Lasisi Ahmed, Weerasekara Chamara S, Kumaragamage Darshani, Akinremi Olalekan O
Department of Environmental Studies and Sciences, The University of Winnipeg, Winnipeg, Manitoba, Canada.
Swift Current Research and Development Centre, Agriculture and Agri-Food Canada, Swift Current, Saskatchewan, Canada.
J Environ Qual. 2023 May-Jun;52(3):718-729. doi: 10.1002/jeq2.20469. Epub 2023 Mar 30.
The effectiveness of amendments such as alum [Al (SO ) ·18H O] in reducing phosphorus (P) loss to floodwater has been reported under summer conditions and laboratory-controlled environments, but not under actual spring weather conditions in cold climate regions with high diurnal temperature variations when potential for P losses is high. The effectiveness of alum in reducing P release under Manitoba spring weather conditions was evaluated in a 42-day experiment using 15-cm soil monoliths from eight agricultural soils, which were unamended or alum-amended (5 Mg ha ) and flooded to a 10-cm head. Dissolved reactive P (DRP) concentrations and pH of porewater and floodwater were determined on flooding day and every 7 days after flooding (DAF). Porewater and floodwater DRP concentrations in unamended soils increased 1.4- to 4.5-fold, and 1.8- to 15.3-fold, respectively, from 7 to 42 DAF. In alum-amended soils, DRP concentrations averaged across soils was 43%-73% (1.0-2.0 mg L ) lower in porewater, and 27%-64% (0.1-1.2 mg L ) lower in floodwater than unamended soils during the flooding period. The reduction of DRP by alum was more pronounced under high fluctuating diurnal spring air temperature than with controlled air temperature (4°C) in a previous similar study. Acidic pH in porewater and floodwater due to alum did not persist over 7 days. This study showed that alum application is a viable option in reducing P released to floodwater in agricultural soils of cold regions where flooding-induced P loss is prevalent in the spring.
据报道，诸如明矾[Al(SO₄)₃·18H₂O]之类的改良剂在夏季条件和实验室控制环境下可有效减少磷（P）流失到洪水中，但在昼夜温差大、磷流失可能性高的寒冷气候地区的实际春季天气条件下却并非如此。在一项为期42天的实验中，使用来自八种农业土壤的15厘米土壤柱体评估了明矾在曼尼托巴省春季天气条件下减少磷释放的效果，这些土壤柱体未改良或用明矾改良（5 Mg/ha），并将水位抬高至10厘米。在浸水日以及浸水后每7天（DAF）测定孔隙水和洪水的溶解性活性磷（DRP）浓度以及pH值。未改良土壤中孔隙水和洪水的DRP浓度在浸水7至42天期间分别增加了1.4至4.5倍和1.8至15.3倍。在浸水期间，与未改良土壤相比，明矾改良土壤中孔隙水平均DRP浓度低43%-73%（1.0-2.0 mg/L），洪水DRP浓度低27%-64%（0.1-1.2 mg/L）。与之前类似研究中4°C的受控气温相比，在春季昼夜气温波动较大的情况下，明矾对DRP的降低作用更为明显。由于明矾导致的孔隙水和洪水的酸性pH值在7天内并未持续。这项研究表明，在春季因洪水导致磷流失普遍的寒冷地区的农业土壤中，施用明矾是减少磷释放到洪水中的可行选择。
