翻压接种根瘤菌的紫花苕子对植烟土壤肥力的影响

为探究翻压接种根瘤菌的紫花苕子对植烟土壤酶活性及微生物数量等的影响,在烤烟地冬闲时种植接种根瘤菌的紫花苕子(VR)与不接种根瘤菌的紫花苕子(V),并预留不种苕子的冬闲地(CK)。紫花苕子初花期时(生育期187 d)采集植株测定其生物学性状及养分含量,然后全部翻压回田,45 d后种植烤烟。烤烟种植时,冬闲地按照广元烟草公司推荐施肥量,即全量施肥(CF);不接种根瘤菌的紫花苕子翻压并减少20%施肥量(V-20%CF);接种根瘤菌的紫花苕子翻压并减少20%施肥量(VR-20%CF)。烤烟种植前及收获后,采集土壤测定理化性状、酶活性及微生物数量。结果表明:1) 接种根瘤菌能增加紫花苕子的生物量及养分含量,相比不接种根瘤菌的紫花苕子,鲜草产量、干草产量、根产量、总瘤数、株高增加1.3%~50.7%;全氮、全磷、全钾含量增加1.8%~5.0%;氮磷钾积累量增加14.3%~21.5%。2) 测定种烟前土壤可知,翻压接种根瘤菌的紫花苕子能更有效地增加土壤养分含量及微生物数量,与冬闲地比较,全氮、有机质、碱解氮、有效磷、速效钾增加2.5%~126.6%;蔗糖酶、过氧化氢酶、磷酸酶、脲酶活性增加14.6%~82.5%;细菌、放线菌、真菌增加85.3%~236.9%。测定收烟后土壤可知,减少20%施肥量的情况下,翻压接种根瘤菌的紫花苕子能够增加土壤养分含量及微生物数量,与全量施肥比较,全氮、有机质、碱解氮、有效磷、速效钾增加12.3%~64.1%;蔗糖酶、过氧化氢酶、磷酸酶、脲酶活性增加5.4%~67.0%;细菌、放线菌、真菌数量增加65.1%~473.3%。在减少20%施肥量的情况下,翻压接种根瘤菌的紫花苕子能够更有效地培肥地力,改善土壤环境,对实现烟叶生产可持续发展具有重要的意义。

Effects of a Vicia villosa green-manure crop inoculated rhizobium during winter fallow,on soil fertility factors and fertilizer needs of a summer tobacco crop

In order to investigate the effect on crop yield and soil fertility of Vicia villosa as a green manure crop in tobacco growing, a field experiment comprising three treatments was set up: winter fallow without a green manure crop (CK), a winter green manure crop of V. villosa not inoculated with rhizobium (V), and a winter green manure crop of rhizobium-inoculated V. villosa (VR). Plants of V. villosa were harvested for measurement at the beginning of flowering (187 days after planting) to determine their yield and nutrient levels, and then ploughed under, with tobacco planting following 45 days later. For tobacco planting on V and VR plots, fertilizer was applied at 80% of the rates recommended by the Guangyuan Tobacco Company for the CK treatment. Before planting tobacco and after harvest, soil samples were collected and physicochemical traits, enzyme activity and microbial populations were determined. Key results were: 1) Rhizobium inoculation enhanced vigor of the V. villosa green manure crop. Plant biomass and nutrient content, fresh grass yield, hay yield, root yield, nodule numbers, and plant height were all increased by 1.3% to 50.7%; total N, total P, and total K were increased by 1.8% to 5.0%; N, P, and K accumulation increased by 14.3% to 21.5%. 2) In the soil tests taken before planting tobacco, the VR treatment had increased soil nutrient content and microbial populations, compared with the CK treatment. Specifically, total N, organic matter, and available N, P, and K increased by 2.5% to 126.6%. Meanwhile, the activities of sucrase, catalase, phosphatase and urease were increased by 14.6% to 82.5%, while populations of bacteria, actinomycetes and fungi were increased by 85.3% to 236.9%. In the soil tests taken after harvesting tobacco, it was found that the VR treatment increased soil nutrient content and microbial populations, even with the 20% reduction in chemical fertilizer application. Total N, organic matter, and available N, P, and K were increased by 12.3% to 64.1%, the activities of sucrose, catalase, phosphatase and urease increased by 5.4% to 67.0%, compared to CK, while populations of bacteria, actinomycetes and fungi were increased by 65.1% to 473.3%. This finding that use of rhizobium-inoculatedd V. villosa (i.e. the VR treatment) can improve soil fertility status even with a 20% reduction in inorganic fertilise application, is of great significance to development of more sustainable tobacco leaf production practices.