G. Soropa, G. A. Mavima, S. Musiyandaka, T. P. Tauro and F. Rusere
A study was conducted to determine phosphorus (P) mineralisation and agronomic potential of pelletized phosphate blends (PPB) enhanced cattle manure using incubation and green house experiments for two soils in Zimbabwe. Under incubation, the rate of P mineralization for untreated and PPB treated manures was determined using the Bray 1 method on destructive samples (2 g sub-sample) of the soils collected 3, 7, 14, 28 and 42 days after incubation had commenced. A green house experiment was established to test for direct and residual effect of 10 and 20 t ha-1 of untreated and PPB enhanced cattle manure on P uptake and crop growth using maize as a test crop for 5 weeks after crop emergence (WACE). The pots were arranged in a randomized complete block design with each treatment replicated three times. The results of the incubation study showed a significant decrease in the amount of P release into solution for the two soils. The greenhouse results showed no significant (p < 0.05) difference in the maize biomass yield at 5 WACE between the untreated and PPB enhanced manures from both soils. However, the maize P uptake differs with soils across all the treatments. There was no significant (p < 0.05) difference in the available P in the biomass harvested among all the treatments regardless of soil type used. The study confirmed that if rock phosphate is mixed with cattle manure without composting, there is no improvement in P availability and uptake by maize.
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