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

ABSTRACT

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.

KEYWORDS:

• Organic matter
• nitrogen supply
• mineral nitrogen
• swine manure
• poultry manure

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by Dicyt Project N° 091675QE, Vicerrectoría de Investigación y Desarrollo, University of Santiago de Chile, Usach.