Impact of agroforestry parkland system on maize productivity by smallholder farmers in Eastern highlands of Kenya

Abstract

A field experiment was carried on farms at Kyeni South in Eastern highlands of Kenya. The purpose of this study was to investigate on the effects of identified common tree species on growth and yield of maize on farms. The selected tree species found to be prevalently growing on farms were Croton macrostachyus Hochst. Ex Delile, Cordia africana Lam. and Grevillea robusta A. Cunn. Growth in basal diameter, height, leaf chlorophyll content and final grain yield was assessed on maize plants selected from the plots under the trees and control plots (away from trees). The maize plants in G. robusta plots had significantly lower mean basal diameter of 1.67 cm at 6 weeks after crop emergence (WACE) and 1.96 cm at 9 WACE. No significant differences were observed in plant height in plots under different tree species. Significant suppression of chlorophyll development in maize (indicated by SPAD readings) was observed in all the plots under the identified tree species at 6 WACE (P < 0.01). G. robusta plots had significantly lower grain yield of 1.57 t ha-1 compared to the control plots that had the highest mean yield of 2.21 t ha-1. Proper crown management is necessary in agroforestry systems.