GROWTH AND YIELD POTENTIAL OF SORGHUM AS INFLUENCED BY MANURE AND INORGANIC FERTILIZER IN POST MINED SOILS

Abstract

Mining plays an important role in Kenyan economy through provision of employment opportunities, raw materials for industries as well as foreign income. Despite the important role played by this sector, it is associated with land degradation, impacting food security. Closure of mines calls for rehabilitation process that can be done through establishment of native trees, grass or crops. In order to promote crop production as a reclamation measure, performance of sorghum in post mined soils was evaluated in the south dune site of base titanium limited Company, Kwale County. The experiment was laid down in Randomized Complete Block Design (RCBD) with split plot arrangement and replicated thrice. fertilizer, manure, fertilizer +manure, control (unfertilized) and Gadam and Silla sorghum varieties were evaluated. Data collected included: Initial and final soil chemical characteristics, plant height, number of leaves, leaf length, leaf width, stem circumference, root depth, root width, panicle height, panicle circumference and grain yield per hectare. Data collected was subjected to analysis of variance (ANOVA) Genstat packages and means separated using the Fisher’s protected least significant difference (LSD) at (P ≤ 0.05). Obtained results revealed that the soils were slightly acidic with low levels of exchangeable P, K, S, Cu, CEC, TN and Bo and, ideal levels of Ca, Na, Mg, Fe, Mn, and Zn. Manure + fertilizer significantly (P ≤ 0.05) increased plant height by 14% (Gadam), 28% (Silla), number of leaves per plant by 28% (Gadam) 29% (Silla), panicle length by 18% (Gadam), 8% (Silla), dry matter by 30% (Gadam) 40% (Silla) and grain yield by 50% for both Gadam and Silla varieties compared to control plots in both varieties. Average yields in both seasons for manure + fertilizer treated plants were significantly high (5.3 tones/ha) for Silla variety and (5.7 tones/ha) for Gadam variety. Average Gadam yield was 7% higher than Silla. It can, therefore, be concluded that manure and inorganic fertilizer can support optimal sorghum production in these soils. Owing to the fact that this post mined soils have compromised profile, soil structure and fertility, further research is advocated to investigate sustainable approaches that can ensure optimal tillering ability while promoting soil profile development and health.