Effects of Cowpea Residues, Chicken Manure and Partially Acidulated Phosphate Rock on the Fertility of Two Acid Soils for Maize Production in Lusaka- Zambia

Aim: To assess the use of chicken manure pellets, partially acidulated phosphate rock (PAPR) and cowpea residues to enhance the fertility and productivity of two Kandiustalfs in Zambia.

Methodology: Six treatments; chicken manure, PAPR, cowpea residues, chicken manure with PAPR, cowpea residues with PAPR and no amendment (control) were assigned to 4 m x 4 m plots on each soil. The PAPR was applied at a rate of 40 kg P2O5/ha, chicken manure at 20 kg N/ha and cowpea was planted in rows 45 cm apart. Cowpeas or weeds were allowed to grow on each plot for four months when cowpea pods matured. Plants were cut, incorporated into the soil and left to decompose for six weeks. Soil samples were then collected for analysis of organic matter, N, P, K and greenhouse maize trials.

Results: Cowpea residues, chicken manure and chicken manure with PAPR significantly increased levels of organic matter. Cowpea residues and cowpea residues with PAPR significantly increased levels of available N than the control. Available P levels significantly increased with application of cowpea residues and chicken manure with PAPR. Application of cowpea residues, cowpea residues with PAPR and chicken manure significantly increased levels of K than the control. Cowpea residues and cowpea residues with PAPR significantly increased maize dry matter yields than the control. The relative agronomic effectiveness (RAE) of cowpea residues was 66% on Chakunkula soil and 37% on Choma soil respectively.

Conclusion: Cowpea residues are potential means of improving the fertility and productivity of acidic Alfisols especially for resource poor farmers with limited access to chemical fertilizers.