Agriculture in Semi-Arid Environments by Anthony E. Hall

By Anthony E. Hall

The semi-arid zones of the realm are fragile ecosystems that are being sub­ stantially changed through the actions of mankind. expanding human populations have ended in higher calls for on semi-arid zones for supplying human susten­ ance and the chance that this can improve desertification is a grave obstacle. those zones are harsh habitats for people. The famines that resulted from drought throughout the overdue 1960's and the 1970's within the African Sahel illustrated the unreliability of current agricultural platforms during this quarter. huge fluctuations in ag­ ricultural creation have happened in semi-arid zones of Australia, North Ameri­ ca, and the Soviet Union because of periodic droughts, even if significant ag­ ricultural know-how has been dedicated to agricultural improvement in those zones. The problem to mankind is to control those diverse semi-arid zones in order that professional­ ductivity is elevated and stabilized, and environmental deterioration is reduced. Irrigation can be utilized to extend and stabilize agricultural creation in semi-arid zones as mentioned in quantity five of this sequence, Arid quarter Irrigation. the current quantity, Agriculture in Semi-Arid Environments, makes a speciality of dryland farming in semi-arid zones, and is proper to the big components of the realm the place rainfall is proscribing and the place water isn't on hand for irrigation. This quantity is designed to help agricultural improvement in those components and contains stories and analyses of obtainable info by means of scientists operating in Africa, Australia, and on the U ni­ versity of California.

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Lawton et al. (1976) reported that streams descending the eastern slope of the Sierra Nevada Mountains were diverted with dams and ditches in the spring to water crops of yellow nut-grass (Cyperus esculentus) and wild hyacinth (Dichelostemma pulchella). The tubers and corms of these species were important food items and formed the basis of a vegeculture system that was unique in North America. Other wild plants also benefited from the irrigation and grew on the areas overflowed by irrigation wastewater, but these were not of as great importance as those listed above.

During the flow, some water sank directly into the terrace soil and some was ponded behind terrace walls, later penetrating into the ground. The terraces were therefore ancient erosion and flood-control structures, and served to regulate the amount of water applied to fields. Wetting of the soils enabled the terraces to be put to agricultural use, and even today some Bedouins sow barley in the terraces after an early winter flood. These structures were commonly used in the Americas, where they are called check-dams, and will be discussed in a following section.

In years of crop failure, the Indians relied solely on hunting and gathering. On the Lower Gila agriculture was of less importance than on the Lower Colorado. The major floods on the Gila occurred in January and February, and planting was done immediately after the floodwaters subsided (Spier, 1933). A second crop was also sown in mid-summer. Although the data are not complete, it would appear that summer thunderstorms were important in providing water for this crop. 3 Owens Valley Paiute A hitherto little-known agricultural system of apparent indigenous origin and perhaps considerable antiquity existed in early historic time among the Paiute of Owens Valley, eastern California.

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