旱区覆膜滴灌棉田N 2 O排放对化肥减量有机替代的响应

覆膜滴灌条件下,采用静态箱-气相色谱法研究了不同施肥策略:CK(不施肥)、CF(N 300 kg/hm~2;P2O590 kg/hm~2;K2O 60 kg/hm~2)、60%CF+OF(普通有机肥6 000 kg/hm~2)、60%CF+BF(生物有机肥6 000 kg/hm~2)对棉田土壤N_2O排放的影响,旨在明确滴灌棉田连续不同施肥策略下土壤N_2O的排放特征。结果表明,棉花生育期N_2O排放通量表现为施肥处理大于不施肥处理,滴灌施肥后第3/4天N_2O排放通量顺序为CF60%CF+OF60%CF+BFCK,而滴灌后第7/8天N_2O排放通量则表现为有机肥处理高于化肥处理,滴灌施肥结束后表现与之相同;生育期的N_2O排放总量以100%化肥处理(CF)最高,与其相比,60%CF+OF和60%CF+BF处理分别降低3.75%和8.37%,N_2O排放系数则分别降低1.39%和73.8%;相关及通径分析均表明,与土壤NH+4-N相比,NO-3-N与N_2O排放的关系更密切。

Response of Soil N 2O Emission to Partial Chemical Fertilizer Substituted by Organic Fertilizer in Mulch-drip Irrigated Cotton Field

The effects of combining organic fertilizer with chemical fertilizer on cotton field N 2O emission flux, emission characteristic and total amount of N 2O emission were investigated by using the static chamber-gas chromatograph method under plastic-mulched drip irrigation. The four-year field experiment consisted of four treatments, including CK, CF, 60%CF+OF and 60%CF+BF (without fertilization as CK, total chemical fertilizer as CF, organic fertilizer as OF and bio-organic fertilizer as BF). The results showed that N 2O emissions with fertilizer supply were significantly higher than that without fertilizer treatment during the growing season of cotton. The order of N 2O emission on the third or fourth days after fertilization was: CF > 60%CF+OF > 60%CF+BF > CK, and a significant difference existed between treatments ( P <0.01) during each fertigation schedule with drip irrigation system. However, treatments with organic fertilizer combined with chemical fertilizer increased N 2O emission compared with chemical fertilizer treatments on the seven or eighth days after fertigation. In addition, when all irrigation and fertilization schedules were finished, higher N 2O emission flux was always observed with treatments supplied with organic fertilizer in contrast to that with chemical fertilizer application. The highest amount of total N 2O emission in the cotton growing season was found in CF treatment. Compared with CF, the treatments of 60%CF+OF and 60%CF+BF decreased N 2O emission by 3.75% and 8.37%, respectively. It was found that N 2O emission factor (EF) was also decreased by 1.39% with 60%CF+OF treatment and by 73.8% with 60%CF+BF treatment. Meanwhile, path analysis showed that N 2O emission was more closely related to soil NO - 3-N content than to NH + 4-N content.