Fortification of compost with Phospate rock (A field experiment)

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Daka, Lovemore
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Zambia is well vested with many natural resources that have not been expected. One of such resource is the Chilembwe phosphate rock (PR) found in eastern province. The particular rock is of ingenious origin, hence having a very low solubility rate. Direct application of phosphate rock on fields of annual crops has been attempted but yields have not improved significantly. Therefore, only perennial crops can benefit from this material over a long period of time. Nevertheless, the production of chemical fertilizers such as Triple Super Phosphate involves the reaction of phosphate rock with orthophosphoric acid. This particular acid is very expensive, thus increasing the costs of fertilizers. The low soil fertility coupled with high costs of fertilizers has resulted into low crop yields in most developing countries. For this reason, poverty levels have exacerbated such that attaining the millennium development goals by the year 2015 is a mare phallus. Cheaper methods of solubilizing this valuable material need to be invented. The fortification of compost with phosphate rock is one of the promising ways of making phosphorus available for plant uptake. The process relies on the presence of organic acids that are secreted microorganisms during decomposition of organic matter. The research on fortification of compost with phosphate rock was carried out at the University of Zambia, 'field station' from 01-08-05 to 23-12-05. Five compost heaps were made. The rates of phosphate rock added to each compost heap were 0.00kg, 2.41kg, 4.82kg, 9.61kg and 14.47kg that corresponded to 0, 20, 40, 80 and 120kg P2Os per hectare respectively. Incubation of composts lasted for two months, followed by application and planting of green beans. Phospho-Compost and soil samples were tested for available phosphorus in the laboratory. Also plant tissue analysis for phosphorus was done. The biomass and weight of pods per plant were measured on dry basis. It was discovered that the 40kg/ha level of phosphate rock produced the highest crop yield as compared to other levels.
Phosphate rock , Compost