TP5: Biomass quality
Quality of in- and outputs of crop and tree biomass in agroforestry systems
In this subproject, we analyze the amounts and qualities of above-ground biomass inputs and the outputs of annual crops and perennial trees. Based on these results, we conduct spatial yield analyses of the annual crops. In doing so, the contribution of tree-specific inputs, such as the organic matter and nutrients of leaf litter, and tree-specific characteristics, such as rooting in deeper soil layers, to a sustainable and permanent increase in soil fertility in agroforestry systems will be assessed. Our field experiments are conducted at the agroforestry sites in Mariensee and Wendhausen. To determine the amounts and qualities of the above-ground biomass inputs, we measure and analyze the spatial distribution of leaf litter within the tree strips and in the crop alleys at different distances from the tree strip. Additionally, we determine decomposition rates of leaf litter in the top soil in the shaded and unshaded zones of the crop alley. At the Wendhausen site, we estimate the quantity and quality of harvest residues of the annual crops and determine their decomposition rates. To analyze the amounts and qualities of the above-ground biomass outputs, we estimate the yearly tree growth by measuring the diameters at breast height and tree heights. To quantify the value for bioenergy use, we determine water content and the nutrient concentrations of the trees. Trees are harvested every five or six years, depending on the rotation cycle. In the crop alleys, we quantify the crop yield at several distances from the tree strip. Additionally, we determine nutrient concentrations in grain and straw samples and record further quality parameters, such as thousand-grain-weight and protein content. On the basis of the determined amounts and qualities of above-ground biomass in- and outputs, we will map the spatial distribution patterns of crop yields in relation to the distance from the tree strips.