Enhancing Soil Health Through Sediment Deposition in Flood‐Based Agricultural Systems: Evidence From the Mekong Delta, Vietnam

Sediment deposition in the Vietnamese Mekong Delta (VMD) has declined sharply due to high‐dike infrastructure and upstream damming, threatening long‐term soil fertility and agroecosystem resilience. This study presents the first integrated assessment of sediment dynamics and soil health across four flood‐based and conventional agricultural systems in VMD. We compared sediment accumulation and soil biochemical properties in (1) floating rice–fish farming, (2) lotus–fish farming, (3) natural flooding, and (4) triple‐rice cropping systems. Sediment samples ( n = 80) and soil samples ( n = 35) were collected from 2022 to 2024. We applied principal component analysis (PCA) to identify a minimum data set of soil indicators and used a weighted soil health index (SHI) to evaluate system performance. Nonparametric Kruskal–Wallis tests revealed statistically significant differences in sediment mass, nutrient retention, and soil health among models ( p < 0.001). The lotus–fish and natural flooding models exhibited 8–15 times greater sediment deposition and SHI values that were 25%–33% higher than those of the triple‐rice system, with strong correlations between sediment mass and soil health ( R 2 = 0.613). These models also enable reductions of up to 40% in postflood nitrogen and potassium fertilizer requirements. Using PCA and a weighted SHI framework, we highlight that flood‐based systems, particularly lotus–fish farming, significantly enhance soil health and reduce fertilizer dependency. Our results support the scaling of sustainable agricultural transitions in line with Vietnam’s Resolution 120 on climate‐resilient development in the VMD.