Saline water seepage from drainage canals induces soil salinizaton and growth depression in the adjacent cornfields in the upper yellow river basn

In order to analyze the growth of corn plants and the level of salinization in and around an irrigated field in the Yellow River basin, surveys of plant growth, soil and water quality were conducted in August and September 2007. Plant growth parameters such as height, leaf nitrogen content and maximum quantum yield of photosystem I (Fv/Fm), and chemical characteristics of the Yellow River water, irrigation canal water, ground water, drainage canal water, saline seep water and field soils were measured. There was a significant difference in corn growth in the irrigated field, that is, plant height, leaf nitrogen content and Fv/Fm decreased as the drainage canal for removing the saline seep water was approached. The electrical conductivity (EC) and various dissolved ion concentrations of the ground water in the field exhibited remarkable high values compared to those of the Yellow River water and the irrigation canal water. When a comparion between three survey points in the field (the nearest, middle and the farthest to the drainage canal) was made, it became clear that there existed clear gradients of those concentrations, that is, they showed the highest values at the nearest point and caused the poorest growth of corn plant at the point. The EC and ion concentrations of the saline seep at the foot of the river terrace made of loess showed extremely high values. The drainage canal for removing the seep water, which separated the survey field and the terrace, was not lined and hence the salty water in this canal seemed to seep into the surounding fields. These results obtained from his study suggest that the cultivation system such as irrigation techniques and drainage facilities should be improved for sustaining productive irirrigated agriculture in this area.