Urease Inhibitor N-(n-butyl) Thiophosphoric Triamide (NBPT) Application as a Mitigating Strategy of Ammonia Volatilization from Different Loess Soils of China

The use of urease inhibitors (UIs) has been proposed to reduce nitrogen (N) losses, including ammonia (NH₃) volatilization from N fertilizers applied soils. However, the effects of soil properties on UIs efficiency for mitigating NH₃ emissions remains less clear.

An incubation study was conducted, to evaluate the efficiency of urease inhibitor N-(n-butyl) thiophosphoric triamide (NBPT) on NH₃ volatilization. The soils were used from six different counties (Zhouzhi, Yangling, Changwu, Luochuan, Ansai and Shenmu) of the Loess Plateau, China characterized different soil properties. The treatments were control (no N), urea (0.2 g N kg^− 1 soil) and urea + 0.5% NBPT.

The cumulative NH₃ volatilization loss in urea applied six different soils were 42.8–56.1 mg kg^− 1 (21.4–28.1% of N applied). The NH₃ emission rate rapidly increased in Shenmu, Ansai and Luochuan soils and recorded highest (28.1, 27.1 and 25.8% of N applied), probably due to more sand particles and higher soil pH. In contrast, Zhouzhi, Changwu and Yangling soils showed gradual increase in NH₃ emission rate and recorded lowest (21.4, 21.5 and 23.2% of N applied), might be due to more clay particles and low soil pH. Urea + 0.5% NBPT delayed urea hydrolysis and significantly reduced NH₃-N loss by 47.1–55.5% in different soils. The soil texture, pH, urease activity (UA), calcium carbonate (CaCO₃) and organic matter content were the main soil factors affected the rate of NH₃ volatilization and NBPT effectiveness.

This study validated that NBPT application has immense potential in mitigating NH₃ volatilization from different soils.