Green Grams (Vigna radiata L.) Performance in Post Mined Soils When Subjected to Organic and Inorganic Fertilizers

Abstract

Though mining promotes global industrialization and economy, it disrupts natural ecosystem that calls for sustainable reclamation. A field study was conducted at Base titanium limited - Kwale County to investigate the potential of mined soils to support growth and yield of green grams when subjected to organic and inorganic fertilizers. A two factor experiment was laid down in RCBD with split plot arrangement and three replications. Green gram varieties (KS20 and N26) and amendments (organic and inorganic fertilizers) were tested. Obtained data that included: soil properties, plant height, leaf development, pods and grains per plant, root nodules, biomass, and grain yield was subjected to ANOVA using the Genstat statistical package and means ranked using Fisher's protected least significant difference at (P≤0.05). Results showed that combined manure and fertilizer significantly improved plant plant height by 36% and 36.4% for KS20 and N26 varieties respectively in season one and, 23% and 23% for KS20 and N26 varieties respectively in season two compared to unfertilized soils. Similarly, leaf development was increased by 54.9% and 52.2% for KS20 and N26 varieties respectively in season one and, 46.1% and 37% for KS20 and N26 varieties respectively in season two compared to unfertilized soils. Sole manure and sole fertilizer did not have significant effect on plant height and leaf development. Combined application of manure and fertilizer did not have significant influence on green gram nodulation, shoot and root dry matter accumulation, number of seeds per pod and pods per plant. It however increased N26 variety grain yield in the second season alone. Additionally, grains harvested from the post mined soils had adequate levels of phosphorus, Iron, Zinc, magnesium, potassium, and low levels of calcium and copper. Although the findings show that this post mined soils have the capacity to support green gram growth, further research to ascertain long term effects of green gram establishment on profile development, biological nitrogen fixation, enterprise return to capital and crops response after application of all limiting nutrients is recommended.