TEMPORAL VARIATIONS OF ORGANIC MATTER FRACTIONS OF DIFFERENT LABILITY IN AN ENTIC HAPLUSTOLL

ITURRI, LAURA A.; HEVIA, G.; DIAZ RAVIÑA, M.; BUSCHIAZZO, D. E.

Spanish Journal of Soil Science

Universia Publicaciones

Lugar: Madrid; Año: 2017

2253-6574

Stable and labile soil organic compounds play different roles in the soil. It is whether a question how far soil organic matter (SOM) fractions with different lability vary as a function of climatic and management conditions. In order to answer this question stable (organic C -C-, total N -N-, organic P -Po-), and labile SOM fractions (total carbohydrates -CHt- and hot water soluble carbohydrates -CHw-) were monthly measured along two years on the 10-cm soil top-layer of an Entic Haplustoll, under conventional tillage (CT), vertical tillage (VT) and no-till (NT). Results showed that contents of all analyzed organic fractions were higher in NT than in VT and CT in almost all sampling dates. All organic compounds were less variable with time in NT and VT than in CT, in agreement with the lower soil disturbing of NT and VT than in CT. The more labile fractions varied as a function of short term changes in the climatic conditions, mainly temperature. Under tillage systems including soil disturbing, the most stable fractions tended to decrease and the more labile to increase with time. This was attributed to the transformation of the more stable into the more labile fractions, possibly due to the disruption of aggregates produced by tillage which favored SOM mineralization. Po was the less variable compound, even under highest disturbing tillage conditions. The quotients C/N, CHt/C and CHw/C evolved similarly in all tillage systems, indicating that that tillage systems change the amount but not the quality of SOM.