Browsing by Author "Wood, R.A."
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Item Water Conservation by Fallowing In Semiarid Tropical East Africa(1958) Pereira, H.C.; Wood, R.A.; Brzostowski, H.W.; Hosegood, P.H.; East African Agriculture and Forestry Research Organization: Tanganyika Agricultural CorporationCrop yields and soil-moisture changes to 6-ft. depth were measured in two cycles of five 2-year groundnut rotations. Fallows kept bare, sown with protective grass cover, and allowed to regenerate volunteer weeds and grasses were compared with maize and with sorghum in alternate-year cropping with groundnuts. Soil moisture- tension changes were following by gypsum blocks and quantitative changes were measured by soil sampling Measurements were made of the root ranges at different growth stages of groundnuts, maize, sorghum, and teff; all lay within the 6-ft. depth. Annual rainfall totals for the four years of the experiments were 22, 8t, 13, 13 in. respectively. The volunteer cover removed all available water from 6 ft: and used more water than maize, sorghum, or groundnuts. Bare fallow conserved water and increased subsequent yields of groundnuts, but no fully satisfactory soil conservation measures were achieved. Protection of fallow by a heavy sowing of 'teff' grass provided efficient soil conservation and, with a seed-rate of 20 lb. of viable seed per acre, suppressed weeds and stored subsoil moisture. Groundnut yields of over 400 lb. kernels per acre were thus secured in a year of 8'5 in. total annual rainfall.Item Water requirements of irrigated maize in Nyasaland(1964) Munro, J.M.; Wood, R.A.; Empire cotton growing corporation and department of Agriculture, NyasalandChanges in soil moisture under an irrigated maize crop were studied in two consecutive seasons in the Lower River area of Nyasaland. Irrigation was based on open-pan evaporation; the recorded evaporation in inches was multiplied by a series of irrigation factors, and irrigation was applied to balance the calculated deficit in each case. Soil moisture changes were recorded by measuring the electrical resistance of gypsum units with a Bouyoucos meter. The minimum irrigation required to hold the resistance constant is then approximately equal to the loss of soil moisture. It is shown that the ratio of crop water requirement to open-pan evaporation was not constant throughout the growing season of the crop but rose sharply about the time of the emergence of the tassels. The same irrigation factors gave similar patterns of soil moisture use in both seasons, although the evaporation, and hence the irrigation water applied, was appreciably different. The importance of linking results of irrigation experiments and recommended irrigations with observed or calculated evaporation figures is discussed.
