红壤小流域不同土地利用方式对土壤微生物量碳氮的影响

Effects of Different Land Used Patterns on Soil Microbial Biomass Carbon and Nitrogen in Small Red Soil Watershed

以我国南方红壤丘陵区为背景,研究了红壤小流域花生地、花-橘间作、橘园和板栗园4种不同土地利用方式对土壤微生物量的影响。结果表明,土地利用方式对土壤微生物量有显著影响,其中0￣5cm土层土壤微生物量碳依次为板栗园>橘园>花-橘间作>花生地,而土壤微生物量氮则为板栗园>花生地>花-橘间作地>橘园。4种土地利用方式下土壤微生物量碳、氮均呈现出高度的坡位变异,坡麓土壤微生物量碳、氮明显高于坡顶和坡中,且这种分异主要反映在0￣5cm土层,其中从坡顶到坡麓0￣5cm土层土壤微生物量碳增幅依次为板栗园(28%)>花生地(24%)>橘园(13%)>花-橘间作地(7%);而土壤微生物量氮为花生地(29%)>橘园(14%)>板栗园(13%)>花-橘间作地(8%)。相关分析表明,土壤微生物量碳、氮与土壤容重、含水量、有机碳呈显著相关,而与土壤全磷、有效磷相关性不明显。

Soil microbial biomass has been identified as an appropriate index to denote the soil quality by many researchers because of its good indicative function. This study was carried out at the Ecological Experiment Station of Red Soil in Yujiang County, Jiangxi Province of China, a typical suhtropical monsoon region characterized by a warm wet spring and a hot-dry summer, the landscape of low hill with slope gradient from 5° to 8°. The effect of different land used patterns on the soil microbial biomass was studied by investigating the contents of soil microbial biomass carbon （SMBC） and soil microbial biomass nitrogen （SMBN） in four land used patterns, including Chinese chestnut land, mandarin orange land, peanut-orange land and peanut land; The results showed that the contents of SMBC and SMBN under four land used patterns were obviously different, and the contents of SMBC in 0-5 cm soil layer in four land used patterns showed： Chinese chestnut land〉 mandarin orange land〉peanut-orange land〉peanut land; while the order of SMBN were： Chinese chestnut land〉peanut-orange land〉peanut land〉mandarin orange land. The Slope site difference of the contents of SMBC and SMBN in each land also was obvious, with the increasing trend from upper site to under site, which especially represented in 0-5cm soil layer. The increasing rates of the contents of SMC from upper site to under site in 0-5 cm differed under four land used patterns： Chinese chestnut land（28%）〉peanut land（24%）〉 mandarin orange land （13%）〉peanut-orange land（7%）, and the increase of SMN showed： peanut land（29%）〉mandarin orange land（14%）〉Chinese chestnut land （13%）~peanut-orange land （8%）. The contents of SMBC and SMBN showed significantly positive correlations with soil organic, moisture, bulk density, but little relationships with soil total P and available P.