Decomposition of chestnut litterfall and eight-year soil chemical changes under a no-tillage management system in Northern Portugal.

摘要

Chestnut stands (Castanea sativa Mill.) for fruit production, in Northern Portugal, are subjected to frequent soil tillage operations, which is considered a threat for the system sustainability. The effects of replacement of conventional tillage by the no-tillage system in chestnut stands on decomposition and nutrient dynamics of leaf litter and burs were evaluated, using the litterbag methodology. Amounts of mass and nutrients in the organic layers, and chemical characteristics of the 0-20 cm top soil layer were assessed after eight years. The mass loss and release of N, P, Ca and Mg from both leaves and burs buried in the soil were faster than from those placed on the soil surface. Burs decomposed and released nutrients more slowly than leaf litter. The no-tillage system led to the formation of organic layers, which retained great amounts of N (249.2 kg ha-1) and Ca (215.5 kg ha-1). Such a management system increased the concentration of organic C and nutrients in the 0-5 cm top soil layer, but significant differences were only observed for exchangeable Ca. The no-tillage system may enhance organic C accumulation regarding the conventional system, due to the increment in both organic and mineral soil layers.