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A soil-gashing and root-cutting mechanism was designed and tested in order to improve degenerated Leymus-chinensis grassland in China. The mechanism had eight equally-spaced sets of cutting blades on a blade shaft, and each set consisted of 3 blades. These blades were keyed on the blade shaft as double-helical arrangement through flange hubs. The blade on the shaft was powered by a final drive which was driven by a universal shaft connected to the tractor PTO. Cutting depth was controlled from 100mm to 200mm by two gauge wheels mounted on the rear end of the tool frame. Field experiment indicated that the mechanism could cut consecutive slits in compacted top soil. The maximum cutting depth was 205mm and the average width of slits was below 13mm. No soil overturning and vegetation destruction were observed. Because the slits cut by the mechanism provided soil aeration and promoted the growth of Leymus-chinensis, the soil bulk density decreased and crop yield increased by nearly double in the second year of soilgashing and rootcutting treatment.