Browsing by Author "Pereira, H.C."
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Item Grass Establishment on Eroded Soil in A Semiarid African Reserve(1952) Pereira, H.C.; Beckley, V.R.S.An area typical of bare overgrazed land in the semi-arid Machakos African Land Unit has been used for experiments on restoration of fertility and on land management. A 32-acre factorial experiment on methods of grass esfaB1ishment is described. Sown and planted grasses were tested on land prepared by various cultivation treatments, and the first two years of grazing-yields are reported. Yields were substantially improved by ploughing, by manuring, and by the incorporation of manure in ridges. Ripping did not improve grass establishment or soil-moisture storage. In two drought years, 10·13 and 16.71 in. of rain respectively, the planting of grasses was more successful than sowing. In a year of very good rainfall sown grasses were rapidly established and gave yields equal to those of the planted species. Ridging was found to conserve available soil moisture for two months of dry weather. Grass roots increased the field capacity of the first 3 in. of soil, but did not, in 2 years, increase the volume of free-draining pore-space.Item Maintenance of fertility in dry coffee soils(1950) Pereira, H.C.; ; Coffee Research Station, Ruiru, KenyaThe application to tropical agriculture of practices well proven in temperate climates involves difficulties which are becoming recognized with greater clarity as the detailed conditions are investigated. One of the most difficult of these problems is that of the use of organic manures, a subject which must remain highly controversial until far more detailed scientific evidence on the conditions ruling in tropical soils can be obtained. The views advanced here are an interim interpretation of evidence which is, as yet, all too slender. They are therefore set out in order to promote thought and discussion on a subject most vital to East African agriculture.Item Part II-grazing Control In Semi-Arid Ranchland(1962) Pereira, H.C.Uganda is a well-watered territory in comparison with its East African neighbours, but in the extensive pastoral areas to the north of the Nile water shortage is often acute. Here the effects of a rather severe climate are exaggerated by overgrazing and misuse of land. Over many thousands of square miles, a rainfall of 20 to 30 inches per year which should be adequate for prosperous ranching enterprises, leaves a countryside parched and bare of keep, with men and cattle depending precariously on declining water-holes in the dry sandy torrent-courses.Item The Physical Effects of Contrasting Tillage Treatments over Thirty Consecutive Cultivation Seasons(1964) Pereira, H.C.; Dagg, M.; Hosegood, P.H.Measurements of the changes in the physical properties of topsoil are reported from a I5-year factorial tillage trial in a plantation of arabica coffee. Two monsoon-type rain seasons per year gave thirty cycles of soil wetting, weed growth, tillage, and soil drying. Rainfall acceptance tests showed clean weeding to cause an average IS per cent. Reduction of infiltration from very heavy rainstorms, compared with the minimum weeding treatment. Where a grass mulch provided coarse organic matter for incorporation into the topsoil, a modified rotary hoe, described in a previous paper, proved even more successful than hand implements in maintaining soil structure. In the absence of grass mulching, the rotary hoe did more damage than the hand implements. The experiments demonstrated a sound technique for maintaining very good topsoil structure; Part III of this series showed that these methods also increase yields.Item The Physical Importance of Forest Cover in the East African Highlands(1954) Pereira, H.C.; East African. Agriculture and Forestry Research OrganizationThe belief that the presence of large areas of forest may be the direct cause of local rainfall has been widely held since the close of the last century, when scientists, both in Germany and France, reported rainfall readings in forested areas to be higher than those measured in the immediately surrounding arable countryside. With the advance of our knowledge of meteorology, and of the techniques of rainfall measurement, it has become apparent that such effects need very largescale experimental studies with adequate statistical planning.Item Practical Aspects of Field Experimentation in Africa(1960) Pereira, H.C.; Vernon, A.J.; East African Agriculture and Forestry Research Organization, Muguga; Rothamshed Experimental Station Harpanden, HartsThis is a brief survey of some of the points properly written up, fully reported and which most need attention in field experimented data filed in station archives or central mental work under African conditions, where libraries. Many experiments are carried out by isolated an exploratory approach is needed for officers who have little chance of discussion practical investigations, whether they stem with technical colleagues. Many of the points from fundamental work or have begun on appear quite obvious when listed, but a very purely practical basis. In either case the ques great deal of time, enthusiasm