耕地棕壤酸碱缓冲性能及酸化速率研究

辽宁省耕地棕壤自第二次土壤普查以来酸化趋势明显,pH整体平均值从第二次普查时期的6.42降至5.73。对辽宁省4个典型地区(昌图、沈阳、瓦房店、清原)的耕地棕壤耕层(0-20cm)缓冲性能、酸化速率及其影响因素进行研究,结果表明:各地区酸碱缓冲容量变幅为29.66～39.87mmol/kg.pH unit,其中辽宁北部和中部地区酸碱缓冲容量明显高于辽南和辽东地区。酸化速率以辽南地区下降速率最快,其值为2.69H+kmol/(hm2.a),而速率最慢的地区为辽东,其酸化速率为1.44H+kmol/(hm2.a)。土壤初始pH、阳离子交换量、颗粒组成及有机质含量均是影响酸碱缓冲容量变化的主要因素。北部和中部质地以粉(砂)壤土为主,阳离子交换量、盐基饱和度及粘粒含量均高于南部和东部地区,因此缓冲性能也较强。施肥及其他人为因素对辽宁耕地棕壤酸碱缓冲容量及酸化速率的影响有待进一步研究。

Research on pH Buffer Capacity and Acidification Rate of Arable Brown Soil

Significant acidification has taken place in the arable brown soil of Liaoning province since the second soil general survey.The general mean of pH were declined from 6.42 to 5.73.Arable brown soil(0-20 cm) of the four typical areas in Liaoning province(Changtu,Shenyang,Wafangdian and Qingyuan) were used to study the pH buffer capacity,acidification rate and the influencing factors.The results showed that pH buffer capacity in the four areas were from 29.66 to 39.87 mmol/kg·pH unit.The pH buffer capacity of the north and middle area in Liaoning province were higher than the south and east area.The acidification of south area was the fastest with the value of 2.69 H+ kmol/(hm2·a),and the slowest happened in the east with the value of 1.44 H+ kmol/(hm2·a).The initial pH,cation exchange capacity,soil mechanical composition and organic matter were all the factors that affect the changes of soil pH buffer capacity.The texture in the north and middle area were silt loam soil,cation exchange capacity,base saturation and clay content were higher than that in the other two areas(south and east).Therefore,they had the higher pH buffer capacities.Fertilization and the other human factors that contribute to buffer capacity and acidification rate need to be further studied.