Efecto residual del encalado y de la fertilización con lodos de depuradora urbana sobre los diferentes componentes de un sistema silvopastoral establecido con Pinus radiata D. Don en Galicia

Abstract

Silvopastoral systems should aim to optimize production of a tree component and crops and/ or animals within the same land-management unit. The aim of this study was to evaluate the effects of lime and two dose of sewage sludge applied in three dates on productivity and carbon sequestration in soil, pasture and tree in a silvopastoral system reforested with Pinus radiata D. Don. The results obtained showed that lime and sewage sludge inputs (high dose), caused an improvement of the soil edaphic conditions, without a negative impact derived from the accumulation of heavy metals. Initially, lime applications increased pasture-tree competition, however later we detected a recovery of the forest species in limed plots which received contributions of high dose of sewage sludge. A clear interaction between the dose and the date of application of sewage sludge was observed. Early fertilization with high dose caused a reduction of tree growth, due to increase of the development of herbaceous species. On the contrary, the later inputs of high sewage sludge dose increase the initial tree growth and shrub species, being this date more favourable for the tree growth than to the development of herbaceous pasture. The soil was the component of the silvopastoral system that mostly contributed to carbon sequestration followed tree component.