AgResearch, Lincoln Research Centre, Lincoln, Canterbury, 7647, New Zealand.
AgResearch, Lincoln Science Centre, Private Bag 4749, Christchurch, 8140, New Zealand.
J Environ Qual. 2020 Jul;49(4):1054-1061. doi: 10.1002/jeq2.20086. Epub 2020 Jun 1.
Cadmium (Cd) can accumulate in soil from the application of phosphorus fertilizer. However, there is little information on what happens to soil Cd concentrations when Cd inputs stop. This study used soil and pasture samples collected from a long-term field trial to measure changes in Cd concentrations in soil for 22 yr after Cd inputs from fertilizer had stopped and assessed whether the application of nitrogen (N) (50 kg ha yr ) could increase plant uptake of Cd and reduce soil Cd concentrations. It was found that there was no significant change in total or labile soil Cd (1 M CaCl extractable) concentrations after Cd inputs stopped. The application of N did not significantly (P < .05) increase dry matter yield or increase Cd solubility. As a result, N did not enhance plant uptake of Cd. A mass balance that included Cd loss via plant uptake and Cd leaching confirmed they were insufficient to result in a detectable decrease in soil Cd concentration over the 22-yr interval of the trial. It appears that even an acid soil with low amounts of carbon (2.67%), iron/aluminum oxides, and clay can still strongly retain Cd, preventing Cd depletion from the soil, despite stopping Cd inputs and trying to enhance plant uptake of Cd from the application of N fertilizer.
镉（Cd）可以通过施加磷肥在土壤中积累。然而，当停止镉输入时，土壤中镉浓度会发生什么变化，这方面的信息却很少。本研究利用长期田间试验采集的土壤和牧草样本，在停止肥料镉输入 22 年后测量土壤中镉浓度的变化，并评估施氮（N）（50kg ha -1 yr -1 ）是否可以增加植物对镉的吸收并降低土壤镉浓度。结果发现，停止镉输入后，土壤总镉和可提取镉（1M CaCl 提取）浓度没有明显变化。施氮并未显著（P <.05）增加干物质产量或增加镉的溶解度。因此，氮并没有增强植物对镉的吸收。包括植物吸收和镉淋失导致的镉损失的质量平衡表明，在试验的 22 年期间，它们不足以导致土壤镉浓度的可检测降低。即使是一种酸性土壤，其碳（2.67%）、铁/铝氧化物和粘土含量较低，仍能强烈保持镉，防止土壤中镉的耗尽，尽管停止了镉的输入并试图通过施加氮肥来增强植物对镉的吸收。
