Ngan Nguyen Vo Chau, Thao Huynh Van, Giang Nam Nguyen Dinh
Department of Water Resources - College of Environment and Natural Resources, Can Tho University, Can Tho city, 900000, Vietnam.
Department of Environmental Science - College of Environment and Natural Resources, Can Tho University, Can Tho city, 900000, Vietnam.
F1000Res. 2023 Jan 5;10:1145. doi: 10.12688/f1000research.73904.2. eCollection 2021.
The evaluation of nutrient variability plays a crucial role in accessing soil potentials and practical intervention responses in rice production systems. Synthetic fertilizer applications and cultivation practices are considered key factors affecting nutrient dynamics and availability. Here, we assessed the nutrient dynamics in surface, subsurface water and soil under local water management and conventional rice cultivation practices in the Vietnamese Mekong Delta. We implemented a field experiment (200 m ) in the 2018 wet season and the 2019 dry season in a triple rice-cropping field. Eight samples of surface water, subsurface water (30-45 cm), and topsoil (0-20 cm) were collected and analysed during the rice-growing seasons. The results showed that N-NH , P-PO and total P peaks were achieved after fertilizing. Irrespective of seasons, the nutrient content in surface water was always greater than that of subsurface water ( < 0.001), with the exception of N-NO , which was insignificant ( > 0.05). When comparing the wet and dry seasons, nutrient concentrations exhibited minor differences ( > 0.05). Under conventional rice cultivation, the effects of synthetic fertilizer topdressing on the total N, soil organic matter (SOM), and total P were negligible in the soil. Higher rates of N fertilizer application did not significantly increase soil N-NH , total N, yet larger P fertilizer amounts substantially enhanced soil total P ( < 0.001). Under conventional rice cultivation, N-NH , P-PO and total P losses mainly occur through runoff rather than leaching. While N-NO loss is similar in surface water and subsurface water. Notably, nutrient content in soil was high; whilst SOM was seen to be low-to-medium between seasons. Future work should consider the nutrient balance and dynamic simulation in the lowland soil of the Vietnamese Mekong Delta's paddy fields.
养分变异性评估在挖掘水稻生产系统的土壤潜力和实际干预响应方面起着关键作用。施用合成肥料和种植方式被认为是影响养分动态和有效性的关键因素。在此，我们评估了越南湄公河三角洲当地水管理和常规水稻种植方式下地表水、地下水和土壤中的养分动态。我们于2018年雨季和2019年旱季在一块三季稻种植田开展了一项田间试验（200平方米）。在水稻生长季节采集并分析了8个地表水、地下水（30 - 45厘米）和表层土壤（0 - 20厘米）样本。结果表明，施肥后铵态氮、磷酸根磷和总磷出现峰值。无论季节如何，除了硝态氮差异不显著（P > 0.05）外，地表水的养分含量总是高于地下水（P < 0.001）。比较雨季和旱季时，养分浓度差异较小（P > 0.05）。在常规水稻种植下，土壤中追施合成肥料对全氮、土壤有机质（SOM）和总磷的影响可忽略不计。较高的氮肥施用量并未显著增加土壤铵态氮、全氮，但大量施用磷肥显著提高了土壤总磷（P < 0.001）。在常规水稻种植下，铵态氮、磷酸根磷和总磷的损失主要通过径流而非淋溶发生。而硝态氮在地表水和地下水中的损失情况相似。值得注意的是，土壤中的养分含量较高；而季节间SOM含量为低至中等。未来的工作应考虑越南湄公河三角洲稻田低地土壤中的养分平衡和动态模拟。
