大豆和玉米生长对土壤N2O排放的影响

测定了盆栽试验条件下大豆和玉米生长期间的土壤N₂O排放。种大豆土壤的N₂O排放总量是相同条件下裸土排放总量的5.9倍，在大豆出苗后89 d里，种豆土壤的N₂O排放平均速率显著低于裸土，此后种豆土壤的N₂O排放速率显著高于裸土，种豆土壤N₂O排放总量的93%发生在只占全生育期24%的成熟衰老期。种玉米土壤的N₂O排放峰值出现在玉米出苗后13 d，而裸土的N₂O排放峰值出现在玉米出苗后81 d，裸土的N2O排放总量是种玉米土壤N₂O排放总量的13.5倍；种玉米土壤N₂O排放主要发生在前一半时期里，而裸土的N₂O排放主要发生在后一半时期里。无论在大豆还是玉米生长期间，裸土的N₂O排放速率均与气温呈极显著的正指数相关，而种豆土壤的N₂O排放速率与气温呈极显著的负相关，种玉米土壤的N₂O排放速率与气温没有显著相关性。由此可见，植物生长和植物类型不仅影响土壤N₂O排放的数量，也影响土壤N₂O排放与温度之间关系。

Effect of Soybean and Maize Growth on N2O Emission from Soil

The N₂O emission from soil was measured during the growth of soybean and maize in a pot experiment. During the period of soybean growth, the total N₂O emission from soybean-planted soil was 5.9 times as high as that from bare soil, but within 89 days after soybean emergence, the average rate of N₂O emission from planted soil was lower and thereafter was gradually significantly higher than that from bare soil. The N₂O emission from soybean-planted soil in the period of the ripening stage accounted for 93 percent of the total N₂O emission during the entire growth period, while the duration of ripening stage was only 24 percent of the soybean entire growth period. During the period of maize growing, the peak rate of N₂O emission from bare soil occurring at 81 days after maize emergence was significantly higher than that from maize-planted soil occurring at 13 days after maize emergence, and the total N₂O emission from bare soil was 13.5 times as high as that from maize-planted soil. The N₂O emission from maize-planted soil during the early halftime of the growth accounted for about 75 percent of the total N₂O emission, but that from bare soil during the later halftime was about 83 percent of the total N₂O emission. During both soybean and maize growth periods, the rate of N₂O emission from bare soil was significant exponentially correlated to air temperature, but there was a negative significant correlation between the rate of N₂O emission from soybean-planted soil and air temperature, while the correlation of N₂O emission rate from maize-planted soil to air temperature was insignificant. The results indicated that plant growth and species influence not only the quantity of N₂O emission from soil, but also the relationship between N₂O emission from soil and air temperature.