Onion (Allium cepa L.) Performance as Influenced by Manure and Fertilizer in Titanium Mined Soils

Mining is an important economic activity that promotes income generation, job creation, and industrialization globally. In spite its economic importance, it is classified as land degradation form that disrupts natural ecosystem through loss of biota and soil health. Paucity of information regarding the performance of reclaimed mined soils in supporting crop production abound in Kenya. To contribute to this knowledge gap, a study was conducted at Base titanium limited -Kwale to investigate the response of performance of bulb onions (red creole onion variety) to farmyard manure and inorganic fertilizer application on post mined soils. The experiment was laid out in a Randomized Complete Block Design (RCBD) with three replicates Treatments included- inorganic fertilizer, farmyard manure, inorganic fertilizer +farmyard manure and control. Obtained data that included- soil characterization, onion growth and yield parameters was subjected to analysis of variance (ANOVA) using R packages and means separated using the Fisher's protected least significant difference (LSD) at (P≤0.05). Results showed that the soils had low TN, exchangeable P, K, S, Bo and Cu levels. Manure+ fertilizer significantly (P≤0.05) increased plant height by 38%, bulb diameter by 44%, neck thickness by 19.5% total bulb yield by 89% and marketable yield by 88% compared to control. A significant positive relationship between manure, fertilizer, fertilizer+ manure with plant height, number of leaves, bulb diameter, neck thickness and total yield was observed indicating that manure + fertilizer can support optimal onion production in these post mined soils. Further research is however, required to ascertain production approaches that promote sustainable soil development and onion yield.