EFFECT OF AMMONIUM SULPHATE FERTILIZATION ON SOIL CHEMICAL COMPOSITION, FRUIT YIELD AND NUTRIENT CONTENT OF OKRA
Keywords:Soil chemical composition, nitrogen fertilization, N fertilizer, continuous cropping
The effects of continuous nitrogen fertilization (NH4)2SO4 on changes in soil chemical composition and on the yield and nutrient content of Okra (Hibiscus esculentus L.) leaves were studied in the field. Ammonium sulphate when applied as N fertilizer source, drastically decreased soil PH and yield. Soil OM (organic matter), K and Ca decreased, NO3 N and P increased with continuous cropping as compared to soil values prior to cultivation. Leaf nutrient concentration at various stages of the plant growth was affected by nitrogen fertilization. Soil organic matter was positively correlated with leaf K. Ca and Mg (r = 0.72**, 0.67** 0.72** respectively), whereas soil pH correlated positively with leaf NO3 N and P (r = 0.67**, 0.91*** respectively). A positively significant correlation was established between okra yield and leaf Mg when sampled at the vegetative (r = 0.59*) and at the flowering (r = 0.72**) stages of growth, and with leaf P (r = 0.92**) at the fruiting stage of growth. It is suggested that (NH4) 2SO4 fertilizer if applied to an acid soil, should be combined with a liming material to increase soil pH so as to obtain a more favourable growth and yield of the okra plant.