Sorghum Growth and Yield as Influenced by Farmyard Manure and Inorganic Fertilizer in Post Mined Soils

Abstract

Mining plays an important role in Kenyan Economic development through provision of employment, raw materials 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 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 Kwale Company. The experiments were laid down in Randomized Complete Block Design (RCBD) with split plot arrangement and replicated thrice. Fertilizer, Manure, Manure + Fertilizer, Control (unfertilized) and Gadam and Silla sorghum varieties were tested. Data collected included: Initial soil properties, plant height, number of leaves, leaf length, leaf width, stem circumference, panicle length, panicle circumference and grain yield per hectare. Data collected was subjected to analysis of variance using Genstat software and means separated using the Fisher’s protected least significant difference at (P≤0.05). The soils were slightly acidic with low levels of exchangeable P, K, S, Cu and Bn. Manure + fertilizer significantly (P≤0.05) increased plant height by 14% (gadam), and 28% (silla), number of leaves per plant by 28% (gadam) and 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. Where gadam produced slightly high grain yield than silla variety by 7%. Combined application of farmyard manure and inorganic fertilizer were most effective in enhancing sorghum growth, dry matter and yield. Growth and yield data collected showed that combined farmyard manure + fertilizer can support optimal sorghum production in the post mined soils. Owing to the fact that the soils have compromised profile, soil structure and fertility, long term trials and simulation models are required to ascertain optimal sorghum production while ensuring sustainable soil health in such soils.