除草剂对不同种植年限柑橘园土壤氮转化过程及温室气体排放的影响

Soil microbes have significant influences on transformation and fate of nitrogen in soils by participating in the processes of biology and biochemistry in soil nitrogen cycle. Research has shown that herbicides may inhibit non-target soil microbes and their biochemical processes. Therefore, herbicides produced great effectives on the uptake and utilization by plant and environmental release of nitrogen from soils. This experiment aimed to explore the effects of herbicide on transformation of urea nitrogen and greenhouse gas emissions in different planting years orchard soil, it is helpful to evaluate the environmental safety of herbicide and nitrogen application in orchard soil. An twofactorsthreelevelsCompleteexperiment (Herbicide factors include no herbicides, glyphosate (10 mgkg-1 a.i.)and butachlor(10 mgkg-1 a.i.), planting year factors include 0 years (woodland), 10 years and 30years citrus orchard ) was conducted under laboratory condition, and 200 mg(N)kg-1 dry soil urea were applied in each treatments respectively. The result showed that the Urea hydrolysis rate, nitrification rates, denitrification loss and green house gas emission of citrus orchard (10 and 30 years) were higher than the woodland (P < 0.05). Compare with woodland soil, the total denitrification loss increased by 5.12 and 4.30 times; the total N2O emission increased by 7.80 and 2.74 times; the total CO2 emission increased by 19.62% and 39.64%, respectively. The Urea hydrolysis rate, nitrification rates and CO2 emission in 30 years citrus orchard were significantly greater than the 10 years. Compare with 10 years citrus orchard soil, the total CO2 emission in 30 years increased by 16.74%, but the total denitrification loss were no difference between 2 citrus orchard soils. Glyphosate and butachlor had significant boost the urea hydrolysis in woodland, but had no effect on soil nitrification in 3 soils. The butachlor had significant negative effect on woodland CO2 emission, but show no effect on citrus orchard soil. Compare with no herbicide treatment, the butachlor had significant boost the N2O emission 56.27% and 85.41% respectively (P < 0.05), in 2 citrus orchard soil. The glyphosate no effect on soil total CO2 and N2O emission in 3 soil. The glyphosate had no significant effects on nitrogen transformation and greenhouse gas emission in citrus orchard soil, but butachlor had significant boost the N2O emission in citrus orchard soil.