarcon-Calderon, V.J. 2003. Crop water use and irrigation scheduling of cotton in a humid growing environment. American Society of Agronomy Meetings. Session 12:9:00, p. 386.

Interpretive Summary: Increased reliance on supplemental irrigation in the Mid-South has pointed out the absence of reliable irrigation scheduling methods. While different irrigation scheduling systems have been used in arid production areas, little is known about the determination of crop water use and crop water needs in humid growing environments. One component that is needed for such a system is a reliable measuring system for detection of soil and crop water status. This report details efforts to determine the efficacy of remote sensing methods to detect crop water status in cotton under the humid growing conditions of the Mid-South. The remote sensing methods include reflectance measurements in the visible spectral ranges, and thermal emissions from the soil and crop canopy. A boom system has been designed and built to allow rapid scanning of the crop canopy. Various ancillary measurements contribute to the information about environmental conditions during the measurement interval. The measurement system is a component of a larger study exploring the development of irrigation scheduling for the Mid-South.

Technical Abstract: Presently, producers in the Mid-South have adopted no standard method to monitor soil moisture or crop water stress as a basis for irrigation scheduling. In order to maintain acceptable productivity levels in the region, irrigation is becoming increasingly important. This increased reliance on irrigation has contributed to a decline in the ground water, confounded by the common occurrence of early season surface flooding due to inadequate drainage. To better manage our water resources, we need accurate, easily deployable, and rapid detection methods for determination of available soil water and crop water status that integrate well with irrigation scheduling methods. We are exploring visible and thermal remote imagery in conjunction with ground-based measurements of soil moisture status for its potential for detecting the onset of water stress in cotton canopies. Integration of these detection methods into irrigation scheduling decision support tools is being explored. To allow rapid scanning of the test plots, a boom containing a camera, a spectroradiometer and an infrared thermometer was built and mounted on a four-wheeler. The sensors mounted on the boom are positioned at various heights in the test plots and repositioned easily for rapid scanning of the crop canopy. Concurrent measurements of insolation, air temperature and spatial position are taken, together with soil moisture status from ground-based measurements, and used to estimate crop water use.