余江县水稻土剖面酸缓冲性能与酸化速率

为探明不同母质发育的水稻土在剖面层次上的缓冲性能特征及酸化速率大小，以红砂岩和河流冲积物母质发育的水稻土为对象，测定不同层次（0~20、20~40、40~60、60~80 cm和80~100 cm）土壤的pH、有机质、全氮、阳离子交换量和酸碱缓冲容量，定量比较不同母质和不同土层酸碱缓冲容量的变化及差异。结果表明：以红砂岩和河流冲积物母质发育的水稻土酸碱缓冲容量在0~20 cm土层比80~100 cm土层分别显著升高10.14 mmol·kg^-1和4.18 mmol·kg^-1，且随着水稻土初始pH（不加酸碱的pH）的增加，其酸碱缓冲容量也呈增加趋势。在0~20 cm土层，红砂岩母质发育的水稻土酸碱缓冲容量比河流冲积物母质显著增加7.38mmol·kg^-1；在20~100 cm土层，2种母质发育的水稻土酸碱缓冲容量无显著差异。红砂岩母质发育水稻土表层酸化速率（0.78kmol H⁺·hm^-2·a^-1）大于河流冲积物母质（0.36 kmol H⁺·hm^-2·a^-1）。水稻土酸碱缓冲容量与pH呈极显著负相关（P<0.01），与交换性盐基总量呈显著负相关（P<0.05），与阳离子交换量、有机质、全氮和交换性酸呈极显著正相关（P<0.01）；水稻土pH与有机质、全氮和交换性酸呈极显著负相关，与交换性盐基总量呈极显著正相关（P<0.01），与阳离子交换量无相关性。研究表明，酸碱缓冲曲线可以很好地反映不同母质发育的水稻土在不同土层上对加酸、加碱量的敏感程度；随着土层深度的增加，2种母质的酸碱缓冲容量呈下降趋势，其中在0~20 cm土层，红砂岩母质发育的水稻土酸碱缓冲容量和酸化速率最高，其酸碱缓冲容量主要与初始pH、有机质、全氮、阳离子交换量、交换性盐基总量和交换性酸有关，且2种母质发育水稻土均处于铝硅酸盐矿物分解和交换性盐基离子缓冲阶段。

Research on buffering capacity and acidification rate of paddy soil profiles in Yujiang County

To explore paddy soil acid buffering capacity and acidification rate characteristics,the study analyzed paddy soil pH, organic matter, total nitrogen, cation exchange capacity and acid buffering capacity of different depths (0~20, 20~40, 40~60, 60~80 cm and 80~100 cm) derived from red sandstone and river alluvial parent material, quantitatively compared the changes and differences of acid buffer capacity in different soil parent materials and depths. The results showed that paddy soil acid buffering capacity increased by 4.18~10.14 mmol·kg^-1 at the 0~20 cm than 80~100 cm soil layer, and it increased with the increasing of initial pH (pH without acid or alkali addition). At the 0~20 cm, paddy soil acid buffering capacity derived from red sandstone parent material significantly increased by 7.38 mmol·kg^-1 than that from river alluvium. At 20~100 cm, there were no significant difference between acid buffering capacity of paddy soil derived from two parent materials. Paddy soil acidification rate (0.78 kmol H⁺·hm^-2·a^-1) at topsoil derived from red sandstone was greater than that from river alluvium (0.36 kmol H⁺·hm^-2·a^-1). Paddy soil acid buffering capacity derived from two parent materials was significantly negatively correlated with pH, total exchangeable base (P<0.05), positively correlated with cation exchange capacity, organic matter, total nitrogen and exchangeable acid (P<0.01); Paddy soil pH was significantly negatively correlated with organic matter, total nitrogen and exchangeable acid, positively correlated with total exchangeable base (P<0.01), and not correlated with the cation exchange capacity (P>0.05). The results showed, the acid buffer curve could reflect the sensitivity of paddy soil derived from different parent materials on the amount of acid and alkali addition in different soil layers; With the increase of soil depth, paddy soil acid buffering capacities derived from two parent materials were on the decline, and at 0~20 cm, paddy soil acid buffering capacity and acidification rate derived from red sandstone parent material was highest, and its acid buffering capacity was mainly related to initial pH, organic matter, total nitrogen, cation exchange capacity, total exchangeable base and exchangeable acid; Paddy soil derived from two parent materials were mainly in the buffering phase of aluminosilicate mineral decomposition and exchange base ion.