Biochar and urease inhibitor mitigate NH3 and N2O emissions and improve wheat yield in a urea fertilized alkaline soil

Khadim Dawar,Syed Sartaj Alam,Subhan Danish,Muhammad Adnan,Aamir Khan,Ishaq Ahmad Mian,Jan Banout,Mohammad Javed Ansari,Muhammad Habib-Ur-Rahman,Shah Fahad,Raf Dewil,Shah Alam Khan,Iqbal Munir,Shah Saud,Muhammad Nauman Ahmad,M M R Jahangir,Rahul Datta

doi:10.1038/s41598-021-96771-0

Abstract

In this study, we explored the role of biochar (BC) and/or urease inhibitor (UI) in mitigating ammonia (NH3) and nitrous oxide (N2O) discharge from urea fertilized wheat cultivated fields in Pakistan (34.01°N, 71.71°E). The experiment included five treatments [control, urea (150 kg N ha−1), BC (10 Mg ha−1), urea + BC and urea + BC + UI (1 L ton−1)], which were all repeated four times and were carried out in a randomized complete block design. Urea supplementation along with BC and BC + UI reduced soil NH3 emissions by 27% and 69%, respectively, compared to sole urea application. Nitrous oxide emissions from urea fertilized plots were also reduced by 24% and 53% applying BC and BC + UI, respectively, compared to urea alone. Application of BC with urea improved the grain yield, shoot biomass, and total N uptake of wheat by 13%, 24%, and 12%, respectively, compared to urea alone. Moreover, UI further promoted biomass and grain yield, and N assimilation in wheat by 38%, 22% and 27%, respectively, over sole urea application. In conclusion, application of BC and/or UI can mitigate NH3 and N2O emissions from urea fertilized soil, improve N use efficiency (NUE) and overall crop productivity.

Highlights

In this study, we explored the role of biochar (BC) and/or urease inhibitor (UI) in mitigating ammonia (NH3) and nitrous oxide (N2O) discharge from urea fertilized wheat cultivated fields in Pakistan (34.01°N, 71.71°E)
The plots treated with biochar + urea showed maximum soil NH4+-N concentration 28 days after fertilization, which was significantly higher than the plots treated with sole urea (Fig. 1)
The results showed lower N H4+-N concentrations in plots treated with urea + BC + UI than sole urea treated plots, while N O3-N concentrations were higher in urea treated plots than in urea + BC + UI (Fig. 1 and Fig. 3)

Summary

Results

The NH4+-N concentration observed in urea treated plots on day 1 was significantly (p < 0.05) higher (5–25 mg N kg−1 soil) compared to the control (Fig. 1). The plots treated with biochar + urea showed maximum soil NH4+-N concentration 28 days after fertilization, which was significantly higher than the plots treated with sole urea (Fig. 1). The application of urea, BC, and UI significantly affected the daily and cumulative N2O emissions (Fig. 3 and Table 2). Wheat N uptake, yield and NUE were significantly improved due to biochar and/or UI application (Table 3). The highest total N uptake, above ground wheat biomass, contained 101 and 114 kg N ha−1 from urea + BC and urea + BC + UI treated plots, respectively (Table 3). The NUE observed for sole urea, urea + BC and urea + BC + UI were 27%, 35%, and 43%, respectively (Table 3)

Discussion

Conclusions

Materials and methods