Agricultural use of deserted saline land through an optimized drip irrigation system with mild salinized water

It was necessary and challenging to utilize the saline-alkali land in coastal region for agricultural development. To desalinate salty lands for potential crop cultivation, a two-year field experiment with an optimized tillage under a drip irrigation with five levels of salty water (ECw = 0.7, 3.2, 4.7, 6.2, 7.8 dS m-1, respectively) was conducted in the Bohai Rim region, China. Results showed that, following an enhanced leaching, the soil moisture content with each treatment increased significantly throughout the whole soil profile while soil salinity within the main root zone dropped by 52.5 +/- 3.8 % with no obvious differences among treatments. Throughout the regular leaching/irrigation period, the soil matric potential (SMP) was often below the threshold of -5 kPa during the primary water consumption stage of tomato plants, and the salt leaching efficiency was lower than that during the enhanced leaching period and the salt leaching rate within the main root zone decreased linearly as the ECw increased. Final measurements at the end of the experiment, the soil salinity and the sodium adsorption ratio of the main root zone declined by 87.1-94.7 % and 58.4-63.7 %, respectively; while the reduction rate of soil cations ranged from 98.8 % to 89.5 %, following the order of Mg2+ > Ca2+ > K+ > Na+, indicating that leached saline soil around root zones were suitable for tomato cultivation. Thus, we recommend that (1) a larger irrigation quota be applied (e.g., 10 mm/watering) or a rigid irrigation program be scheduled according to SMP with no limit on daily maximum irrigation times; (2) two irrigation modes and a three-stage irrigation management scheme be used for tomato planting in coastal silt salt-affected lands for an ultimate yield.