模拟酸雨胁迫与柳杉凋落物对土壤养分及微生物的影响

Soil nutrients and microorganisms with simulated acid rain stress and Cryptomeria fortunei litter

采用不同酸碱度(p H 5.6,p H 4.0,p H 3.0)模拟酸雨、不同质量(400,500,600 g·m-2)柳杉Cryptomeria fortunei凋落物以及模拟酸雨与凋落物复合处理盆栽柳杉幼苗,研究酸雨和凋落物对根际土壤养分含量和微生物数量的影响。结果表明:酸雨胁迫对土壤养分含量和微生物数量具有显著的影响,酸雨处理降低了土壤养分含量和细菌、放线菌数量,增加了真菌数量,影响程度均为p H 3.0>p H 4.0>p H 5.6。随着添加凋落物质量的增加,土壤中氮、磷和钾质量分数以及微生物数量均呈上升趋势,上升程度为600 g·m-2>500 g·m-2>400 g·m-2。不同p H值酸雨与凋落物复合处理中,p H 5.6+500 g·m-2凋落物和p H 4.0+500 g·m-2凋落物处理对土壤氮、磷和全钾质量分数影响均不显著,速效钾质量分数分别比对照增加了43.1%和24.0%(P<0.01);p H 3.0+500 g·m-2凋落物处理土壤全氮、碱解氮、全磷和全钾质量分数等分别比对照下降了14.0%,34.3%,30.0%和23.6%(P<0.01),有效磷质量分数下降了20.3%(P<0.05);p H 5.6+500 g·m-2凋落物处理细菌和放线菌数量分别比对照增加了15.3%和16.7%(P<0.05),p H 3.0+500 g·m-2凋落物处理细菌和放线菌数量分别比对照减少了20.9%和19.4%(P<0.01);p H 4.0+500 g·m-2凋落物和p H 3.0+500 g·m-2凋落物处理真菌数量比对照增加了100.91%和119.18%(P<0.01)。凋落物能够缓解酸雨对土壤养分质量分数和微生物数量的影响。

To clearly show the effects of acid rain stress and litter on soil nutrient content and soil microorgan- ism numbers, rhizosphere soil of Cryptomeriafortunei seedlings was tested with combinations of simulated acid rain （pH 3.0, 4.0, and 5.6） and litter （Lt-400 g＇m-2, Lr500 g.m-2, and L3-600 g＇m-2）. Results showed that soil nutrient content and the quantity of bacteria and actinomyces decreased for the acid rain treatment; whereas, fungi increased with pH 3.0 〉 pH 4.0 〉 pH 5.6. Also, soil N, P, K, and quantity of microorganisms increased as litter increased （L3 〉 L2 〉 L1）. For pH 5.6 ＋ ~ and pH 4.0 ＋ L~ treatments no significant differences in soil N, P, and total K were found, but available K significantly increased （P 〈 0.01 ）. With the pH 3.0 ＋ treatment, total N, available N, total P, and total K significantly decreased （P 〈 0.01） as did available P （P 〈 0.05）. For the pH 5.6 ＋ ~ treatment, soil bacteria and actinomyces significantly increased （P 〈 0.05）. With the pH 3.0 ＋ L2 treatment, soil bacteria and actinomyces significantly decreased （P 〈 0.01）. Also, for pH 4.0 ＋ L2 and pH 3.0 ＋ L2 treatments fungi significantly increased （P 〈 0.01 ）. Thus, litter could alleviate the influence of acid rain on soil nutrient content and microbe quantity. [ Ch, 6 fig. 45 ref. ]