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.