EFFECT OF FARMYARD MANURE, STARTER NITROGEN AND PHOSPHORUS ON SELECTED SOIL PROPERTIES, GROWTH AND YIELD OF GREEN GRAMS IN TITANIUM MINED SOILS

Abstract

Globally, mining is an important fiscal activity that promotes income generation, job creation, and industrialization. However, mining is classified as a major form of land degradation that leads to disruption of natural ecosystem balance leading to loss of flora, above ground biota as well as soil Health. Completion of mining process calls for reclamation of the degraded land to productive use through establishment of grass, trees or crops. Choice of reclamation method is however depended on mining method. A field study was conducted at Base titanium limited-Kwale County, to investigate the potential of titanium mined soils to support growth and yield of green grams through farmyard manure, starter N and P application. Treatments were laid down in randomized complete block design (RCBD) with split plot arrangement with three replications. The treatments included: manure (M), starter nitrogen and phosphorus (F), manure plus starter nitrogen and phosphorus (M+F) and control (C). Data collected included initial and final soil physio-chemical properties, plant height, number of leaves, root depth, number of pods per plant, number of grains per pod, root nodulation, plant biomass, and yield. Obtained data was subjected to Analysis of Variance (ANOVA) usingthe Genstat statistical package and means ranked using Fisher's protected least significant difference. The results showed that the soils at the study site was slightly acidic (pH 5.8-6.4) with a sandy loam texture and low levels of TN, exchangeable P, K, S, Bo and Cu. A significant increase in nitrogen, phosphorus and potassium levels were observed in manure plus starter NP treated soils. Manure application significantly increased plant height by 30% and 50% and grain yield by 45% in KS20 and N26 varieties respectively. Sole starter NP application was observed to increase plant height, leaf development, nodulation rate and yield compared to control although, the effect was not significant. Manure plus starter NP significantly increased green grams height by 56%, leaf number by 80% and grain yields by 50% compared to control. In addition manure plus starter NP increased grain yields in N26 variety by 40% compared to KS20 variety during cropping season two. Although , grains yield from both varieties were lower than the national average yield (1.5tons/ha), they had adequate level of P, Fe, Zn, Mg and K. Combination of manure and inorganic fertilizer was found to be most effective in enhancing green grams growth and yield. It can, therefore, be concluded that synergistic effect of manure and starter NP can support optimal green grams production in these soils. Further research is, however, advocated to ascertain approaches that can ensure long term soil profile development while ensuring sustainable crop production in titanium mined soils.