吡虫啉和毒死蜱对尿素氮在土壤中转化的影响

Effects of imidacloprid and chlorpyrifos on transformation of urea nitrogen in soil

为了考察杀虫剂施用对尿素态氮在土壤中转化过程的影响,采用室内培养法,通过测定土壤铵态氮和硝态氮质量分数以及反硝化损失的动态变化,研究了在施用尿素的土壤(有效氮含量为200 mg/kg)中分别添加不同剂量的吡虫啉和毒死蜱2种杀虫剂时,杀虫剂对尿素的水解、土壤氮的硝化及反硝化过程的影响。结果表明:吡虫啉和毒死蜱各剂量处理在第3天时对尿素水解具有显著的促进作用(P<0.05)。2种杀虫剂5 mg/kg的处理,在培养前期均显著促进硝化作用,第8天时吡虫啉和毒死蜱处理的硝化率分别比尿素处理提高了5.63和4.33个百分点,随后各处理间无显著差异;10 mg/kg吡虫啉的处理对硝化作用无明显影响,而毒死蜱则仅在第3天表现出显著的抑制作用(P<0.05);2种杀虫剂50 mg/kg的处理均显著抑制硝化作用(P<0.05),第8天时吡虫啉和毒死蜱处理的硝化率分别比尿素处理降低了5.18和8.69个百分点。吡虫啉各处理均能极显著地降低氮素的反硝化损失量(P<0.01),5、10、和50 mg/kg的处理分别比尿素处理的反硝化损失量减少36.98%、39.92%和68.54%;毒死蜱5和10 mg/kg处理对氮素反硝化损失无明显影响,但50 m/kg处理表现出极显著的抑制作用(P<0.01),减少反硝化损失量39.69%。

In order to assess the effects of pesticides on transformation of urea nitrogen in soil, indoor incubation experiments with 8 treatments including control, urea （200 mg/kg, a.i.,N dry soil）, urea （200 mg/kg, a.i.,N dry soil）＋imidacloprid （5, 10 and 50 mg/kg, a.i.,dry soil） and urea （200 mg/kg, a.i.,N dry soil）＋chlorpyrifos （5, 10 and 50 mg/kg, a.i., dry soil） were investigated. The dynamic variations of NH4＋-N, NO3-N and denitrification loss in soil were measured. Results showed that imidacloprid and chlorpyrifos had significant boost on the urea hydrolysis. Both imidacloprid and chlorpyrifos had positives effects on soil nitrification at 5 mg/kg treatment. The nitrification rate of the soil increased by 5.63 and 4.33 percent points, respectively, compared with which by urea treatment at the 8th day. When the concentration reached 10 mg/kg, imidacloprid had no effect on soil nitrification, but chlorpyrifos had negative effect; both of the two kinds of pesticides inhibit soil nitrification when the concentration reached 50 mg/kg. Compared with urea treatment, the nitrification rate of the soil decreased by 5.18 and 8.69 percentage points, respectively at the 8th day. The imidacloprid application significantly decreased the nitrogen loss of soil denitrification （P〈0.01）, compared with urea treatment. The 3 concentration treatments reduced denitrification loss of 36.98%, 39.92% and 68.54%, respectively. The chlorpyrifos had no effect on soil denitrification at 5 and 10 mg/kg concentration treatments but showed significant negative effect at 50 mg/kg, reducing denitrification loss of 39.69%.