Contribution of leaves in the recycling process of N and P in Eucalyptus sp.

Abstract

The contribution of leaves in the recycling process of N and P was evaluated under two types of plantation: Eucalyptus globulus located in the Central Valley of Chile, and Eucalyptus nitens located in the Pre-Andean sector. Both geographical areas are located at the VIII Region of Chile (Southern region). The methodology of the study consisted of monthly quantification of fallen leaves proceeding from both fertilized and unfertilized trees during the initial three years of growth. At the end of the second year of growth, the biomass pertaining to the fallen leaves varied from 93 to 354 kg ha - 1 in unfertilized trees. The range of biomass increased to 482 - 984 kg ha - 1 in the case of fertilized trees. In the third year, values in the order of 2113 - 3570 kg ha - 1 were reached in unfertilized trees, and 3841 - 6978 kg ha - 1 in fertilized trees. Leaf fall took place mainly in spring and during periods of high water stress in summer. In this case, the supply of N varied between 29 and 46 kg N ha - 1 in the fertilized trees. At the time of leaf fall, the leaves showed a low concentration of N and P due to redistribution of these nutrients to other parts of the plant. The redistributed amount was estimated as 72 - 130 kg N ha - 1 and 3.0 - 5.6 kg P ha - 1 in fertilized trees. Eucalyptus nitens produced the highest values in the pre-mountain range in the site with high water availability because a greater biomass of leaves was produced.