Macronutrients in Soil and Lettuce After the Irrigation with Effluents of Stabilization Pond

摘要

The disposition of sewers into the soil is an old practice, dating since the centuries XVI and XVII in Germany and in England. The treated wastewater has been used in the irrigation not only for providing a continuous supplying of water, but also dueto its high nutritional power, which reduces or even eliminates the need of chemical manuring. The present work tells an experience of direct reuse of sewer treated at a pond of stabilization in the cultivation of the lettuce (Lactuca sativa, L), evaluating the chemical modifications that happen in the soil and in the vegetable with the application of wastewater and of the addition of the organic manuring. The experiment was conducted in the Campina Grande Sewage Treatment Plant, Paraiba state, Brazil,in a randomized experiment with four replications, being the factors two types of irrigation water (provision water and wastewater treated by stabilization ponds) and the presence or absence of bovine manure. Two cycles of lettuce cultivation were carried out and statistically analyzed: the first one from July to August of 2003 and the second from October to November of 2003. Macronutrients analyses were accomplished in soil and lettuce root. The addition of the organic matter through bovine fertilizerpromoted larger alterations in the chemical characteristics of the soil and of the lettuce.