Residual Effect of the Chemical and Organic Fertilization on the Initial Growth of Cotton Plant Irrigated with Freshwater and Domestic Effluent

Abstract

In the last few decades, the environmental preservation has become factor of great social and economic importance. Continuous efforts have been carried through in order to develop alternatives of residues recycling to make possible the prevention and control of the pollution. Amongst the measures most promising can be detached the organic fertilization and wastewater reuse, that allow the soil fertilization by means of the application of residues characterized by the high organic content. However, more detailed studies in this direction should be done to minimize the possible sanitary risks of these practical. Therefore, the objective of this work was to evaluate the residual effect of chemical and organic fertilizers applied in sesame (Sesamum indicum L.) on initial growth of cotton (Gossypium hirsutum L.) cultivated in succession crop, when irrigated with treated domestic effluent and freshwater. For this, cotton plants was cultivated in 20 L pots previously cultivated with sesame plants, which was submitted to the treatments that resulted of factorial combination of five levels of castor meal (0, 2, 3, 4 and 5 ton ha-1), two qualities of irrigation water (freshwater and domestic wastewater), and two additional treatments with chemical fertilization (NPK + freshwater and NPK + wastewater). The wastewater was treated in an anaerobic reactor and the irrigation was carried through daily in accordance with the water cotton demand. Plants height, leaf area and mean leaf number/plant were evaluated at thirtieth and fiftieth days after emergency. Results showed that the residual effect of organic fertilization with castor meal provided to greater initial growth of cotton plant. The irrigation with domestic wastewater propitiated greater initial growth of cotton plants in relation to freshwater irrigation.