Abstract: A field plot experiment was conducted to examine the effectiveness of equidistant slotting in combining with gypsum application on the amelioration of soda saline-alkali soil in the west Songnen Plain of Northeast China. Equidistant slotting at the soil depth 20-40 cm and 1 m apart could significantly decrease the degree of soil compaction within the slotted area, as compared with the control (un-slotting), and also, had definite effect in decreasing the soil compactness between the slotted areas. Slotting combined with gypsum application improved the soil chemical properties, with significant difference in soil pH and exchangeable sodium percentage but little difference in soil electrical conductivity between gypsum and nogypsum treatments. Slotting and subsoiling had little effects on soil chemical properties within the slotted areas. Phosphogypsum and desulfurized gypsum had little difference in ameliorating the soda saline-alkali soil. This study showed that slotting in combining with gypsum application could effectively improve the physical and chemical properties of soda saline-alkali soil and the plant growth within the slotted area, and had definite effect in ameliorating soil properties and in promoting plant growth between the slotted areas.

Key words: Weibei Highlands, winter wheat, conservation tillage, WinEPIC, soil moisture.