Perdas de solo por erosão hídrica em lavouras anuais por meio demModelos hidrológicos distribuíos

Abstract

Erosive processes caused by intensive soil use and inadequate agricultural practices in the State of Paraná resulted in major losses from the 1970s onwards. Since then, agricultural practices such as the Direct Planting System and the implementation of terraces have been important measures in controlling soil erosion. erosion in the state. However, from the 2000s onwards, erosion processes intensified again with the removal of terraces by many producers, mainly in the southwest region of Paraná, where the predominance of undulating relief and the strong erosive potential of rains, rekindled the warning regarding the increased soil losses. In this sense, it is important to quantify, estimate and simulate erosion processes in these environments, to manage them appropriately and guarantee sustainable agricultural production. Therefore, this work aimed to evaluate soil losses due to water erosion using Drone, GRASS GIS and portable collectors installed in the soil. Soil losses under natural conditions were evaluated in two annual crops separately, beans and white oats, cultivated successively. The design used was completely randomized with four treatments in the bean crop and five treatments in the white oat crop, both with three replications. The bean crop treatments were composed of T1 = bare soil, T2 = low soil coverage, T3 = intermediate soil coverage and T4 = maximum soil coverage, and the white oat treatments were composed of T1 = bare soil, T2 = low soil coverage, T3 = intermediate soil coverage, T4 = high soil coverage and T5 = maximum soil coverage. Soil losses due to water erosion were collected from 02/27/2023 to 08/10/2023 after each rainy event using gutters made of galvanized steel installed on the soil surface and directed towards a container. The soil collected in the containers in each rainy event was filtered and dried in an oven at 45ºC for 5 days. With the drone, aerial images were obtained at the study site to build the Digital Terrain Model (MDT), which was used to prepare the Accumulated Flow maps using the GRASS complement in the QGIS software. At the end of all collections, the following response variables were evaluated: grams of soil (g); grams of soil per millimeter of rain (g mm-1); grams of soil per rainfall intensity (g mm-1 h-1); and grams of soil per square meter (g m-2). Total soil losses were determined using the Accumulated Flow map to identify the contribution area at the soil collection points and subsequently transformed into Kilograms per hectare (Kg ha-1). The results obtained in this work demonstrate that the high spatial resolution of the MDTs obtained with the Drone directly interfere with the results of the hydrological models constructed and soil losses in both crops tended to be influenced by the vegetation and rainfall coverage index and allows us to conclude that the The portable collectors used, associated with the use of Drone and GRASS GIS, are efficient for assessing soil losses due to water erosion in annual crops under natural conditions.