I N humid regions, the question of whether one should irrigate often overshadows problems such as selecting the proper system or scheduling procedure. To show whether it pays to irrigate by running irrigation experiments in the field is a long, expensive process. It would take perhaps five to ten years to determine significant relationships. The approach used in this project was to set up a computer model relating crop yields to weather data and moisture stress, and then verify the model at a

more »

... w points using field experiments. This first report on the project includes only the field procedures and yields. A few well-controlled experiments have been run in the Northeast to find the crop response to irrigation, for example, Vittum, et al. (1963), and Ross et al, (1979) . Generally, they do not provide the specific weather and soils data necessary to determine the parameters in the computer model. Powell et al., (1981) have tests underway that should eventually help verify the program. The trickle irrigation system is a very convenient tool for irrigation experiments. Small areas can be used for test plots with distinct lines between irrigated and nonirrigated plants; the plots are easily randomized for statistical purposes. The trickle system offers excellent control of moisture levels, is easily automated, and does not obstruct field operations. It was thus a logical and convenient choice for the system to use in this project. FIELD EXPERIMENTS Several irrigation experiments were set up in the 1979, 1980, and 1981 growing seasons at the Horticulture Farm at the University's Rock Springs Agricultural Research Center. Five horticultural crops (strawberries, raspberries, potatoes, apples, and cantaloupes) were planted, with irrigated versus non-irrigated treatments being the main point of interest. Potato Field Experiments A 0.4 ha plot was used for the potatoes with 24 blocks set out in a randomized complete block design of six treatments and four replications. Each block contained six rows, 9.1 m long and spaced 0.9 m apart. The variety was Norchip and the plants were spaced 20 cm apart in the row. There were four trickle irrigation treatments Article has been reviewed and approved for publication by the Soil and Water Div. of ASAE.