Autumn Leaf Litter and Its Biochar Amendment on Soil Nitrous Oxide Emission, Plant Growth, and Nutrient Uptake of Komatsuna and Spinach Grown in Potted Soils

A pot experiment was conducted to assess the effect of fallen leaf litter and its biochar amendment on vegetable growth and N2O emissions from two successive vegetable crops. Four treatments; 1) control (no amendment), 2) leaf litter, 3) leaf litter biochar, and 4) combination of leaf litter and biochar were established before planting the first crop (komatsuna) but no additional amendment was done for the second crop (spinach) to assess the residual effects of the treatments. The results showed that application of leaf litter either alone or combined with biochar significantly decreased vegetable yields and nutrient uptake while increasing N2O emissions from both crops. Conversion of leaf litter to biochar and its amendment showed no significant differences in vegetable yield, but nutrient uptake was improved when compared with the control. Biochar amendment significantly reduced soil N2O emission in the first crop but no significant effect was observed in the successive spinach crop although the amount emitted was less compared with the control. Therefore, conversion of municipal leaf litter to biochar and its amendment to vegetable soils will be one of the best solutions for reducing soil N2O emission while maintaining vegetable yield.