Beijing Key Laboratory of Farmyard Soil Pollution Prevention-control and Remediation, College of Resources and Environmental Sciences, China Agricultural University, Beijing, 100193, China.
Teagasc, Environmental Research Centre, Johnstown Castle, Co. Wexford, Ireland.
Environ Pollut. 2020 Jun;261:114175. doi: 10.1016/j.envpol.2020.114175. Epub 2020 Feb 13.
In China, excessive phosphorus (P) application in protected vegetable fields has led to high legacy P stores. Soil amendment with alum or dolomite is one of many best management practices (BMPs) used to reduce P losses in calcareous soils. However, both the kinetics and mechanisms of P sorption and soil available P in amended soils are understudied. Herein, both aspects were looked at under controlled conditions. Firstly, a sorption study which coupled P concentrations with poorly-crystalline Al hydroxides and dolomite was conducted. Results from this batch experiment showed that P sorption on poorly-crystalline Al hydroxides was homogenous and occurred mainly via displacement of inner-sphere hydroxyl (Al-OH) instead of the formation of AlPO. However, the amount of sorbed P reached maximum sorption of 73.1 mg g and did not change with further increase in P concentration. It was observed that P adsorbed onto the dolomite surface at low P concentrations, whereas hydroxyl replacement and uneven cluster precipitation of Ca(PO) occurred at high P concentrations. A second 90 day incubation experiment investigated changes to soil available P and sorption-desorption across variable rates of amendments (0-50 g kg). Results showed that alum amendment at a rate of 50 g kg decreased soil CaCl-P and Olsen-P concentrations by 91.9% and 57.8%, respectively. However, Olsen-P increased when the dolomite rates were <20 g kg. Phosphorus sorption-desorption of the amended soil showed alum had higher P sorption efficiency than dolomite at low addition rates (<10 g kg). However, soil amended with high dolomite rates (>10 g kg) could sorb more P in comparison with alum when P concentrations were increased. The P status of the amended soil was closely connected to the P sorption mechanisms on mineral amendments, soil P concentrations and soil properties.
在中国，保护地蔬菜田过量施用磷（P）导致了大量的磷残留。用明矾或白云石进行土壤改良是减少石灰性土壤中磷损失的许多最佳管理实践（BMP）之一。然而，改性土壤中磷的吸附动力学和机制以及土壤有效磷都研究不足。在此，在受控条件下研究了这两个方面。首先，进行了耦合磷浓度与无定形 Al 氢氧化物和白云石的吸附研究。该批实验结果表明，无定形 Al 氢氧化物上的磷吸附是均匀的，主要通过内圈羟基（Al-OH）的取代而不是 AlPO 的形成发生。然而，吸附的磷量达到最大吸附量 73.1mg/g，并且不会随着磷浓度的进一步增加而改变。观察到，在低磷浓度下，磷吸附在白云石表面，而在高磷浓度下，羟基取代和 Ca(PO)不均匀团簇沉淀发生。第二个 90 天的培养实验研究了不同改良剂（0-50g/kg）速率下土壤有效磷和吸附-解吸的变化。结果表明，以 50g/kg 的速率添加明矾可分别降低土壤 CaCl-P 和 Olsen-P 浓度 91.9%和 57.8%。然而，当白云石用量<20g/kg 时，Olsen-P 增加。添加土壤的磷吸附-解吸表明，在低添加率（<10g/kg）下，明矾比白云石具有更高的磷吸附效率。然而，当磷浓度增加时，与明矾相比，高白云石用量（>10g/kg）添加的土壤可吸附更多的磷。添加土壤的磷状况与矿物改良剂上的磷吸附机制、土壤磷浓度和土壤特性密切相关。
