Crushed cotton gin compost on soil biological properties and rice yield

Abstract

This study presents an account of soil quality parameters and rice ( Oriza sativa cv. Puntal) yields as influenced by applying an organic waste (crushed cotton gin compost, CC). Such information is desirable for determining the suitability of renewable energy resources such as organic wastes as replacements for synthetic fertilizers. However, CC has low N levels. For this reason, some authors suggest co-applying mineral fertilizers to provide the nutrients plant requires in the early stages of development. The main objective of this work was to study the effect of incorporating CC at rates of 10, 15 and 20 t ha −1 with and without inorganic fertilizers on soil biological properties (soil microbial biomass, soil respiration and soil enzymatic activities), nutrition (pigments and leaf soluble carbohydrate concentrations) and yield parameters of rice ( O. sativa cv. Puntal) crop for three years on an Aquic Xerofluvent located near Sevilla (Spain). Soil biological properties increased when CC was applied with inorganic fertilizers. Since soil enzymatic activities measured are responsible for important cycles such as C, N, P and S, an increase of leaf soluble carbohydrate contents and pigments were observed, and better rice yield parameters were obtained for soils treated with CC + inorganic fertilizers. Yield parameters of the third experimental season were better than those of the second and first experimental season, due to the residual effect of the organic matter after their application in the first season. The application of CC + inorganic fertilizers in soils increased the grain protein concentration (18%), the grain starch concentration (7%), the percentage of full grains (3%) and the rice yield (5%) with respect to the application of CC without inorganic fertilizers in soils.