The effects of rice rotation in summer on the nitrification and ammonia volatilization of soil under greenhouse vegetable cultivation were studied based on the comparison of soil nitrification intensity

ammonia volatilization rate and the index about soil hydrothermal condition during greenhouse eggplant cultivation between two different crop rotation systems

greenhouse eggplant-rice rotation (GER) and greenhouse eggplant-summer fallow without plastic covering (GEF). The results showed as follows: (1)The soil nitrification intensity in GER was significantly higher than that in GEF during the different growth period of eggplant. The nitrification intensities of surface soil and rhizosphere soil on the seeding stage in GER were 56.6 mg/(kg·h) and 101.4 mg/(kg·h)

with the increases of 34.8% and 42.4% compared with GER

respectively. (2)The soil ammonia volatilization rate and accumulative ammonia volatilization amount in GER were significantly lower than those in GEF. The gross ammonia volatilization amount of GER was 1.21 kg/hm2

with the decrease of 76.7% compared with GEF. (3)The NH4+-N amounts of surface soil and rhizosphere soil in GER were lower than those in GER during the different growth period of eggplant

whereas the NO3--N amounts in GER were higher than those in GEF. (4)The NH4+-N amounts of surface soil in GER and GEF after eggplant harvest were 30.4 mg/kg and 45.9 mg/kg

respectively

while the NO3--N amounts in GER and GEF were 265.4 mg/kg and 255.5 mg/kg

respectively

indicating the significant accumulation of nitrogen. The rice planting in summer alleviated the soil acidification and increased the pH

temperature and water content of soil during the greenhouse eggplant cultivation period. This also increased the nitrification intensity and decreased the loss of ammonia volatilization. However

the increase of nitrification intensity caused soil nitrate accumulation. This might lead to secondary salinization and nitrogen loss in soil. Therefore

the rational application of nitrogen fertilizer should be more concerned during the whole rotation period.