Effect of no-tillage on the organic fractions and other chemical properties in soils of the argentine pampas

DUVAL M; GALANTINI, J; WALL, L; MARTINEZ, JM; IGLESIAS, J; CANELO, S

Montevideo

Conferencia; XXIX Conferencia Mundial ISTRO y IV Reunión SUCS; 2012

ISTRO de Uruguay, la Sociedad Uruguaya de Ciencias de Suelos (SUCS), la Facultad de Agronomía de la Universidad de la República Oriental del Uruguay y el Instituto Nacional de Investigación Agropecuaria (INIA)

Soil organic matter (SOM) is one of the most important components of the soil. It is composed of several fractions with different lability, like particulate organic carbon (POC) and carbohydrates (CH). These fractions are more sensitive to changes due to the management practices than the recalcitrant ones. The aim of this study was to analyze different soil parameters to found sensitive indicators for the evaluation of different management practices on sites with different soil and climatic conditions. The areas investigated were located in Monte Buey (Cordoba), Bengolea (Cordoba) and Pergamino (Buenos Aires). Three treatments were defined according to land use: ?Good management? (GM): sustainable agricultural management under no-tillage (NT); ?Bad Management? (BM): Non-sustainable agricultural management under NT; ?Natural Environment? (NE): rangelands long as reference situation. The soils were sampled at 0.00-0.05, 0.05-0.10, 0.10?0.15 and 0.15?0.20 m depth and analyzed for total organic carbon (TOC), total and soluble carbohydrates (CHt and CHs, respectively). The decrease of TOC due to changing land use of natural systems to cultivated was 25 and 35% for GM and BM, respectively, while differences between agricultural systems were 11, 14 and 20% for Bengolea, Monte Buey and Pergamino, respectively. The CHs and CHt contents showed similar differences than those observed in TOC for Bengolea, however, for the other 2 sites, marked differences were found. Farming systems decrease 30 and 60% CHs content in GM and BM, respectively. The results showed higher sensitivity to management practices of CHt and CHs, proportionally more affected by management practices, than TOC, because of this, they would be consider as a good indicator of changes in soil quality.