赤子爱胜蚓对赤红壤铝形态的影响

【目的】研究蚯蚓添加对华南地区赤红壤酸化特征和铝(Al)形态的影响,为华南赤红壤的酸化改良提供理论依据。【方法】通过室内盆栽试验,用赤红壤培养赤子爱胜蚓Eisenia fetida 40 d后测定蚓粪和土壤pH、有机质、全氮和阳离子交换量(CEC);通过连续浸提法测定土壤各铝形态含量,包括交换态铝(Al_(Ex))、弱有机结合态铝(Al_(Orw))、有机结合态铝(Al_(Or))、无定形态铝(Al_(Amo))、氧化铁结合态铝(Al_(Oxi))、非晶态铝硅酸盐和三水铝石(Al_(Aag));采用主成分分析法研究不同处理土壤中铝的形态分布。试验以未添加蚯蚓的土壤为对照。【结果】与对照相比,蚓粪的pH提高了1.27,全氮、CEC、Al_(Or)以及交换性K、Na、Ca含量分别提高了62.16%、38.22%、355.70%、151.38%、65.38%和51.90%;蚓粪和土壤Al_(Ex)含量分别降低了50.95%和53.14%。蚓粪的pH、CEC、Al_(Or)含量和交换性K、Na、Ca含量显著高于未吞食土壤。【结论】蚯蚓可提升土壤pH和土壤Al_(Or)的含量,促进交换性Ca、Mg的释放,降低土壤Al Ex含量。

Influence of Eisenia fetida on aluminum fractions in latosolic red soil

Objective To investigate the impacts of earthworms on soil acidification characteristics and aluminum (Al) fractions of latosolic red soil in South China, and provide a theoretical basis for acidification improvement of latosolic red soil in South China.Method The earthworms (Eisenia fetida) were incubated with latosolic red soil under laboratory conditions. After 40 days of incubation, Al fractions in earthworm cast and soil,namely exchangeable (Al_Ex), weakly organically bound (Al_Orw), organically bound (Al_Or), amorphous (Al_Amo), Al occluded in crystalline iron oxides (Al_Oxi), and amorphous aluminosilicate and gibbsite (Al_Aag) fractions, were determined using sequential extraction methods. Earthworm cast and soil pH, organic carbon, total nitrogen, and cation exchange capacity (CEC) were determined. The principal component analyses were applied to study the distribution of different Al fractions in different treated soils. And the soil without earthworm was set as a control.Result Compared to the control soil, pH of earthworm casts increased by 1.27, the total nitrogen, CEC, Al_Or and exchangeable K, Na, and Ca contents increased by 62.16%, 38.22%, 355.70%, 151.38%, 65.38% and 51.90%, respectively, and Al_Ex contents in earthworm casts and soil decreased by 50.95% and 53.14% respectively. The pH, CEC, Al_Or and exchangeable K, Na, Ca contents in casts were significantly higher than those in non-ingested soil.Conclusion Earthworms can significantly increase soil pH and Al_Or, promote the release of exchangeable Ca²⁺ and Mg²⁺, and reduce soil Al_Ex content.