Agricultural Economics Department
irrigation, agricultural economics
Between 1969 and 1978, the irrigated area in South Dakota increased by over 2.3 times, a faster relative rate of development than that in any other Great Plains state, and second nationally only to that in Georgia. Nevertheless, South Dakota today ranks only 20th in the nation in its total irrigated acreage. The total irrigated area in South Dakota in 1979 was estimated to be about 450 thousand acres. About 80% of the total, or 377 thousand acres, involves land on which irrigation facilities have been developed by individuals and groups with private financing. In 1970, 45% of South Dakota's privately developed irrigated area was dependent on groundwater sources and 58% was dependent on surface water sources. During the 1970's, the pace of groundwater development for irrigation exceeded that for surface water. Thus, by 1979, the percentage of privately developed irrigated area relying on groundwater sources increased to 57%. Compared to other states, South Dakota is above average in the proportion of total irrigation withdrawals from groundwater sources, but below average in the proportion of on-farm pumped irrigation water from groundwater sources. Between 1969 and 1982, the total irrigation permit area in South Dakota increased from less than 0.5 million to over t.2 million acres. During this same period, the area actually irrigated, as a ratio to the irrigation permit area, showed a definite upward trend. Underlying the trend are changes in both the regulations surrounding the granting of permits and the perceptions of farmers concerning their applying for irrigation permits. The principal crop grown under irrigation in South Dakota (corn) covers about 1/2 of the total irrigated area in the state. Alfalfa ranks second. During the 1970's, the rate of increase in irrigated corn production slightly exceeded that for irrigated alfalfa (20 versus 16%/yr). In 1970, about 7% of the irrigation water distribution systems in South Dakota were center pivot machines. By 1982, this had increased to nearly 70%. Two factors underlying the rise of the center pivot are a relatively low labor requirement for center pivot water distribution and the fact that the period of accelerated irrigation development in the state occurred when the new center pivot technology had already become developed and was available on the market. About 80% of South Dakota's irrigated systems involve electric power (about 35% did in the early 1970's). An underlying reason for the shift toward electricity is a lower rate of escalation in the price of electricity than in the prices of competing energy sources during the 1970's.
Agricultural Experiment Station, South Dakota State University
Taylor, D. C., "South Dakota Irrigation Regional Shifts During the 1970's" (1984). Agricultural Experiment Station Circulars. 269.