长期施肥对砂壤质石灰性潮土土壤酸碱缓冲体系的影响

Effects of long-term fertilization on pH buffer system of sandy loam calcareous fluvor-aquic soil

通过长期施肥定位试验,分析了石灰性潮土连续30年施肥处理下土壤pH、碳酸钙和活性碳酸钙含量以及土壤酸碱缓冲容量的变化.结果表明:连续30年施肥处理导致石灰性潮土0～20cm耕层土壤酸化加速,各施肥处理的耕层土壤pH降低0.41～0.70;各施肥处理的耕层土壤酸碱缓冲容量为15.82～21.96cmol·kg-1,单施氮肥明显降低了土壤酸碱缓冲容量,而增施有机肥可显著提高土壤酸碱缓冲容量.土壤酸碱缓冲容量与土壤碳酸钙和活性碳酸钙含量呈显著正相关,与土壤有机质含量和阳离子交换量的相关性不显著,长期不同施肥处理下石灰性潮土仍处于碳酸钙初级缓冲体系,盐基离子和有机质对土壤酸碱缓冲体系的影响较小.0～40cm土层的土壤碳酸钙和活性碳酸钙含量均高于40～80cm土层.与土壤碳酸钙相比,土壤活性碳酸钙更能敏感反映土壤基本理化性状的变化,碳酸钙缓冲体系还可以进一步细分为土壤活性碳酸钙缓冲体系.

Soil samples（0-80 cm） were collected from a 30-year fertilization experimental site in Xuzhou,Jiangsu Province of East China to study the variations of the pH,calcium carbonate and active calcium carbonate contents,and pH buffer capacity of sandy loam calcareous fluvor-aquic soil under different fertilization treatments.Thirty-year continuous application of different fertilizers accelerated the acidification of topsoil（0-20 cm）,with the soil pH decreased by 0.41-0.70.Under different fertilization,the soil pH buffer capacity（pHBC） varied from 15.82 to 21.96 cmol·kg-1.As compared with no fertilization,single N fertilization decreased the pHBC significantly,but N fertilization combined with organic fertilization could significantly increase the pHBC.The soil pHBC had significant positive correlations with soil calcium carbonate and active calcium carbonate contents,but less correlation with soil organic matter content and soil cation exchange capacity,suggesting that after a long-term fertilization,the sandy loam calcareous fluvor-aquic soil was still of an elementary calcium carbonate buffer system,and soil organic matter and cation exchange capacity contributed little to the buffer system.The soil calcium carbonate and active calcium carbonate contents were greater in 0-40 cm than in 40-80 cm soil layer.Comparing with soil calcium carbonate,soil active calcium carbonate was more sensitive to reflect the changes of soil physical and chemical properties,suggesting that the calcium carbonate buffer system could be further classified as soil active calcium carbonate buffer system.