Effects of Irrigation Water Salt Compositions on Tomato Growth and Soil Salinization

Abstract

[Objective] To explore the optimal salt composition and salt concentration of irrigation water suitable for tomato field cultivation in arid and semi-arid areas. [Methods] Three salinity levels (1, 2, and 3 g/L) and five Na∶Ca molar concentration ratio levels (1, 3, 5, 7, and 9) of irrigation water were used in a 3-year field experiment of drip irrigation under tomato film in Yinbei irrigation district of Ningxia, China. [Results] The experiment found that with lower irrigation water salinity (1 g/L), appropriate increases in the Na∶Ca molar ratio of irrigation water were beneficial for the accumulation of tomato plant dry matter and nutrients. Tomato fruit weight, marketable yield, and total yield decreased linearly with the increase of irrigation water Na∶Ca molar ratios. Moreover, with each increase in Na∶Ca molar ratio of irrigation water, the tomato marketable yield decreased by 5 761.7 to 6 036.7 kg/hm2. Irrigation water with “high salinity (2, 3 g/L) and low Na∶Ca molar ratio (1 and 3)” was more profitable for tomato yield increase than irrigation water with “low salinity and high Na∶Ca molar ratio”. The soil sodium adsorption ratio in 0—40 cm and the amount of soil salt accumulation in 0—100 cm increased linearly with the increase of irrigation water Na∶Ca molar ratio. [Conclusion] To alleviate the soil salt accumulation and obtain a relatively high fruit yield during the growth period of field cultivated tomatoes in Yinbei irrigation area of Ningxia, irrigation water with salinity of 2 g/L and Na∶Ca molar concentration ratio of 5 was recommended for mulched drip irrigation, under the control limit of soil matrix potential at -20 kPa.

Keywords

• saline water
• mulched drip irrigation
• dry matter accumulation
• marketable yield
• sodium adsorption ratio