Complementary use of geo-chemical fingerprints and fallout radionuclides to evaluate the impacts of livestock and agricultural practices on soil erosion processes in a semi-arid region of central Argentina

Abstract

This study focuses on the complementary application of two innovative techniques: a) the use of geo-chemicalelements as fingerprints to investigate sediment transport and b) to compare the values of 137Cs soil inventoryin an Argentinean site with respect to the local reference value to quantify erosion or sedimentation processes(137Cs technique). The main aim is to evaluate the impacts of land degradation due to agricultural practicesimplemented in recent decades in a semi-arid region of the Province of San Luis in Central Argentina.Phosphorus, iron, calcium, barium, and titanium as well as the total organic carbon content were applied foridentifying critical hot spots of erosion in the studied catchment. Feedlots were identified as one of the mainsources of sediments together with river banks, dirt roads and livestock grazing. Additionally, the comparisonof 137Cs soil inventory in agricultural sites versus an undisturbed reference site (330 Bq m-2(SD: 54 Bq m-2))highlighted that the agricultural practices, based on direct seeding without plowing, constitutes an advisablepractice to minimize the loss of surface soil.