Acid-base Buffering Ability Of Long-term Fertilization Soil & Red Soil Improvement With Quicklime

Due to human activities, modern farming system and agricultural management measures and industrialization,the problem of soil acidification has become more and more prominent. The uses of large quantities of chemical fertilizer has resulted in the acceleration of oil acidification, the loss of soil nutrient, the increase of aluminum and heavy metals activity and the decrease of microbial activity, the deterioration of soil physical and chemical properties, and the decline of crop production. The tendency has endangered the agro-ecological system. Soil buffer capacity of reflects the sensitivity of soil to acid and alkali. The acidification trends can be predicted by the study of soil buffer capacity. The application of lime on the acid red soil, not only can increase the pH in the acid soil, but also provide mineral elements to soil, which is useful to maintain and improve soil fertility in red soil.In this paper, soil buffering ability was studied by using Qiyang red soil CK, NPK, Jiangxi Red Soil N, NPK, NPKM, Zhengzhou damp soil NPK and Harbin Black soil CK, N. The results showed that the buffering capacity varied in different soil, with the values of 15.353; 17.162; 18.384; 16.935; 26.864; 49.393; 15.855; 17.006 (m mol / kg), respectively. The order of buffer capacity in Qiyang red soil treatment was CK> NPK and NPKM> NPK> N for Jiangxi Red soil, CK> N for Harbin Black soil. The discussion of possible buffering process of soil to acid and base indicated that the process included three main stages although each stage may vary in different soils.The effect factor of soil buffer capacity was also discussed. Buffering ability of soil to acid was related to the physical chemical properties of soil, such as CEC, organic matter and clay mineral content. The acid buffer capacity of Jiangxi Red Soil was increased as the organic matter content increased, and soil organic matter content was positively correlated with buffer capacity. Qiyang Red soil and Jiangxi Red Soil CEC was positively related to acid buffering capacity. The correlation coefficient for the three treatment of Jiangxi red soil was 0.993639 and 0.779753 for the five treatments in Qiyang red soil and Jiangxi red soil. The buffer capacity of Harbin black soil and Qiyang red soil was positively related to clay content. For Jiangxi Red Soil, the buffering capacity of N, NPK treatment was positively correlated with clay content except for NPKM treatment. There was no obvious correlation between acid buffering capacity and its initial soil pH value in all treatments studied.The gradient amount of quicklime was set based on red soil buffering curves. Pot experiment was carried out after the balance of soil with quicklime added. The results showed that cabbage biomass increased with the increase of quicklime applied. Soil pH also increased after soil balance. The content of available soil N and available K rose with the increase of the amount of lime, while the variation of available P content was not obvious. For long-term fertilization soil, the theoretical pH value based on buffering curve and the actual pH value matched well after the addition of lime if the amount used was within the limited range. The result indicated that the method using buffering curve to estimate the amount of lime to be used was only suitable to some situation.