Urease Inhibitor NBPT on Ammonia Volatilization and Crop Productivity: A Meta‐Analysis

Abstract

Core Ideas The volatilization losses averaged 31.0% of applied N for urea and 14.8% for NBPT‐treated urea. NBPT‐treated urea showed a potential yield increase of 5.3% for major crops. The effect of NBPT in reducing volatilization losses were reduced under high N rates. NBPT had a limited effect on increasing yield in coarse‐textured soils and for NBPT rates >1060 mg kg−1. The urease inhibitor N‐(n‐butyl) thiophosphoric triamide (NBPT) slows urea hydrolysis, reduces NH3 volatilization loss, and enhances N availability to plants. Even though most studies have proved the potential of NBPT‐treated urea to reduce NH3 loss, the benefits to increase crop yield have been less consistent, mainly because N is not always the limiting factor. A meta‐analysis was carried out to evaluate the effect of soil properties (e.g., soil pH, soil texture, soil organic C [SOC]), N rate, and NBPT concentration on NH3 volatilization loss and crop yield when comparing urea with NBPT‐treated urea. Regression analysis indicated cumulative NH3 loss of 31.0 and 14.8% of applied N for urea and NBPT‐treated urea, respectively, a 52% reduction in NH3 loss by using the urease inhibitor. The use of NBPT delayed NH3 loss. It took 4.8 and 8.3 d for 50% of the total NH3 loss to occur for urea and NBPT‐treated urea, respectively. The meta‐analyses indicated that when compared with urea, NBPT‐treated urea reduced NH3 volatilization loss across all soil pH classes, soil texture classes, SOC contents, N rates, and NBPT concentrations. The meta‐analysis indicated an average crop yield increase of 5.3% for NBPT‐treated urea compared with urea. This trend was observed for all classes of soil pH, SOC content, and N rate, but yield increases were limited in coarse‐textured soils and NBPT rates >1060 mg kg−1.

Performance of nitrification inhibitors with different nitrogen fertilizers and soil textures

“…For the combination of N sources with NI, ASN combined with an NI was more efficient in keeping N as compared to UR in sand and loam‐textured soils. Urea hydrolysis promote soil pH to increase, reaching values up to 9.0 ( Clay et al., ; Gioacchini et al., ) near where the fertilizer has been placed ( Overrein and Moe , ), causing N losses by N‐NH 3 volatilization ( Silva et al., ). Soil from UR peaks in the initial days after application in all soils.…”

The molecular processes of urea hydrolysis in relation to ammonia emissions from agriculture

“…To obtain equivalent yields using urea fertilizer without NBPT, an additional 80 kg fertilizer per hectare was needed (Hendrickson and Douglass 1993). In general, it is difficult to estimate to what extent crop yield is influenced by the use of urease inhibitors due to the many different factors that determine the overall ammonia emissions and N-retention, but a recent meta-analysis found that the average cumulative ammonia loss was reduced by 52% (from 31.0% of applied N to 14.8%) and that the grain yield increased on average by 5.3% when synthetic urea fertilizer was amended with NBPT (Silva et al 2017). Marchesan et al noted that NBPT generally slowed the hydrolysis of urea to ammonia when applied to the rice crop compared to the urea fertilizer without NBPT, but the effectiveness was highly influenced by climate, type of soil, and moisture (Marchesan et al 2013).…”

Ammonia and carbon dioxide emissions by stabilized conventional nitrogen fertilizers and controlled release in corn crop

“…Results obtained by Cantarella et al (2008) showed that cumulative N-NH 3 losses of urea + NBPT were 7.2; 15.2; 21.3; 1.6; 13.4; 0.8 and 11.2% of the N applied to different locations and application times. Several studies have shown that the application of urea stabilized with urease inhibitors, such as NBPT, is associated with the reduction, at different intensities, in N-NH 3 loss by volatilization (Rawluk et al, 2001;Cantarella et al, 2008;Watson et al, 2008;Pereira et al, 2009;Grohs et al, 2011;Silva et al, 2016).…”