The impact of irrigation water quality on soil properties in vegetable-growing areas of Gia Lam, Hanoi

Abstract

The research was conducted through pot experiments in a greenhouse combined with random sampling in the Cau Bay river irrigation area to compare soil characteristics before and after three experimental seasons using different types of water: treated domestic wastewater, Cau Bay river water, and well water supplemented with chemical fertilisers for several leafy vegetables grown on Red river alluvial soil in Gia Lam (Hanoi). The results showed that irrigation with wastewater and Cau Bay river water increased soil nitrogen (N), phosphorus (P), and organic matter contents. Soil pH, moisture, and nutrient levels were all improved compared with well water irrigation. However, with regular irrigation using Cau Bay river water, the accumulated N and P content in the soil was 1.4 to 1.5 times higher than with well water irrigation. This poses a potential risk of nitrate accumulation in soil and vegetables if nutrient balance among irrigation water, soil, and fertilisers is not adequately controlled.