Soil properties, growth and yield of cocoa (Theobroma cacao L.) trees from moribund field as affected by pruning and fertilizer application

Abstract

An experiment was conducted to investigate the effects of fertilizer application and pruning on soil properties and performance of cocoa trees from a moribund field. The fertilizers (NPK compound inorganic fertilizer and poultry manure) and pruning intensities (none, moderate and heavy branch removal) had significant effects on soil properties and flower production, pod and bean yields of cocoa trees. The fertilizers enhanced soil fertility (increased soil pH, organic carbon, N, P, K, Ca and CEC). Heavy pruned cocoa trees produced significantly higher number of pods per tree (49.7) compared with moderate pruning (42.4) and unpruned (45.3). Cocoa pods were heavier for heavy pruned trees (1.4) compared with the unpruned (1.2) and moderate (1.01) pruning intensities. Total bean weight was high for heavy pruning (0.34 kg) followed by the unpruned trees (0.32 kg) and lowest for moderate (0.28 kg) pruning treatment.  Pod weights were 2.83 and 2.74 kg for trees treated with poultry manure and NPK amended soils compared with unamended (2.38 kg). The number of beans per pod was respectively, 226.4, 211.7 and 206.4 while weight of beans per tree was 0.76, 0.70 and 0.64 kg for poultry manure, NPK and no amendment. Poultry manure treatment of heavy pruned cocoa enhanced weights of pods and beans compared with NPK while lowest values were recorded for unamended trees. Pruning enhanced cocoa tree vigour by reducing shade density and competition for assimilate from organs (root, branches, leaves) and promote light regime and health of trees. The fertilizers improved soil physical, chemical and biological properties for cocoa tree productivity. There were positive and significant impacts of rehabilitation practice involving pruning and fertilizer amendment for rejuvenation and enhanced performance (flowering, pod and bean production) of old, moribund cocoa trees.