ABSTRACT

Studies related to erosive processes are an extremely important issue nowadays, due to its environmental and economical impacts. The erosive processes were related to suction and monitored in four different land management scenarios (olericulture with conventional tillage, pasture, forest recovery area and native forest) in an agricultural region in the mountainside of Rio de Janeiro, Brazil. Suction was measured using the filter paper method directly in situ, which confirmed to be simple, low-cost and efficient. Field work required a large number of filter papers, in which many were of different batches. For practical purposes, just one calibration curve (Chandler et al. 1992) was used, despite research work advice calibration for different batches of filter paper (Marinho & Oliveira 2006). Electron microscope scanning images of filter paper from the same and different batches were processed to observe its intrinsic properties. In the same batch different characteristics were observed using the electron microscope scanning, what did not produce significative differences in the behavior of the filter paper. Also, two different sizes of filter paper, smaller than the usual, adapted to the equipment developed to measure the total suction were used in the field experiments. The size of the filter paper used did not influence significantly the results. Total suction measurements were made in the four experimental plots during six months using the filter paper method in situ. This paper also presents the procedure used to measure the suction in the field. The results were well correlated with precipitation events data. Finally, characteristic curves were obtained using the filter paper method in laboratory to have better knowledge of the erosive and suction processes. The results were compared with the Fredlund SWCC Device® showing good correlation.