干旱区盐碱地不同栽培草地土壤理化性质及微生物数量

对宁夏干旱区盐碱地6种栽培草地0-20、20-40 cm土层土壤理化性质、土壤养分含量及微生物数量进行比较,旨在筛选出改善干旱区盐碱地土壤品质的优良草地。结果表明,各栽培草地0-20 cm土壤含水量、容重、pH值均低于20-40 cm,土壤养分及全盐含量均高于20-40 cm;豆科栽培草地改善两层土壤有机质、全氮、速效氮及降低20-40 cm全盐的效果强于禾本科,禾本科栽培草地保水蓄水、降低土壤容重及增加20-40 cm土层速效磷的效果强于豆科;豆科、禾本科栽培草地改善土壤品质的效果大小分别为紫花苜蓿(Medicago sativa)＞沙打旺(Astragalus adsurgens)＞黄花草木樨(Melilotus offcinalia)和圆柱披碱草(Elymus cylindricus)＞扁穗冰草(Agropyron cristatum)＞蒙杂冰草(A.cristatum×A.mongolicum);各栽培草地0-20 cm土层细菌、放线菌及真菌数量远大于20-40 cm土层,豆科、禾本科栽培草地两层土壤中3种微生物数量大小分别为紫花苜蓿＞沙打旺＞黄花草木樨和圆柱披碱草＞扁穗冰草＞蒙杂冰草;0-20 cm土壤含水量与真菌数量呈显著正相关(P0.05),20-40 cm土壤pH值与放线菌、真菌数量呈显著负相关(P0.05);两层土壤的全盐含量与细菌、放线菌及真菌数量均呈负相关,有机质、全氮、速效氮和速效钾与细菌、放线菌数量均呈极显著正相关(P0.01),速效磷、速效钾与真菌数量呈极显著正相关(P0.01)。

Soil physico-chemical properties and microbial quantities in different pastures in arid area of saline-alkali soil

Soil of 0-20 cm and 20-40 cm soil layer were sampled from 6 different cultivated grassland in arid and saline-alkali area of Ningxia to analysis their physico-chemical properties, nutrient content and soil microbial quantity and screen the best grassland to improve soil quality. The results showed that soil moisture content, bulk density, pH in 0-20 cm layer were lower than that in 20-40 cm layer in the cultivated grassland. Soil nutrient and soil total salt content in 0-20 cm layer were higher than that in 20-40 cm. Leguminous pasture grassland performed better in increasing soil organic matter, total nitrogen, available nitrogen in both sampled layers and reducing soil salinity in 20-40 cm compared with other gramineae pastures. Gramineous pastures performed better in improving water conservation, reducing soil bulk density and increasing soil available phosphorus in 20-40 cm soil compared with other leguminous pastures. The ability of legume to improve the soil quality decreased in the following order: Medicago sativa＞Astragalus adsurgens＞Melilotus offcinalia. The ability of gramineae to improve soil quality decreased in the following order: Elymus cylindricus＞Agropyron cristatum＞A.cristatum×A.mongolicum. For all of the studied cultivated grassland, there were more soil bacteria, actinomycetes, fungi in 0-20 than in 20-40 cm. The numbers of these 3 tested microorganism also varied with cultivated pasture. For leguminosae, the number of microorganism decreased in the following order: M.sativa＞A.adsurgens＞M.offcinalia. For gramineae, the number of microorganism decreased in the following order E.cylindricus＞A.cristatum＞A.cristatum×A.mongolicum. Soil water content in 0-20 cm was significantly positive correlated with numbers of fungi (P0.05). Soil pH value and the number of actinomycetes and fungi in 20-40 cm were significant negative correlated (P0.05). Soil total salt contents in both layers were negatively correlated with the numbers of bacteria, actinomyces and fungi. Organic matter, total nitrogen, available nitrogen, phosphorus and potassium were significant positive correlated (P0.01) with the numbers of bacteria, actinomyces. Available phosphorus and available potassium were significantly positively correlated with the number of fungi (P0.01).