不同氮肥用量下乙草胺对土壤氮转化过程的影响
Effects of acetochlor on transformation of urea nitrogen in soil at different nitrogen fertilizer application rates

在实验室培养条件下,研究了不同氮肥用量水平下土壤中分别添加除草剂乙草胺对尿素态氮的水解、硝化及反硝化等氮素转化过程的影响。试验设7个处理,分别为施氮量0、75、150和300mg/kg以及氮75、150、300mg/kg+乙草胺(有效成分10mg/kg)处理。结果表明:当施氮量为75mg/kg时,乙草胺对尿素态氮的水解和硝化作用明显影响;施氮量为150和300mg/kg时,乙草胺可抑制尿素态氮的水解过程(P<0.05),24h时其尿素态氮的水解率分别比不施乙草胺的处理降低了10.1%和9.8%,48h时乙草胺对尿素态氮的水解过程基本影响。当施氮量为75和150mg/kg时,整个培养期间其氮素的反硝化作用和空白对照差异,施用乙草胺对其反硝化作用的影响也不显著;施氮量为300mg/kg时则土壤中氮素的反硝化作用显著增强,其反硝化损失总量为13221μg/kg,是空白处理的117倍,而在此氮量水平下施用乙草胺具有显著抑制氮素反硝化损失的效应,其反硝化损失总量为10814μg/kg,比不施乙草胺的处理降低了18.2%(P<0.01)。研究表明,施用乙草胺对土壤中氮素的转化过程具有一定影响,然而在不同的施氮量条件下,其影响效果差异较大,高氮时影响更明显。
In order to assess the effects of acetochlor on transformation of urea nitrogen in soil at different nitrogen fertilizer application rates. An incubation experiment was conducted under laboratory conditions with 7 treatments including nitrogen (0, 75, 150 and 300 mg/kg), nitrogen (75, 150 and 300 mg/kg) plus acetochlor (10 mg/kg, active ingredient). The results showed that, acetochlor had no significantly effect on soil urea hydrolysis and nitrification at 75 mg/kg nitrogen concentration treatments. However, significant negative effect on soil urea hydrolysis was observed at 150 and 300 mg/kg nitrogen concentration treatments (P < 0.05). And, during a period of 24 h, the soil urea hydrolysis rate was decrease by 10.1% and 9.8% respectively. The urea fertilizer has no significant effect on the denitrification loss at 75 and 150 mg/kg concentration treatments. When the nitrogen concentration increased to 300 mg/kg, the total amount of denitrification loss increased to 13 221 μg/kg which was 117 times higher than the control treatment. The acetochlor has no significant effect on denitrification loss at 75 and 150 mg/kg nitrogen concentration treatments. However, significant negative effect was observed at the concentration of 300 mg/kg, which reduced the denitrification loss by 18.2% (P < 0.01). This study demonstrated that acetochlor markedly affected the nitrogen transformation in soil. However, under different nitrogen fertilizer application rates, different impacts on the processes of nitrogen transformation were detected.