不同磷水平对红壤溶液中锰、铝、镁和钙浓度变化以及小麦生长的影响

为了探明不同磷水平对红壤中土壤溶液主要金属离子变化的影响以及小麦对磷的响应,确定红壤中小麦适宜的施磷水平,采用原位提取土壤溶液和比较生物量的方法,监测了短期内红壤溶液中主要金属离子浓度变化及小麦生物量的变化。结果表明:碳酸钙的加入可以显著升高酸性红壤的p H,土壤溶液中铝、锰和镁浓度显著低于未加碳酸钙处理;800 mg/kg磷处理后铝、锰、镁和钙的浓度要比未加磷处理分别至少降低47%、44%、37%和33%。随着施磷量的增加,小麦在200 mg/kg磷处理时积累的生物量最大,随后磷增加,小麦生物量反而降低。而加碳酸钙处理小麦地下部生物量随着施磷量增加则降低。结果表明碳酸钙不仅可以有效升高土壤p H,降低土壤溶液铝浓度,还降低土壤溶液中锰的浓度。磷的加入同样可以降低锰和铝的浓度,缓解铝和锰毒害。红壤中生长小麦的适宜施磷量为200 mg/kg。

Effects of Different Phosphorus Rates on Variations of Mn, Al, Mg and Ca Concentrations in Soil Solution and Wheat Growth in Acid Red Soil

To investigate the effects of different phosphorus rates on the variations of Mn, Al, Mg and Ca concentrations in soil solutions and wheat responses to phosphorus in acid red soil, a pot experiment with a non-destructive soil-solution sampler preinstalled were conducted with increasing phosphorus fertilizer levels from 0 to 800 mg/kg. The results showed that pH was increased while the concentrations of Mn, Al, Mg and Ca in soil solutions were significance lower amended with CaCO₃ than without CaCO₃. Compared to 0 mg/kg phosphorus treatment the concentrations of Al, Mn, Mg and Ca at least decreased 47%, 44%, 37% and 33% after 800 mg/kg phosphorus treatment no matter amended with CaCO₃ or not. Wheat biomass was accumulated highest in 200 mg/kg phosphorus treatment then decreased as phosphorus rates increased. However, the root biomass trended to decline as phosphorus rate increased while the soil was amended with CaCO₃. Those results indicated that CaCO₃ could increase pH and decrease Mn, Al and Mg concentrations in soil solution. At the same time, phosphorus could alleviate Mn and Al toxicities in acid red soils while decrease Mn and Al concentrations in soil solution. 200 mg/kg phosphorus fertilizer was suitable for wheat growth in acid red soil.