Modificações no ambiente edáfico, na água e na mamoneira submetidos ao uso de biossólido e água residuária.

Abstract

Wastewater as well as sewage sludges have high contents of organic material and minerals, especially nitrogen and phosphorus as well as micronutrients. The use of these materials in agriculture decreases and in some cases eliminates the need for the use of chemical fertilizers In this thesis an experimental investigation is described into the effect of irrigation with wastewater and the application of biosolids on the culture of castor bean The work was carried out in the context of the Program for Basic Sanitation Research (PROSAB), Campina Grande, PB. The experiment was entirely randomized, with 7 treatments and 3 repetitions in a factorial scheme (2x3+1) represented by two types of water (public supply and treated wastewater) and three doses of biosolids (0, 75 and 150 kg N ha"1) and a witnesses where chemical fertilizer was applied. The water as characterized by determining the concentrations of organic material (COD) and nutrients (ammonium nitrogen and total and soluble phosphate). As for the culture the following variables were analyzed: plant height, stem diameter, leave area, number of leaves, size and number of spike, number of per spike, weight of 100 seeds and seed production per plant. In order to accompany the impact on the soil, the physical characteristics as well as fertility, salinity and micronutrients concentrations were determined at the beginning and at the end of the experiment. The waters used for irrigation presented calcium, magnesium, bicarbonate and conductivity contents inside the recommended standards. The drainage liquid presented an elevation in the electric conductivity, increasing the risks of soil salinization and deterioration of underground waters. The treated wastewater presented, nitrogen and phosphate above adequate values. The results showed that all va riables of growth and productivity of the castor bean plants irrigated with treated wastewater were superior to those irrigated with water, especially regarding the production per plant which was 1932%. The soils of the treatments with wastewater showed increase of the organic material and nitrogen and phosphorus, which are essential nutrients for the developments of the plants. The biosolids presented significant effect, for the variables: plant height, stem diameter, leave area, number of leaves.