Sustaining Soil Organic Matter for Okra Production in a Forest Ecology of Nigeria

Abstract

Okra production in Nigeria is particularly under smallholder and resource-poor farmers. This study therefore investigated the influence of aerobically composted cowdung (CWD), singly and in combination with Ogun rock phosphate (ORP) applications on the yield of okra and soil organic matter maintenance in typical forest ecology of Nigeria. The study was conducted during two different okra cropping seasons. The experiment was in a randomised complete block design of four, 27.0 m x 4.0 m blocks; each was divided into seven plots of 4.0 m x 3.0 m with an alley of 1.0 m between blocks and 1.0 m within plots. The treatment plots were made up of crop with: 100% CWD, 100% ORP, 20% CWD + 80% ORP, 40% CWD + 60% ORP, 60% CWD + 40% ORP, 80% CWD + 20% ORP and zero percent application served as control. The seven organic fertilizer treatments were applied at planting, and at the rates of 6.0 and 0.3 t ha-1 for 100% CWD and 100% ORP respectively. Each of the treatments was replicated four times to give a total of 28 plots. Highest fresh okra mean yield of 22.9 ± 1.3 t ha-1 obtained with 60% CWD + 40% ORP was only significantly (p = 0.05) different from 14.2 ± 1.2 t ha-1 obtained with zero treatment application. This experiment was repeated two more times, but without treatment applications. About 5% reduction and over 100% increase in soil organic carbon and available P respectively were achieved after third consecutive okra cultivation. We therefore concluded that aerobically composted cowdung when complemented with Ogun rock phosphate enhanced the quantity of okra and soil organic matter of the study area.