摘要：An important source of the destructive greenhouse gas, nitrous oxide (N
2O) comes from the use of ammonium based nitrogen (N) fertilizers that release N
2O in the incomplete conversion (nitrification) of NH
4
+ to NO
3ˉ
1. Biochar has been shown to decrease nitrification rates and N
2O emission. However, there is little information from semi-arid environments such as in Pakistan where conditions favor N
2O emissions. Therefore, the object was to conduct field experiment to determine the impact of biochar rates in the presence or absence of urea amended soils on yield-scaled N
2O emissions, and wheat yield and N use efficiency (NUE). The experiment on wheat (
Triticum aestivum L.), had a randomized complete block design with four replications and the treatments: control, sole urea (150 kg N ha
−1), 5 Mg biochar ha
−1 (B5), 10 Mg biochar ha
−1 (B10), urea + B5 or urea + B10. In urea amended soils with B5 or B10 treatments, biochar reduced total N
2O emissions by 27 and 35%, respectively, over the sole urea treatment. Urea + B5 or + B10 treatments had 34 and 46% lower levels, respectively, of yield scaled N
2O over the sole urea treatment. The B5 and B10 treatments had 24–38%, 9–13%, 12–27% and 35–43%, respectively greater wheat above-ground biomass, grain yield, total N uptake, and NUE, over sole urea. The biochar treatments increased the retention of NH
4
+ which likely was an important mechanism for reducing N
2O by limiting nitrification. These results indicate that amending soils with biochar has potential to mitigate N
2O emissions in a semi-arid and at the same time increase wheat productivity.
