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.

TORRES ASTORGA, R; M. RIZZOTTO; L. MABIT; H. VELASCO

Panama

Congreso; 38th IAHR World Congress; 2019

IAHR

This study focuses on the complementary application of two innovative techniques: a) the use of geo-chemical elements as fingerprints to investigate sediment transport and b) to compare the values of 137Cs soil inventory in 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 practices implemented 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 for identifying critical hot spots of erosion in the studied catchment. Feedlots were identified as one of the main sources of sediments together with river banks, dirt roads and livestock grazing. Additionally, the comparison of 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 advisable practice to minimize the loss of surface soil.