Changes in soil erosion associated with the shift from conventional tillage to a no-tillage system, documented using 137Cs measurements.

摘要

Caesium-137 measurements have been used to document changes in the rate and extent of soil erosion associated with the shift from conventional tillage to a no-till system on a farm in south-central Chile. The study site is located in the Coastal Mountains of the 9th Region (38 degrees 37'S 73 degrees 04'W), and is characterized by Araucano series Ultisols (Typic Hapludult), a temperate climate and a mean annual precipitation of 1100 mm year-1. A field, which was under conventional tillage until May 1986 and which was subsequently managed using a no-till system, was selected for the study. An approach for using 137Cs measurements to quantify the medium-term erosion and deposition rates associated with the periods of contrasting land management documented previously was employed. This approach involves both a standard method and a simplified method, which permits a larger number of sampling points to be used. In this study, emphasis was placed on application of the simplified method, which has the important advantage of requiring only two 137Cs measurements per sampling point. The results obtained for the study field showed that the implementation of no-till practices, including crop residue management, coincided with a reduction in the net erosion rate by about 87% and the proportion of the study area subject to erosion from 100% to 57%, and therefore significantly decreased soil and nutrient loss. Reduced soil and nutrient loss has important on-site benefits, in terms of sustainable management of the soil resource and maintaining crop productivity, as well as reducing off-site problems associated with the degradation of river water quality..