Fertilizer Experiments on Grassland in the Kenya Highlands

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Dougall, H.W
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In 1926 attention was directed by the Committee of Civil Research [1] to the grasslands of Kenya, when this Colony was selected by it as the most suitable for pursuing an inquiry into the mineral content of natural pastures. Boyd-Orr, who directed this investigation, selected four districts (Naivasha, Athi Plains, Nakuru, Molo), in which he studied the chemical composition of natural herbage as affected by soil and climate. Results of preliminary work indicated clearly that, in three of the four districts, pastures were deficient in all mineral nutrients and also in protein. Phosphorus was the element most deficient, and he considered it to be the factor limiting the assimilation of other minerals by the plant. Boyd-Orr inclined to the view that if phosphorus were supplied by fertilizers, the amount not only of phosphorus but also of calcium would be increased in the pastures. However, when the most deficient area was treated with fertilizers, * the first direct effect to be measured was productivity and yields of herbage were increased from 25 per cent, when common saIt was used, to well over 300 percent where nitrogen and phosphate were used together. It is unfortunate that the composition Of the herbage harvested was not reported, but we may infer that its mineral status was enhanced, for it is recorded that when stock were allowed access to the plots at the end of the test, they "showed a marked preference for those which had been fertilized, while con (rols were left practically untouched". It was observed that where phosphates had been Applied the herbage maintained its green appearance for a longer period during subsequent dry weather
East African Agricultural And Forestry Journal, XIX (No 3), p. 171-178