Effects of different fertilizer and irrigation levels on N₂O emission from greenhouse vegetable lands

In order to evaluate N2O emission from greenhouse vegetable production system and its mitigation potential, a field experiment was conducted in Beijing in 2011. There were two factors, irrigation and fertilizer in the experiment. The irrigation included high input level (H) and low input level (L), and every irrigation level contained three fertilizer levels, high fertilizer input(N1), low fertilizer input(N2) and no fertilizer(CK). The results show that the cabbage yields have no significant differences between the irrigation levels, while the yields from the high fertilization treatments are significantly higher than those of the low fertilization level treatments. The N2O emissions mainly appear at the beginning after the organic fertilizer application, and then decrease gradually. The N2O emissions in the first month after the fertilizer application accounts more than 80% of the total emissions in the whole growing season. The N2O emission peaks just after each irrigation, and the N2O emissions from the high irrigation treatments are higher than those of the low irrigation treatments. The high fertilizer input increases the N2O emission compared with the low fertilizer treatments and both of them are significantly higher than that of the control. The N2O emission factors are averagely between 0.29%-0.39% of the fertilized treatments.