Land use impact on chemical and spectroscopical characteristics of soil organic matter in an arid ecosystem

VÁZQUEZ CAROLINA; IRIARTE ANA; MERLO CAROLINA; ABRIL ADRIANA; KOWALJOW ESTEBAN; MERILES JOSÉ

Environmental Earth Sciences

Springer Berlin Heidelberg

Lugar: Berlin; Año: 2016 p. 883 - 883

1866-6280

Soil organic matter (SOM) storage and composition in ecosystems may undergochange as a result of long-term livestock and soil cultivation, particularly in aridenvironments. In this work, we evaluated the alterations produced in both the quantityand quality of SOM due to productive management systems. The impact of land usechange on SOM, dissolved and hot water-extractable carbon (DOC and HWC), humicsubstances (HS), humic acids (HA), fulvic acids (FA) and the infrared and visiblespectroscopy of HS were studied at three productive sites: total and selective clearingswith livestock (TC-livestock and SC-livestock), total clearing with irrigated agriculture(TC-agriculture), and an undisturbed site located in central-western Argentina. TheSOM content was higher at the undisturbed and TC-agriculture sites. DOC variedamong the study sites only during the dry season, while HWC decreased during thewet season, clearly indicating the lability of this fraction. The concentrations of HS, HA,and FA were reduced (50-75%) by land use change, with the HS compositiondetermined by Infrared Spectroscopy reflecting a high quantity of polysaccharides inTC-agriculture, while the E4/E6 ratio (UV-vis) presented low values at the undisturbedsite, indicating a high degree of condensation of aromatic substances. In conclusion, a)the conversion of native woodlands to livestock systems favored soil C losses, b) thehighest SOM storage recorded in TC-agriculture may reflect a greater residueaccumulation at the soil surface and c) the combination of different techniquesprovided a very good insight into the status of soil degradation.