草原土壤N_2O释放及全球变暖影响下土壤养分变化的反馈效应

N_2O emission from grassland soils and the teedback effect or nutrient changes resulting from global warming

对草原土壤Ｎ２Ｏ释放及其受全球变暖土壤养分变化的影响研究表明，以沼泽泥炭土Ｎ２Ｏ释放量最大，生长季节为１３～１２．２ｋｇＮ·ｈｍ－２·ａ－１，其次灰壤土，为１．５～２．４ｋｇＮ·ｈｍ－２·ａ－１，酸性棕壤最小，为０～３．２ｋｇＮ·ｈｍ－２·ａ－１；Ｎ２Ｏ的释放层灰壤土在０～５ｃｍ，其它２种土壤为０～１０ｃｍ；施肥试验表明，Ｎ、Ｐ肥在生长季节对土壤Ｎ２Ｏ释放量影响不显著，但在生长季末期，Ｎ肥对酸性棕壤及灰壤土Ｎ２Ｏ影响显著，施肥后第３天酸性棕壤由对照的１．３提高到４４．２ｋｇＮ·ｈｍ－２·ａ－１，灰壤土则由对照的１．９提高到３１．１ｋｇＮ·ｈｍ－２·ａ－１，说明全球变暖对土壤有机质分解的影响不会诱发Ｎ２Ｏ释放量的大幅度增加．

Studies on N2O emissions from grassland soils and its influence by nutrient changes resulting from global warming show that in growing season peaty gley soil has a maximtun N2O emission varying from 1. 3 to 12. 2 kg N· hm-2· yr-1, N2O emission in ndcropodzol soils is from 1. 5 to 2 .4 kg N·hm-2· yr-1, and acid brown earth has the lowest ranging from 0 to 3. 2 kg N·hm- 2· yr.- 1 . N2O emission mainly comes from top 5 cm in micropodzol soil, and from top 10 cm in other two soils. Fertilizer application in growing season doesn' t make any differece in different soils. However, N application greatly stimulates the N2O emission at the end of the growing season. And in acid brown earth and in micropodzol soil, it reached respectively 44. 2and 33. 1 kg N·hm- 2· yr.-1 compared to 1. 3 and 1. 9 kg N· hm-2· yr.-1 in the control. This implies that the influence of global warming upon decomposition of organic matters doesn' t result in a significant increase in N2O emission.