Browsing by Author "Stewart, J. I."
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Item Functions to Predict Optimal Irrigation Programs(1974) Stewart, J. I.; Hagan, M. R.; Pruitt, W. O.Irrigation requirements are sometimes estimated using methods which may tend both to the overdesign of irrigation systems with associated higher investment costs, and to over irrigation. When the latter occurs, water, energy, and labor are wasted and other problems are created, often including reduced crop production. Going one step further, irrigation agronomists and economists have long been aware that profit may be maximized below the maximum crop yield point (Le., where some slight water deficiency is incurred), and this becomes more probable as water cost rises (8). The research reported strengthens these earlier findings and indicates that maximum water-use efficiency (i.e., production per unit of water) often occurs at irrigation levels slight lower than the maximum profit point.Item Irrigating Corn and Grain Sorghum with a Deficient Water Supply(1975) Stewart, J. I.; Misra, R. D.; Pruitt, W. O.; Hagan, M. R.Today as in the past, the great majority of farmers operate at the poles of the irrigation spectrum. Either they irrigate generously to insure against crop yield losses due to water deficits, or they do not irrigate at all. Both positions are honourably rooted in the history of water availability and in water and product prices.Item Research on Crop Water Use and Drought Responses in East Africa(International Crops Research Institute for the Semi-Arid Tropics., 1978) Stewart, J. I.; Wangati, J.; Fred, J.; USAID/USDA/KARI Research Project; Kenya Agricultural Research InstituteUntil the early 50’s, the main effort in agricultural production and hence agricultural research in East Africa was devoted to industrial crops like coffee, tea, cotton and sisal. Tea presented no problems being grown on the fertile well-watered highlands. Most coffee estates were also located in areas of sufficient rainfall and similarly the low land areas with high convective rainfall proved appropriate for cotton. For those expatriate farmers who could not get into the highlands, sisal proved well adapted to the drier savannah regions. For these individual crops, therefore, the major limiting factors were diseases and maintenance of soil fertility.
