2007 Annual Report
1a.Objectives (from AD-416)
Determine methods for improved quantification of evapotranspiration (ET) and crop coefficients under all constraints in order to improve irrigation scheduling and water use efficiency. Develop remote sensing technologies and tools designed for improved prediction of crop water use and water stress at field and watershed spatial scales. Develop, test, and implement feedback systems for spatially and temporally variable irrigation application of water and nutrients, and develop, test and implement improved sensors for soil water content and plant stress. Develop and validate remote sensing technologies and procedures to enhance spatially and temporally variable crop water status feedback systems for use in variable rate irrigation systems. Quantify and improve crop water use efficiency in dryland/irrigated cropping systems in relation to tillage, irrigation, and crop management practices.
1b.Approach (from AD-416)
Research approaches include determinations of crop water use by soil water balance techniques (weighing lysimeters and neutron scattering methods) in practically all experiments, which include variations in irrigation method (subsurface drip at several depths and spacings, sprinkler, and low energy precision application or LEPA), irrigation amount (full and two to three levels of deficit), tillage (no-tillage, conventional, strip till, etc.), and/or crop and crop rotation, including rotation between irrigated and dryland cropping. Automatic irrigation systems based on sensing of crop status are designed/engineered and tested for ability to control crop water use efficiency and yield, thus reducing management expense (time and effort) while allowing management to control irrigation for best profitability and optimum water use. Key in this effort is evaluation and design of new crop and soil water status sensors. Remote sensing approaches to water use prediction are expected to improve energy balance modeling methods to make them useful for managers at farm, irrigation project, and watershed scales, and for policy makers.
This new CRIS project began on January 10, 2007. Major infrastructure improvements were completed with the replacement of one 3-span center pivot irrigation system and purchase and installation of a new 6-span center pivot irrigation system and associated pipelines, reservoir intakes, valves, pumps, and electrical power supply. Research on irrigation automation was continued using the old irrigation system and began using the new irrigation system in the 2007 cotton cropping season.
Part of this research was conducted under subordinate project 6209-13000-012-03R, which entailed cooperative research with an Israeli team to develop relationships between crop water stress and leaf reflectance in several colors, including the invisible thermal infrared. A strong relationship was found between a thermal index of water stress that is successfully used in irrigation scheduling and an index based on measurements of three colors in the visible range, which are easier and less expensive to measure than the thermal index. In the corn silage and forage sorghum evapotranspiration (ET) experiment, corn was replanted after an unknown virus or disease affected several plants on the weighing lysimeter. A shorter maturity corn hybrid was used to permit maturity for silage. Forage sorghum was produced, but a direct comparison between corn silage and sorghum silage in 2006 was not valid. Work on germination problems with subsurface drip irrigation continued using corn as the test crop. Work on comparisons of irrigation applications systems and their effect on seed bed soil water content and temperature during germination also continued with cotton as the test crop, again showing some differences in seed bed temperature and water content due to different application methods (drip versus spray irrigation for example). This has implications for early season growth of cotton, which is sensitive to soil temperature. Research on water use and productivity of sunflower was delayed by one year to repeat the cotton irrigation scheduling/water use efficiency study due to problems with data from the previous year. The water use efficiency (WUE) study on sunflower will begin in 2008. Except for the latter delay, the 2007 season was started as planned and is progressing well.
Under the subordinate project number 6209-13000-012-04S, the new Texas High Plains Evapotranspiration Network (TXHPET) (http://txhighplainset.tamu.edu) system and automated mailing list server delivered advanced, updated, standardized, precision irrigation scheduling data and associated meteorological data to producers, irrigation districts, university and ARS researchers daily as the number of weather stations grew to 19. Cooperative efforts are underway on projects, including county and regional ET mapping, evaluation of precipitation probabilities for county crop irrigation demand estimates, and irrigation consequences derived from the demand estimation model. More details on the two subordinate projects are found in their reports, including documentation of monitoring activities to ensure project performance.
