Irrigation and Climate

Abstract

The Great Plains have been transformed in the last three decades. From the dust-bowl days of the 1930's, the plains area has become, in the decades since, the scene of vigorous and successful agriculture. There are many reasons. The drought ended. Wartime demands for food stimulated rehabilitation. Innovations in machinery made farming more efficient. New methods of tillage helped anchor the soil and reduce erosion. Farm ponds were built and dozens of flood-control reservoirs were constructed. Two hundred million trees were planted; half of them are growing today. Drought-resistant crops like milo and new legumes were planted. But a list of the most important changes must include irrigation. Crops in vast semiarid regions of Nebraska, western Kansas, the Oklahoma panhandle and northwestern Texas, once subject to the vicissitudes of a highly fickle rainfall pattern, are now regularly nourished with water pumped from abundant underground reserves. The growth of irrigation has been profound. In the Texas panhandle, where little more than 20 years ago irrigation was practically nonexistent, 5 million acres covering 7,800 square miles are now under irrigation. One area of 8,000 square miles is 50 percent irrigated. Two adjacent counties embracing 1,860 square miles are more than 70 percent under irrigation. In Oklahoma, irrigated acreage has increased twelvefold since 1947. In Kansas it has increased thirteenfold in the same period, and in Nebraska it has increased tenfold since 1930. All of this water does more than soak into the ground. In the intimate mix of air, earth and water that determines climate some long-range effects might be anticipated. And there might already have been such an effect: a change in Great Plains climate. At least the suggestion is being put forth, though with appropriate tentativeness. last 13 yrs. vs. pre-1956 | lol % of Total Area 3as percentage of base.M_.. Area averages underlined. Station records, parentheses.