15N示踪法研究生物炭施用对油菜氮素吸收和转运的影响

以棕壤为供试土壤,采用15 N示踪法研究水稻稻壳制成的生物炭在不同用量(0,0.5%,1%,2%)下对连续种植两季油菜的土壤中氮含量、油菜产量、油菜地上及地下部分的吸氮量以及N2O气体损失的影响,并计算肥料氮的氮素利用率及其不同去向所占比例,探明生物炭施用对油菜肥料氮吸收及转运的影响。结果表明:(1)施加生物炭显著提高了第1季、第2季油菜的产量。(2)0.5%生物炭用量与对照相比,第1季油菜吸收土壤氮素的比例提高了2.0%;0.5%,1%,2%生物炭用量使第2季油菜吸收土壤氮素的比例分别提高了0.8%,2.4%,3.2%。第1季、第2季油菜叶和根对氮素的吸收随生物炭施用量的增加而增加。(3)与对照相比,施加生物炭处理显著降低了两季油菜N2O气体排放,2%生物炭用量使第1季、第2季N2O气体排放分别减少了0.30,0.10mg/kg。(4)2%生物炭用量处理与对照相比,第1季氮素利用率提高了16.3%;两季氮素利用率的结果显示,0.5%,1%,2%处理分别比对照提高了0.4%,0.7%,5.3%,其中以2%生物炭施用量效果最佳。

Effect of Biochar Application on Nitrogen Uptake and Transport in Rape by 15N Tracing Method

Using the brown soil as the tested soil, pot experiment was conducted to investigate the effects of biochar derived from rice husk on soil nitrogen content, rape yield, nitrogen contents of aboveground and underground of rape, and the loss of N₂O gas under two consecutive cropping seasons using ¹⁵N tracing method. Nitrogen utilization efficiency of nitrogen fertilizer and the proportion of different fate were calculated to study the effect of biochar addition on uptake and transport of nitrogen in rape. Biochar was applied at four rates (0, 0.5%, 1% and 2%) to the soil. The results showed that biochar application significantly increased the yield of rape in the first and the second cropping seasons. Compared with no biochar addition, the ratio of soil nitrogen uptake by rape was increased by 2% in the first season in the treatment of 0.5% biochar application, and it was increased by 0.8%, 2.4% and 3.2% in the second cropping season, in the treatments of 0.5%, 1% and 2% biochar application, respectively. The nitrogen contents of leaves and roots increased with the increasing of biochar application. Compared with no biochar addition, biochar application significantly decreased N₂O gas emission of rape in the two seasons, and the N₂O gas emission reduced amount was 0.30 and 0.10 mg/kg in the first season and the second season, respectively, in the treatment of 2% biochar application. Compared with no biochar addition, nitrogen utilization efficiency of rape increased by 16.3% in the treatment of 2% biochar application. The average nitrogen utilization efficiency of two seasons increased by 0.42%, 0.72% and 5.3% in the treatment of 0.5%, 1% and 2% biochar application, respectively. Thus, 2% biochar application should be considered as a suitable soil amendment.