轮作水稻对大棚土壤硝化作用和氮挥发的影响

通过大棚茄子—水稻轮作(GER)和大棚茄子—揭膜休闲(GEF)2种栽培模式在大棚茄子栽培期间土壤硝化作用强度、氨挥发速率和土壤水热条件指标动态变化的比较,研究了轮作水稻对大棚土壤硝化作用和氨挥发的影响。结果表明:(1)GER模式在大棚茄子各生育期土壤硝化作用强度都显著高于GEF土壤,苗期最高峰时表土和根际土硝化作用强度分别为56.6,101.4mg/(kg·h),比GEF模式增加了34.8%和42.4%;(2)GER模式在大棚茄子基肥和追肥施用后土壤氨挥发速率都显著低于GEF土壤,累积氨挥发量为1.21kg/hm~2,比GEF模式减少了76.7%;(3)GER模式在大棚茄子各生育期表土和根际土NH4+—N含量都低于GEF土壤,NO3-—N含量高于GEF模式;(4)GER和GEF模式在大棚茄子收获后表土NH4+—N含量分别为30.4,45.9mg/kg,NO3-—N含量分别为265.4,255.5mg/kg,存在明显的氮素累积。夏季轮作水稻缓解了大棚土壤酸化、提高了大棚茄子生长期间土壤pH、温度和含水量,对大棚土壤硝化作用有明显的促进作用,可减少土壤氨挥发损失。但硝化作用强度的增加促进了土壤中硝酸根的累积,存在加剧土壤次生盐渍化和氮损失的风险,应加强轮作周期氮肥合理施用技术研究。

Influence of Rice Rotation on Nitrification and Ammonia Volatilization of Soil under Vegetable Greenhouse Cultivation

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.