Ten cattle and goat manure-based phospho-composts, CD and GM, respectively, were evaluated along with single-superphosphate (SSP – 10.5% P) and unfertilized treatments under field conditions using maize as test crop. The phospho-composts were produced through thermophilic co-composting of various mixed ratios (9:1, 8:2, 7:3, 5:5, 10:0) of the manures and non-reactive ground phosphate rock (36.5% P2
); and applied at a rate of 60 kg P ha-1
. Treatments were laid out as a randomized complete block design with four replications. Maize growth, yield and grain quality parameters as well as agronomic phosphorus (P) -use efficiency (PUEA
) were obtained and subjected to analysis of variance. Results revealed that the GM-based phospho-compost mix ratio of 8:2 gave the highest grain yield of 6987 kg ha-1
, which was marginally higher than the grain yield obtained from SSP fertilized plots. Similarly, CD-based phospho-composts mix ratio of 8:2 gave the highest starch content of 72.0% as well as PUEA
of 86.5%. Co-composting of ground phosphate rock with manures resulted in increase of P availability from the ground non-reactive phosphate rock to plants. Phospho-compost application resulted in increased grain yield and grain quality while the agronomic P-use efficiency of the phospho-composts produced were generally comparable to that of inorganic P fertilizer.
Keywords: Phosphorus, agronomic P-use efficiency, phospho-compost fertilizer, grain yield, grain quality, ground phosphate rock