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.
J Environ Sci (China). 2021 Mar;101:87-97. doi: 10.1016/j.jes.2020.08.007. Epub 2020 Aug 24.
High phosphorus (P) saturation arising from historic P inputs to protected vegetable fields (PVFs) drives high P mobilisation to waterbodies. Amendment of soils with alum has shown potential in terms of fixing labile P and protecting water quality. The present 15 month pot experiment investigated P stabilisation across single alum application (Alum-1 treatment, 20 g alum/kg soil incorporated into soil before the maize was sown), alum split applications (Alum-4 treatment, 5 g alum/kg soil incorporated into soil before each crop was sown i.e. 4 × 5 g/kg) and soil only treatment (Control). Results showed that the Alum-1 treatment caused the strongest stabilisation of soil labile P after maize plant removal, whereas the P stabilisation effect was gradually weakened due to the transformation of soil non-labile P to labile P and the reduced active Al in soil solution. For the Alum-4 treatment, soil labile P decreased gradually with each crop planting and was lower than the Alum-1 treatment at the end of the final crop removal, without any impairment on plant growth. The better P stabilisation at the end of Alum-4 treatment was closely correlated with a progressive supply of Al and a gradual decrease of pH, which resulted in higher contents of poorly-crystalline Al, Fe and exchangeable Ca. These aspects were conducive to increasing the soil P stabilisation and phosphate sorption. In terms of management, growers in continuous cropping systems could utilise split alum applications as a strategy to alleviate P losses in high-P enriched calcareous soil.
历史上向保护菜地（PVFs）输入的高磷（P）饱和度导致大量 P 向水体迁移。土壤中添加明矾在固定活性 P 和保护水质方面具有潜力。本 15 个月的盆栽实验研究了单次施用明矾（Alum-1 处理，在播种玉米之前将 20g 明矾/kg 土壤掺入土壤中）、明矾分次施用（Alum-4 处理，在每次播种之前将 5g 明矾/kg 土壤掺入土壤中，即 4×5g/kg）和仅土壤处理（对照）对 P 稳定化的影响。结果表明，在玉米植物移除后，Alum-1 处理对土壤活性 P 的稳定化作用最强，而由于土壤非活性 P 向活性 P 的转化和土壤溶液中活性 Al 的减少，P 稳定化效果逐渐减弱。对于 Alum-4 处理，随着每次种植作物，土壤活性 P 逐渐减少，在最后一次作物移除时低于 Alum-1 处理，但对植物生长没有任何影响。Alum-4 处理结束时更好的 P 稳定化与 Al 的逐步供应和 pH 的逐渐降低密切相关，这导致了较差结晶 Al、Fe 和可交换 Ca 的含量增加。这些方面有利于增加土壤 P 稳定化和磷酸盐吸附。在管理方面，连续种植系统中的种植者可以利用明矾分次施用作为减轻富钙土壤中 P 损失的策略。
