Litter decomposition is a key process in biogeochemical cycles of trees ecosystems and has a role both at local and at global scale because of his ruling the site fertility, nutrient availability and the carbon- sink potential of the system. It is defined as the ensemble of all physicals, chemical and biological mechanisms that lead the organic matter transformation in more stables forms. In orchards, abscised leaves, pruning wood and root turnover annually return to the soil significant amount of biomass and nutrients. In addition, mowed grasses from the orchard alleys contains significant amounts of nutrients which, if moved along the tree rows can significantly affect the nutrient availability for trees. Litter decomposition is a limit-value process split in two mains stages each characterized by different decay rates and different factors ruling the process. Basically these factors are the substrate quality, the type of decomposers and the environment (moisture, temperature, pH and soil texture). In the early stage the process is driven by nutrients abundance and climate, while later is adversely affected by nitrogen and lignin concentration. Ecological implications of the process concern mainly biogeochemical cycles of nutrients, both in terms of their availability and in terms of carbon balance of the whole ecosystem. Examples of nutrient release from decomposing leaves and pruning material as well as mowed grasses in orchards are given and their contribution to tree nutrition discussed.