Capacidade de armazenamento e controle da erosão e do escoamento superficial de terraços em nível em sistema de plantio direto.

Abstract

Water erosion is the main source of soil degradation, being caused by the impact of the raindrop as well as runoff, as both have the capacity to disaggregate and transport soil, in addition to reducing the productive capacity of the land. The research aimed to evaluate soil losses and runoff in no-tillage in the presence and absence of agricultural terraces, in addition to evaluating the temporal effect of terraces on their capacity to store water and retain sediments in mediumtextured soil in the region of Campos Gerais, Paraná. The treatments consisted of two plots, with an average area of 1.54 ha, the first one adopting no-tillage without terracing, and the second using the same management, but associated with level terraces to control runoff. The plot with terraces reduced, on average, the total runoff by 49.6%, the peak flow by 72.1% and the suspended sediment concentration by 70.8%, compared to no-tillage without terraces. The terraces had a reduction in their base, height and section dimensions by an average of 15%, 35% and 46% after 571 days of evaluations, demonstrating a marked reduction in the damming capacity of surface runoff. The deposition of sediments in the terrace channels was correlated with precipitation and rainfall erosivity, increasing by 1.66 times when the precipitation doubled and by 1.53 times when the erosivity was doubled.