不同种类氮肥对土壤释放N2O的影响

用培养试验模拟研究了在正常水分(22%)、干旱(12%)和高含水量(32%)条件下,普通碳酸氢铵(普碳)、尿素及新型肥料长效碳酸氢铵(长碳)对土壤释放N₂O的影响;同时考察了土壤NO₃^-的形成时间和形成量.结果表明,农田中施加的无机氮肥是大气中N₂O的重要来源,而长碳与普碳和尿素相比,不但可以明显延后N₂O释放高峰期出现时间,而且大多数情况下可以显著减少其释放量(P<0.01).在5个月的监测期内,与普碳和尿素相比其减少N₂O释放的比例分别为80.23和88.41%(12%含水量),40.00和27.59%(22%含水量),无减少作用和45.88%(32%含水量).本研究结果提示长碳具有作为农田生态系统N₂O减排措施的巨大潜力,同时暗示在农业中用长碳代替目前普遍应用的普碳,可以减少地下水中NO₃^-引起的污染.

Effect of different nitrogen fertilizers on N2O emission from soil

Incubation experiments were made to study the effects of ammonium bicarbonate(AB), urea and modified ammonium bicarbonate(MAB) on N₂O emission from soil and NO₃^- formation in soil (under low(12%), normal(22%) and high (32%) soil moisture conditions). The results showed that the inorganic nitrogen fertilizers applied in fields were the important source of atmospheric N₂O. In most situations, MABnot only greatly delayed the occurrence of N₂O emission peak, but also reduced the amount of N₂O emission significantly (P<0.01), compared with ABand urea. In comparison with ABand urea, the amounts of N₂O emission were reduced by 80.23 and 88.41% (low moisture, 12%),40.00 and 27.59% (normal moisture, 22%) and little reduction and 45.88% (high moisture, 32%), respectively, during a period of 5 month incubation when MAB was applied. It is indicated that MAB was a promising Nfertilizer from the aspect of reducing N₂O emission from agroecosystem. The results also implied that applying MAB instead of AB which is used widely in China at present, might reduce the NO₃^- pollution of the underground water.