College of Resources and Environment, Yunnan Agricultural University, Kunming, 650201, China; Agricultural Environment and Resources Institute, Yunnan Academy of Agricultural Sciences, Kunming, 650201, China.
College of Resources and Environmental Sciences, State Key Laboratory of North China Crop Improvement and Regulation, Hebei Province Key Laboratory for Farmland Eco-Environment, Hebei Agricultural University, Baoding, 071000, China.
J Environ Manage. 2024 Aug;366:121744. doi: 10.1016/j.jenvman.2024.121744. Epub 2024 Jul 5.
The continuous excessive application of phosphorus (P) fertilizers in intensive agricultural production leads to a large accumulation of P in surface soils, increasing the risk of soil P loss by runoff and leaching. However, there are few studies on the accumulation and loss of P from surface soil to deep soil profiles driven by shallow groundwater table (SGT) fluctuations. This study used the intensive cropland around 7 plateau lakes in Yunnan Province as an example and conducted in situ monitoring of P storage in the soil profile and SGT during the rainy season (RS) and dry season (DS) as well as simulation experiments on soil P loss. The aim was to study the spatiotemporal variation in P accumulation in the soil profile of cropland driven by SGT fluctuations in the RS and DS and estimate the P loss in the soil profile driven by SGT fluctuations. The results showed that fluctuations in the SGT promoted P accumulation from the surface soil to deeper soil. The proportions of P stored in various forms in the 30-60 cm and 60-100 cm soil layers in the RS were greater than those in the DS, while the average proportion in the 0-30 cm soil layer in the DS was as high as 48%. Compared with those in the DS, the maximum decreases in the proportion of P stored as TP and Olsen-P in the 0-100 cm soil layer in the RS were 16% and 58%, respectively, due to the rise in the SGT (SGT <30 cm), while the soil TP storage decreased by only 1% when the SGT was maintained at 60-100 cm. The critical thresholds for soil Olsen-P and TP gradually decreased with increasing soil depth, and the risk of P loss in deeper soil increased. The loss of soil P was increased by fluctuations in the SGT. Based on the cropland area around the 7 plateau lakes, P storage, and SGT fluctuations, the average loss intensity and loss amount of TP in the 0-100 cm soil layer around the 7 plateau lakes were estimated to be 25 kg/ha and 56 t, respectively. Therefore, reducing exogenous P inputs, improving soil endogenous P utilization efficiency and maintaining deep soil P retention are the basic strategies for preventing and controlling P accumulation and loss in deep soil caused by SGT fluctuations.
集约化农业生产中磷（P）肥的持续过量施用导致表层土壤中 P 的大量积累，增加了通过径流和淋溶损失土壤 P 的风险。然而，对于由浅层地下水位（SGT）波动驱动的表层土壤向深层土壤剖面中 P 的积累和损失，研究较少。本研究以云南省 7 个高原湖泊周围集约化农田为例，在雨季（RS）和旱季（DS）进行原位监测土壤剖面中 P 储量和 SGT，并进行土壤 P 损失模拟实验。目的是研究 RS 和 DS 期间 SGT 波动驱动的农田土壤剖面中 P 积累的时空变化，并估算 SGT 波动驱动的土壤剖面中 P 损失。结果表明，SGT 波动促进了 P 从表层土壤向深层土壤的积累。RS 中 30-60cm 和 60-100cm 土层中各形态 P 储存比例大于 DS，而 DS 中 0-30cm 土层中平均比例高达 48%。与 DS 相比，RS 中 0-100cm 土层中 TP 和 Olsen-P 储存比例的最大降幅分别为 16%和 58%，这是由于 SGT 上升（SGT<30cm）所致，而当 SGT 保持在 60-100cm 时，土壤 TP 储存仅减少 1%。土壤 Olsen-P 和 TP 的临界阈值随土壤深度的增加而逐渐降低，深层土壤的 P 损失风险增加。SGT 波动会增加土壤 P 的损失。基于 7 个高原湖泊周围农田面积、P 储量和 SGT 波动，估计 7 个高原湖泊周围 0-100cm 土壤层中 TP 的平均损失强度和损失量分别为 25kg/ha 和 56t。因此，减少外源 P 投入、提高土壤内源 P 利用效率和维持深层土壤 P 保持是防止和控制 SGT 波动引起的深层土壤 P 积累和损失的基本策略。
