绿肥在湘西烟田中的腐解和养分释放动态

为明确绿肥在植烟土壤中的腐解和养分释放规律,采用尼龙网袋法研究了光叶紫花苕子(Vicia villosa Roth var.)、箭舌豌豆(Vicia sativa L.)、紫云英(Astragalus sinicus L.)、黑麦草(Lolium perenne)在湘西烟田中的腐解动态。结果表明:绿肥中有机物腐解和养分释放量在翻压前两周分解速率最快,第3~7周分解速率中等,7周以后较慢。绿肥翻压前两周有机物平均每周的腐解率为12.50%~19.18%,碳、氮、磷、钾平均每周的释放率分别为13.05%~19.56%,20.08%~26.59%,17.86%~26.08%和16.97%~26.08%;第3~7周有机物平均每周的腐解率为6.16%~8.58%,碳、氮、磷、钾平均每周的释放率分别为6.23%~8.62%,5.71%~7.83%,4.47%~5.29%和7.01%~8.49%;7周以后有机物平均每周的腐解率为0.65%~0.96%,碳、氮、磷、钾平均每周的释放率分别为0.65%~1.48%,0.50%~1.09%,0.65%~1.36%和0.51%~1.14%。绿肥翻压后49 d时,有机物的累计腐解率为60.64%~70.57%,碳、氮、磷、钾累计释放率分别为62.17%~71.32%,75.68%~83.03%,70.61%~84.78%和73.88%~80.12%。绿肥养分在翻压后7周内以氮的释放量最大,黑麦草在翻压后两周内有机物腐解和养分释放慢于其他绿肥;箭舌豌豆在翻压后第3~7周内有机物腐解和养分释放慢于其他绿肥。绿肥翻压后的碳氮比(C/N)呈上升趋势,C/N达到24的最早时间为翻压后第7周。 

Dynamics of Decomposition and Nutrient Release of Green Manures in Tobacco Fields in Xiangxi

In order to explore the rules of nutrient release and organic decomposition of green manures in soil,the decomposition dynamics of smooth vetch(Vicia villosa Roth var.),common vetch(Vicia sativa L.),milk vetch(Astragalus sinicus L.),perennial ryegrass(Lolium perenne) in tobacco fields were studied via burying these green manures packed in nylon string bags into the plow layer of tobacco fields.The results showed that the organic matter in green manures decomposed rapidly in the first 2 weeks after burying,and moderately from the third to seventh weeks,slowly after seven weeks.In the first 2 weeks,the average decomposition rate of organic matters was 12.50%-19.18% per week and the average release rates of C,N,P,K were 13.05%-19.56%,20.08%-26.59%,17.86%-26.08%,16.97%-26.08% per week,respectively;from the third to seventh weeks,which were 6.16%-8.58% and 6.23%-8.62%,5.71%-7.83%,4.47%-5.29%,7.01%-8.49%,respectively;after seven weeks,which were 0.65%-0.96% and 0.65%-1.48%,0.50%-1.09%,0.65%-1.36%,0.51%-1.14%,respectively.In seven weeks,the total decomposition rate of organic matters was 60.64%-70.57%,the total release rates of C,N,P,K were 62.17%-71.32%,75.68%-83.03%,70.61%-84.78%,73.88%-80.12%,respectively,and the amount of N release were the highest.Comparatively,the rates of nutrient release and organic matter decomposition were slower for perennial ryegrass in the first 2 weeks;for common vetch were slower from the third to seventh weeks.The C/N ratio increased after green manure burying,it did not reach 24 until the seventh week after burying.