Objective This study aimed to achieve recycling of soy sauce residue oil, reduce its environmental pollution, and expand the resources of slow-release fertilizer material.

Method Coated nitrogen fertilizer was prepared by epoxy modification of soy sauce residue oil.The structure of the coated film was analyzed by infrared spectroscopy, high-power microscope and scanning electron microscope.The fertilizer efficiency was examined in corn pot experiment.

Result After epoxy modification of the soy sauce residue oil, its structure changed which promoted forming of film with dense net structure.In corn pot experiment, there were no significant differences in leaf number and chlorophyll content between the test group using coated nitrogen fertilizer (T1) and the control group with normal fertilization (CK2).The final leaf area, stem girth and plant height of T1 were significantly different from those of the control group with no fertilization (CK0) and the control group with only phosphorus and potassium but no nitrogen fertilization (CK1), and increased by 9.5%, 4.3% and 7.3% at 60 days respectively compared with CK2.The corn plant fresh weight of T1 was significantly different from those of the other three groups.While the corn plant dry weight of T1 was not significantly different from that of CK2, it significantly increased by 14.2% and 5.2% respectively compared to CK0 and CK1.

Conclusion Coated nitrogen fertilizer could promote maize growth, and is considered slow-releasing in soil.