Biochar-Compost From Cashew Apple Residue as a Soil Amendment for Cashew Cultivation in Ghana

The study investigated the effect of different compost types on the growth performance of cashew (Anacardium occidentale L.) varieties cultivated in a Lixisol from Northern Ghana. Six compost formulations were prepared using various combinations of poultry manure, cow dung, biochar, and cashew apple residue at different mixing ratios. The experimental design was a completely randomized block design arranged in a 2 × 6 factorial structure with three replicates. Three cashew varieties were planted at a spacing of 10 m × 10 m and amended with compost types at a rate of 50 kg ha^-1. Growth parameters were recorded over two seasons, while nut yield was recorded in year 2. Results showed that cashew apple residue combined with biochar and poultry manure produced composts with higher organic carbon (OC) and total nitrogen (N) than the controls. In the first year, variety B3T101 treated with either cow dung or a mixture of poultry manure, biochar, and cashew apple residue in a 2:1:1 ratio recorded significantly (p < 0.05) higher heights (205.70 and 193.00 cm, respectively). However, in year 2, all compost types had statistically similar effects on plant height (p < 0.05). Variety B3T57 treated with poultry manure alone and biochar-poultry manure-cashew apple residue had statistically similar (p < 0.05) nut yield of 803.70 and 872.30 g, respectively. The findings demonstrate that cashew apple residue is as valuable as the traditional decomposed cow dung and poultry manure used in cashew farming for use as an organic fertilizer in cashew farming.