Reuso de sedimentos de reservatórios e seus impactos nos parâmetros fisico-hidricos em substrato agrícola

Abstract

The accumulation of sediments in the bed of weirs is a process resulting from the erosion occurrence. Soil and organic matter from higher points are carried by the streaming water to the lower points of a watershed. This displacement of material implies two problems: a diminished water storage capacity and the accumulation of nutrients with the probable occurrence of eutrophication. A common practice in the maintenance of reservoirs and dams is to remove this material, seeking to avoid problems such as eutrophication and recover the original capacity of the reservoir. However, there are other purposes for this sediment that can positively impact agricultural activities and consequently the environment. The reuse of this sediment as a tool for maintaining soil fertility, both in terms of chemistry and soil physics, has proven to be a promising soil management alternative. Therefore, this work aims to evaluate the performance of the addition of sediment to modify the physical-hydric properties of the soil in vases with maize croping. Five treatments were used, with different levels of sediment in t.ha-1 from the São Nicolau reservoir in the city of Madalena – CE: 0 t.ha-1 (witness), 25 t.ha-1, 50 t.ha-1, 75 t.ha-1 e 100 t.ha-1. The parameters measured in the laboratory were soil-substrate density (Ds); particle density (Dp); porosity (P); and saturated hydraulic conductivity (Ks). The water retention capacity was also measured in the green house by automatic humidity sensors connected to a datalogger and the water consumption (water demand) through the collected drained volume from each irrigation. A significant difference (α = 0.05) in ANOVA test was observed for the results of water demand and Ks, and through linear regression was constructed a trend line with a defined confidence interval for the variation of Ks values. A decrease in Ks was observed as a function of increasing sediment doses probably due to the greater accumulation of fine particles in the substrate.