Abstract
A trial testing different regionally available organic fertilizers was established in 2018 in an organic apple orchard. Vinassa, clover pellets, horn shavings or a biodigestate were tested as the source of nutrients. Standard manure fertilization and no fertilization were considered as control treatments. To evaluate the effect of those treatments on the macroelements availability in soil the levels of nitrogen (N-NO 3), phosphorus (P) and potassium (K) were monitored during the trial. Furthermore, the products underwent a mineralization experiment to test the dynamic of N release. The studied products had different N mineralization rate which was paralleled by different soil availability. The biodigestate showed the fastest mineralization and also soil availability. Vinassa and the horn shavings appeared to have a steady N release dynamic and nutrients availability throughout the season. The clover pellet resulted to have a negative N mineralization rate up to 30 days, with limited N availability in the soil. A preliminary possible strategy in using the different formulations is proposed to match with plant nutrient needs and to increase soil nutrient content.