and resources posed in the earlier field trials should aim have been expended fruitlessly in African terri- to locate the threshold of response to a treat stories because such conditions have been government, the range of dressings, dosages, or con looked or ignoredItem Practical Aspects of Field Experimentation in Africa(1960) Pereira, H.C.; Vernon, A.J.; East African Agriculture and Forestry Research Organization, Muguga, Kenya and Rothamsted Experimental Station, Harpenden, Herts.This is a brief survey of some of the points which most need attention in field experimental work under African conditions, where many experiments are carried out by isolated officers who have little chance of discussion with technical colleagues. Many of the points appear quite obvious when listed, but a very great deal of time, enthusiasm and resources have been expended fruitlessly in African territories because such conditions have been overlooked or ignored.Item The Seasonal Assessment of Water Needs In The Irrigation of Coffee(1956/1957) Pereira, H.C.In the areas of unshaded Kenya coffee east of the Rift, planters realize very keenly how dependent are their crop yields upon the vagaries of rainfall. Every coffee planter can do a certain amount to help himself out of these difficulties. The Coffee Research Station at Ruiru, Kenya, has shown what substantial increases in yield can be obtained by securing full penetration of rainfall and its subsequent protection by the use of grass mulches, and this practice is being widely followed. Improved weeding efficiency with implements specially devised to leave a rough cloddy surface which can effectively absorb rainfall, has been shown at the Coffee Research Station to be another profitable way of securing a better share of the rainfall for the coffee (Pereira and Jones, 1954); the encouraging results reported by Robinson (1956) suggest that the supplementing of cultivation by weed killing sprays may soon become routine practice. The third method of assistance to the coffee is the most direct but the most expensive, that of supplementary irrigation. This has been pioneered by enterprising planters, encouraged by the high coffee prices of recent years, and striking responses have been obtained from water applications.Item The seasonal assessment of water needs in the irrigation of Coffee(1957) Pereira, H.C.; East African Agriculture and Forestry Research OrganizationIn the areas of unshaded Kenya coffee east of the Rift, planters realize very keenly how dependent are their crop yields upon the vagaries of rainfall. Every coffee planter can do a certain amount to help himself out of these difficulties. The Coffee Research Station at Ruiru, Kenya, has shown what substantial increases in yield can be obtained by securing full penetration of rainfall and its subsequent protection by the use of grass mulches, and this practice is being widely followed. Improved weeding efficiency with implements specially devised to leave a rough cloddy surface which can effectively absorb rainfall, has been shown at the Coffee Research Station to be another profitable way of securing a better share of the rainfall for the coffee (Pereira and Jones, 1954); the encouraging results reported by Robinson (1956) suggest that the supplementing of cultivation by weedkilling sprays may soon become routine practice. The third method of assistance to the coffee is the most direct but the most expensive, that of supplementary irrigation. This has been pioneered by enterprising planters,encouraged by the high coffee prices of recent years, and striking responses have been obtained from water applications.Item Tea Gardens or Tall Forests?(1959) Pereira, H.C.; East African Agriculture and Forestry Research Organization, Kikuya Kenya. Tea Research Institute of East Africa, Kericho KenyaItem A Tillage Study in Kenya Coffee(1954) Pereira, H.C.; Jones, P.A.; East African Agriculture and Forestry Research Organization and Coffee Research Station, Ruiru.The results are presented for the first 5 years of a tillage experiment on arabica coffee involving 3 types of implement (forked hand hoe, tractor-mounted disc harrows and tractor-mounted 3-furrow plough), 3 depths of cultivation down to 6 inches, 3 sub-soiling treatments and 3 weed control policies, namely, (a) clean cultivation, (b) weeds slashed during the two rainy seasons each year and cultivated at the onset of dry weather, and (c) unrestricted weed growth during the rains killed by cultivation only at the onset of dry weather. Weed growth seriously reduced coffee yields in each year, the reductions for 5 years being 39 % for unrestricted weed growth and 27% when weeds were slashed. The highest yields were produced consistently by clean weeding with the forked hoe. Averaged over all weed conditions, disc harrowing gave yields significantly lower than either hoeing or ploughing. Neither depths of tillage nor sub-soiling produced significant yield differences. Cattle manure applied to sub-plots to encourage different levels of weed growth did not increase coffee yields. Tillage treatments had no significant effects on the quality of the crop.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.
