Changes in soil erosion associated with the shift from conventional tillage to a no-tillage system, documented using (CS)-C-137 measurements

Resumen:
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 (CS)-C-137 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 target-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 (CS)-C-137 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. (c) 2006 Elsevier B.V. All rights reserved.

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