Phosphorous: a prerequisite for increased productivity of forage and browse/tree legumes in the Ethiopan highlands
1996
Lupwayi, A.Z. | Haque,I. (ILCA, Addis Abeba (Ethiopia))
Phosphorus is probably the most limiting nutrient for production of legumes in tropical regions. It is particularly deficient in the soils of the Ethiopian highlands, where 82 percent of the soils are P deficient and concentration of Bray-II extractable P as low as, or lower than 1ppm are not uncommon. Thus, in some vertisols, forage and browse/tree legumes completely fail to nodulate when P fertilizer is not applied. When P is applied, dry matter (DM) and 1178% in Ultisols. Phosphorus fertilizers are expensive because they are imported. Identification of legume genotypes tolerant to low levels of soil P is one approach to alleviate this problem. Inoculation of plants with mycorrhizae can increase their uptake of P, but the inoculum is difficult to produce and introduce to the soil. Another way is to use rock phosphates, which are a much cheaper source of P. Agronomic trials show promising results with Trifolium spp. on Vertisols. Therefore, further research or other legumes in different soil types in recommended. In any case, a P fertilizer manufacturing, mixing or trading body is required in Ethiopia to reduce the price of the currently imported fertilizer.
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