Abstract:

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.

Key words: Soybean, Maize, Growth, N₂O emission from soil, Air temperature