Nitrogen availability, maturity and stability of bokashi-type fertilizers elaborated with different feedstocks of animal origin

Organic amendments, such as bokashi, are applied to the soil to increase the N. However, the available N provided by these fertilizers and the feedstocks with which they are produced have been poorly documented. In this work, the available N in bokashi was evaluated as well as their biological stability and chemical maturity. The treatments bokashi poultry (WVP); bokashi swine (WVS) and bokashi control (WVC) contained wheat straw and vegetable wastes; WVP and WVS also included poultry and swine manure, respectively. The temperature, mineral N, pH, EC, CO2 production rate and germination index (IG) were measured. At the end of the trial, all of the treatments' temperatures exceeded room temperature. The WVP presented a higher mineral N (1,054 mg kg(-1)) than the WVS (844 mg kg(-1)) and the WVC (907 mg kg(-1)). In all treatments, the NH4+ and NO3- decreased. EC reached phytotoxicity levels in all treatments (EC > 3 dS m(-1)). None of the treatments showed biological stability or chemical maturity (IG of WVP, WVS and WVC: 10%, 29% and 19%, respectively). Therefore, it is concluded that applying these bokashi to soils could limit crop growth due to phytotoxic effects and immobilization of transient N.