Estoque de carbono no solo e em frações da matéria orgânica com o uso de dejetos e fertilizante mineral, a longo prazo sob plantio direto

Abstract

Effect of animal manure use in soil is most diverse and has great importance, which is influenced directly or indirectly by carbon (C) added to soil. In Brazil, there is a lack of information in long - term experiments comparing effect of manures types and mineral fertilizer on soil organic carbon (SOC) stock and in labile and stable fractions of soil organic matter (SOM). The objective of this work was to investigate the impact of successive long-term applications of manure and mineral fertilizer over 12 years on soil C stock and physical fractions of SOM. The study was conducted in an experiment from 2004 to 2016 in Santa Maria, Rio Grande do Sul, Brazil. The treatments consisted of application of Mineral Fertilizer (MF); Pig Slurry (PS); Cattle Slurry (CS); Pig Deep Litter (PDL) and Control, without fertilization (Cont). C stock in soil profile (0-70 cm) was quantified after 4 and 12 years, and the C stock in free light fraction (FLF), occluded light fraction (OLF), particulate (Part) and associated to silt and clay (S + C) of SOM after 12 years. Manure use yielded higher increases in C stock in soil and in SOM fractions in relation to MF. These effects were verified up to 10 cm, and were more marked with the use of PDL and CS. PDL and CS use in long term increases C stock in soil and favors SOM protection by C accumulation in organo-minerais complexes and C occlusion in aggregates. This suggests that C derived from of PDL and CS are relatively stable and of great importance in SOM stabilization.