University of Missouri Extension

Background on Woodruff Method

Who's "Woody"?

Dr. C.M. "Woody" Woodruff is an emeritus professor with the Department of Agronomy at the University of Missouri. In the late 1960's, he developed a chart method to apply "adequate, but not excessive, water" in the form of irrigation. He is also know for the Woodruff buffer used in soil chemistry. Dr. Woodruff was one of the first researchers to break the 100-bushel per acre barrier on corn after WWII. The chart method in conjunction with other production practices, such as plant population and fertility management, was to assist farmers in maintaining top, potential yields.

Irrigators in the central part of Missouri adopted the charting practice in the 1970's and continue to use it today.

Historic Development of chart method

Woodruff charts are based on the original idea of Dr. "Woody" C.M. Woodruff, a professor emeritus at MU, who has worked in the Agronomy department there since 1929. He developed a chart method for timing irrigation back in the 1960's. The original chart was developed specifically for corn planted about May 1 and grown on claypan soils in central Missouri. The chart was developed into a fact sheet in the mid-1970's (Original MU Guidesheet on Woody method). Woodruff was originally as concerned with over-watering as he was with under-watering since the predominant soil had a clay pan at about one foot in depth that would slow percolation and induce water-logging.

Agricultural engineers Gregory and Schottman at the University of Missouri expanded the concept with a BASIC computer program that allowed historic weather data to become an input variable.1/ Also, additional crops, emergence dates, and soils could be utilized so that the program could be used at various locale/planting date combinations. The Kc values were developed from USDA/ARS water use studies in the Southwest which had used the Blaney-Criddle ET method.2/ A value of 80% of Blaney-Criddle evapo-transpiration was used as the reference value to reflect differences in Missouri conditions versus conditions in the Southwest. The Gregory-Schottman method did not construct a chart, but instead used a generated table.

In 1998 a spreadsheet version of the Woodruff Irrigation chart-maker was developed by Henggeler that allowed charts to be printed. This current web-based program is based on the software of Henggeler.3/

1/ Gregory, J.M. and R.W. Schottman. 1982. Irrigation scheduling procedure for subhumid areas. Transactions of ASAE. Vol (25) 4: 1290-1294.

2/ Erie, L.J., O.F. French, D.A. Bucks, and K. Harris. 1981. Consumptive use of water by major crops in the Southwestern United States. USDA Conservation Report No. 29. 42 pp.

3/ Henggeler, J. C. and P. E. Guinan. 2000. Missouri method of irrigation scheduling: the accumulative use chart. In. Proc. of the 4th Decennial National Irrigation Symposium, Nov. 14-16. Phoenix, AZ.

[ Contact Joe Henggeler for Questions/Comments ]
[ Woodruff Instructions and Background Information ] [ AgEBB ]