箭筈豌豆种植密度对土壤微生物养分代谢的影响

The effects of Vicia sativa planting density on soil microbial nutrient metabolism

箭筈豌豆是一种优良的绿肥作物,具有固氮、改善土壤结构等功能,在农业生产中使用十分普遍,但目前关于种植箭筈豌豆对土壤微生物养分代谢特征影响的研究还鲜有报道。本研究基于盆栽试验,设置了不同种植密度的箭筈豌豆处理,包括低密度组(19株·盆^(-1))与高密度组(40株·盆^(-1)),同时设置空白土壤作为对照,研究上述处理对土壤养分和微生物特性的影响。结果显示:1)高密度组箭筈豌豆生物量和养分积累量均高于低密度组,从土壤获得的有效养分增加,植物生长受P的限制性增强;2)种植箭筈豌豆高密度组处理显著降低了土壤可溶性无机磷含量,尽管对可溶性有机碳和总氮的影响不显著,但可溶性总氮较对照明显有降低的趋势,最终对土壤可溶性养分计量比RC:N、RC:P、RN:P的影响不显著;3)种植箭筈豌豆增加了SMBC、SMBN含量和SMBC∶SMBP、SMBN∶SMBP,降低了SMBP含量和SMBC∶SMBN,表明微生物生长对N的需求量增加;4)种植箭筈豌豆降低了土壤BG(C-获取酶)酶活性而增加了(NAG+LAP)(N-获取酶)和AP(P-获取酶)酶活性,降低了BG∶(NAG+LAP)、BG∶AP和(NAG+LAP)∶AP,表明土壤微生物通过增加N和P获取的酶活性以增加对短缺养分的获取。因此,种植不同密度的箭筈豌豆在改变土壤养分特征的同时,还改变了土壤微生物养分代谢特征,微生物通过调整体内养分含量及胞外酶的分泌量及计量比以适应新的资源供应特征。

Vicia sativa is an excellent green manure crop which provides nitrogen fixation and soil structure improvement.It is very common in agricultural production.However,there is still little published research on the effects of planting V.sativa on the characteristics of soil microbial nutrient metabolism.This research is based on a pot experiment and set up V.sativa treatments with a range of planting densities,including a low-density group(19 plants·pot^(-1)),a high-density group(40 plants·pot^(-1)),and bare soil as a control,to study the effects of the above treatments on the soil.It was found that:1)The biomass and nutrient accumulation of V.sativa in the high-density group were greater than in the low-density group.Thus,nutrients extracted from the soil were increased at high planting density,and plant growth was restricted by P.2)In the high-density planting of V.sativa,the content of soluble soil inorganic phosphorus was significantly reduced.While the density treatments did not differ significantly for soluble organic carbon and soluble total nitrogen,the values for soluble total nitrogen with V.sativa planting were significantly lower than for the control.As a result,the soil soluble nutrient ratios RC:N,RC:P,RN:P were altered,though not significantly so.3)Planting of V.sativa increased the contents of soil microbial biomass C,soil microbial biomass N,soil microbial biomass C∶P,and soil microbial biomass N∶P,and decreased the contents of soil microbial biomass P and soil microbial biomass C∶N,indicating that the demand for N for microbial growth increased.4)Planting V.sativa increased[β-N-acetylglucosaminidase(NAG)+leucyl aminopeptidase(LAP)]and alkaline phosphatase(AP)enzyme activities,and decreasedβ-1,4-glucosidase(BG)enzyme activity,BG∶(NAG+LAP),BG∶AP and(NAG+LAP)∶AP,indicating that the soil microbes increased the activities of(NAG+LAP)and AP enzymes to increase access to nutrients in short supply.Therefore,different planting densities of V.sativa not only changed the soil nutrient content,but also changed the characteristics of soil microbial nutrient metabolism.The microbes adjusted their internal nutrient contents and the secretion rates and ratios of extracellular enzymes to adapt to the prevailing resource supply characteristics.