|Evett, Steven - Steve|
|HOWELL, TERRY - Retired ARS Employee|
|SCHNEIDER, ARLAND - Retired ARS Employee|
|DUSEK, DON - Retired ARS Employee|
|Brauer, David - Dave|
|MAREK, THOMAS - Texas Agrilife Research|
Submitted to: Transactions of the ASABE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/20/2015
Publication Date: 2/23/2016
Publication URL: https://handle.nal.usda.gov/10113/61944
Citation: Evett, S.R., Howell, T.A., Schneider, A.D., Copeland, K.S., Dusek, D.A., Tolk, J.A., Brauer, D.K., Marek, G.W., Marek, T.M., Gowda, P. 2016. The Bushland weighing lysimeters: A quarter century of crop ET investigations to advance sustainable irrigation. Transactions of the ASABE. 58(5):13031/trans.58.11159.
Interpretive Summary: Irrigation produces >40% of agricultural products and the majority of high value agricultural products in the USA on 20% of the cultivated land. But irrigation uses about 70% of national freshwater consumption. The economic and strategic importance of the agricultural production that depends on irrigation cannot be overstated. Yet, increasing competition for freshwater and impacts of climate change are putting pressure on water supplies and on irrigation. There are three major ways in which irrigation water use efficiency can be increased, thus reducing the amount of water needed to produce a given harvest. One way is to reduce over irrigation. This saves water, reduces pumping costs, saves fertilizer and reduces pollution. And it often increases yields since too much irrigation leaches out valuable nutrients and can drown a crop. A second way is to reduce under irrigation. Mistakes in irrigation that leave a crop without sufficient water during critical growth stages can greatly reduce yield and harvest quality. A third way is to irrigate more when it is important for the crop to be well watered in order to flower and grow the plant parts that are harvested, and to irrigate less when doing so will not much affect yield and quality. A fourth way is to use an irrigation application system that more evenly applies water, places the water where and when the plants need it, and reduces unnecessary losses due to evaporation. These four keys to efficient agricultural irrigation water use require knowledge of crop water use and yield relationships as influenced by weather, crop choice, irrigation system choice and management, and agronomic practices. The four keys to efficient water use were the subject of intense study for more than 25 years at the USDA-ARS Conservation & Production Research Laboratory since the research team there constructed large weighing lysimeters to accurately measure crop water use in irrigated fields. These studies advanced the cause of sustainable irrigation by increasing knowledge of crop water use and yield as affected by management, improving the tools used to measure crop water use and providing the tools for farmers to manage irrigation using the four keys to maximize water use efficiency
Technical Abstract: In 1987-1989, the first irrigated crops were grown on the four large, precision weighing lysimeters at the USDA-ARS Conservation & Production Laboratory on the Southern High Plains (SHP) at Bushland, Texas. Thus began >25-years of full- and deficit-irrigated crop growth, energy and water balance, evapotranspiration (ET), yield and water use efficiency (WUE) studies of major SHP crops, including alfalfa (Medicago sativa, L.), corn (Zea mays L.) and sorghum [Sorghum bicolor (L.) Moench] for both grain and forage, cotton (Gossypium hirsutum L.), soybean (Glycine max L.), sunflower (Helianthus annuus L.) and winter wheat (Triticum aestivum L.). Alfalfa was studied to support development of the ASCE Standardized Reference ET methodology. The lysimeter effort, led by Terry Howell, Sr., co-designed with Lynne Ebling and Thomas Marek and constructed by Arland Scheider, eventually grew to include a separate lysimeter to study grass ET, again for the ASCE standard, and a 48-lysimeter facility to study the important effect of soil type on crop water uptake, ET and WUE. That facility includes 12 lysimeters each of four soils covering the range of irrigated soils of the SHP. The large lysimeters were managed to be representative of sprinkler-irrigated fields so as to develop knowledge of crop coefficient (Kc) functions used for irrigation scheduling by many clients of ET networks developed by Texas A&M AgriLife teaming with ARS. The lysimeters have been used to test and further develop several technologies important to irrigation science, including soil water sensors, eddy covariance and Bowen ratio systems, infrared and laser scintillometers, thermal remote sensing based ET models, and hydrologic and crop simulation models. With the installation of subsurface drip irrigation systems on two of the lysimeter fields in 2013, the Bushland lysimeters are entering a new phase of advanced irrigation method and management studies.