Inhibitory Effects of Aqueous Extracts from Leaves of Common Tropical Green Plants on Urea Hydrolysis in Soils

Abstract

Tropical plants contain a variety of secondary metabolites, and plant aqueous extracts can be used as urease inhibitors to improve nitrogen use efficiency and reduce the negative environmental effects. An incubation experiment was carried out to investigate the effects of aqueous extracts of 32 common tropical green plant species from 24 families on urea hydrolysis. The results indicated that the aqueous extracts from 3 of the common tropical green plants (Pterocarpus indicus, Callistemon rigidus, Terminalia mantaly) belonging to Leguminosae, Myrtaceae and Combretaceae respectively showed better inhibitory effects on urease than hydroquinone as a chemical inhibitor, and had more obvious potential applications. The inhibitory effects of active substances in plants were affected by extract temperature causing by solubility and thermal stability of active substances. T. mantaly had the most potential for development in this study as a fertilizer additive. The inhibitory effects of aqueous extracts of T. mantaly leaves on urea hydrolysis increased with increasing concentration of aqueous extracts, the strongest inhibitory effect on urease occurred after 2-3 d of incubation.