NEW IRRIGATION SCHEDULING NETWORK FOR THE TEXAS HIGH PLAINS:
Profitability of irrigated agriculture in the High Plains is constrained by high pumping costs and by the loss of nutrients and water due to over irrigation, resulting in decreased yields and increased expenses. Scientists in the Soil and Water Management Research Unit, Bushland, Texas, collaborated with the Texas Agricultural Experiment Station to create the new Texas High Plains Evapotranspiration Network (TXHPET) and automated mailing list server, which delivered advanced, updated, standardized, precision irrigation scheduling data and associated meteorological data to producers, irrigation districts, and university and ARS researchers daily as the number of weather stations grew to 19 (http://txhighplainset.tamu.edu). Savings in pumping costs, if irrigation is reduced by only one inch, translate to more than $12 million in the irrigated Texas High Plains; and increased profits of many more millions of dollars are expected from increased yields reported by cotton and corn producers using the network. (NP201, Problem Area 2, Irrigation Water Management)
COMPUTERIZED CENTER PIVOT IRRIGATION SYSTEM REDUCES MANAGEMENT TIME/INCREASES WATER USE EFFICIENCY:
Profitability of irrigated agriculture in the High Plains is constrained by high pumping costs and by the loss of nutrients and water due to over irrigation, resulting in decreased yields and increased expenses, yet producers have limited time to manage irrigations. Scientists in the Soil and Water Management Research Unit, Bushland, Texas, created a supervisory control and data acquisition (SCADA) system to read crop leaf temperatures remotely using infrared thermometers, and to control a center pivot irrigation system to apply water automatically using the time-temperature threshold (TTT) method of automatic irrigation scheduling. The SCADA system has been shown to produce high yields while using water efficiently, reducing management effort, and eliminating over irrigation. (NP201, Problem Area 2, Irrigation Water Management)
|Number of active CRADAs and MTAs||1|
|Number of web sites managed||3|
|Number of non-peer reviewed presentations and proceedings||34|
|Number of newspaper articles and other presentations for non-science audiences||4|
Allen, R.G., Walter, I.A., Elliott, R.L., Howell, T.A., Itenfisu, D., Jensen, M.E., Snyder, R.L. 2005. The ASCE standardized reference evapotranspiration equation. Reston, VA:American Society of Civil Engineers. 59 p.
Evett, S.R., Ruthardt, B.B., Copeland, K.S. 2006. External full-time vacuum lysimeter drainage system. Applied Engineering in Agriculture. 22(6):875-880.
Tolk, J.A., Evett, S.R., Howell, T.A. 2006. Advection influences on evapotranspiration of alfalfa in a semiarid environment. Agronomy Journal. 98:1646-1654.
Irmak, S., Payero, J.O., Martin, D.L., Irmak, A., Howell, T.A. 2006. Sensitivity analyses and sensitivity coefficients of standardized daily ASCE-Penman-Monteith equation. Journal of Irrigation and Drainage Engineering. 132(6):564-578.
Howell, T.A., Meron, M. 2006. Irrigation scheduling. In: Lamm, F.R., Ayars, J.E., Nakayama, F.S., editors. Microirrigation for Crop Production. Design, Operation, and Management. 1st edition. The Netherlands: Elsevier. p. 61-130.
Enciso-Medina, J., Colaizzi, P.D., Multer, W.L., Stichler, C.R. 2007. Cotton response to phosphorus fertigation using subsurface drip irrigation. Applied Engineering in Agriculture. 23(3):299-304.
Evett, S.R. 2007. Chapter 2: Soil water and monitoring technology. In: Lascano, R.J., Sojka, R.E., editors. Irrigation of Agricultural Crops, 2nd edition. American Society of Agronomy Monograph No. 30. Madison, WI:American Society of Agronomy. p. 25-84.
Peters, R.T., Evett, S.R. 2007. Spatial and temporal analysis of crop conditions using multiple canopy temperature maps created with center-pivot-mounted infrared thermometers. Transactions of the ASABE. 50(3):919-927.
Evett, S.R., Ibragimov, N., Kamilov, B., Esanbekov, Y., Sarimsakov, M., Shadmanov, J., Mirhashimov, R., Musaev, R., Radjabor, T., Muhammadiev, B. 2007. Neutron moisture meter calibration in six soils of Uzbekistan affected by carbonate accumulation. Vadose Zone Journal. 6:406-412.
Ibragimov, N., Evett, S.R., Esanbekov, Y., Kamilov, B.S., Mirzaev, L., Lamers, J. 2007. Water use efficiency of irrigated cotton in Uzbekistan under drip and furrow irrigation. Agricultural Water Management. 90(1-2):112-120.