Abstract:

The critical pH was the target pH for soil acidity improvement， which has important guiding significance for agricultural production and sustainable development. A pot experiment was conducted to investigate the effect of soil initial properties affecting the response of wheat growth to pH. 5 soils derived from plate shale， quaternary red earth， river alluvium， tertiary red sandstone， and granite were used in this study. The results showed that the maximum shoot biomasses of wheat were 2.71， 1.17， 2.06， 1.57 and 1.70 g·pot^-1 for soils derived from plate shale， quaternary red earth， river alluvium， granite， and tertiary red sandstone， respectively. The critical values of pH_95%， pH_50%， or pH_5% were defined as shoot biomass reaching to 95%， 50%， or 5% of maximum values. The pH_95%， pH_50%， or pH_5% were 5.31， 4.42， and 3.53 for soil derived from plate shale， 5.79， 4.79， and 3.80 for quaternary red earth， 5.25， 4.71， and 4.16 for river alluvium， 4.94， 4.61， and 4.29 for tertiary red sandstone granite， and 5.72， 4.66， and 3.59 for granite， respectively. The maximum values of shoot biomass had significant positive correlations with soil initial pH， available P， exchangeable Mg and exchangeable Ca. The pH_50% of wheat shoot biomass was negatively correlated with soil initial available P； and the pH _50% of wheat height was negatively correlated with soil initial available P and exchangeable Mg. The data indicated that soil initial available P and exchangeable Mg shaped the response of wheat growth to pH and the maximum values of crop biomass were determined by both soil nutrient status and acidity. Therefore， we recommend that co-amelioration of soil fertility and acidity was a practical method to reach a best condition for plant growth.

Key words: soil parent materials, critical values, available P, exchangeable Mg, pH

摘要：

酸害阈值作为土壤酸度改良的目标pH，对农业生产和可持续发展具有重要指导意义。通过盆栽试验，分析了5种不同母质土壤上小麦生长对pH的响应及其与土壤初始性质的关系。结果表明，板页岩、第四纪红土、河流冲积物、红砂岩和花岗岩发育的红壤上小麦地上部生物量稳定值分别为2.71、1.17、2.06、1.57和1.70 g·pot^-1；达到稳定值95%、50%和5%时的pH阈值（即pH_95%、pH_50%、pH _5%），板页岩发育的红壤分别为5.31、4.42和3.53，第四纪红土发育的红壤分别为5.79、4.79和3.80，河流冲积物发育的红壤分别为5.25、4.71和4.16，红砂岩发育的红壤分别为4.94、4.61和4.29，花岗岩发育的红壤分别为5.72、4.66和3.59。小麦地上部生物量稳定值与土壤初始pH、有效磷、交换性镁和交换性钙含量呈显著或极显著正相关，pH_50%与有效磷含量呈显著负相关；株高pH_50%与土壤初始有效磷含量、交换性镁含量呈显著负相关。结果表明作物酸害阈值受土壤初始有效磷和交换性镁含量的影响，土壤肥力水平和酸度共同决定了作物的最大生物量，为培肥土壤、降低酸害影响提供了科学依据。

关键词: 不同母质土壤, 酸害阈值, 有效磷, 交换性镁, pH