A device for mechanical remediation of degraded grasslands

Conventional tillage practices are traditional methods to restore the degraded grasslands. However, the risk of wind and water erosion increases dramatically. To remedy these degraded grasslands and conserve soil and water, a rotary cutting mechanism named soil-gashing and root-cutting device was designed and tested in typical degraded grassland. The grass specie was leymus-chinensis, which is the main forage in Northern China. This device consisted of eight sets of cutting tools, and each set of tools had three identical crescent cutting blades. It can create consecutive openings in compacted soil. These openings provided soil aeration and promoted the growth of leymus-chinensis. Field experiments indicated that the maximum cutting depth was 200 mm while the average width of slits was 12.8 mm. No soil overturning was observed. To reduce the torque required to drive this cutting mechanism, the crescent cutting blade was optimized through indoor soil bin tests. Field tests were then conducted to evaluate the effect of this cutting mechanism on the soil physical and chemical properties and the crop yield of a degraded grassland. Results showed that soil organic matter and total nitrogen were significantly increased in the second year of soil-gashing and root-cutting treatment, and the soil pH value was reduced to the suitable level for the growth of leymus-chinensis. The soil bulk density was reduced, and the soil porosity increased after a one-year period though these changes were not statistically significant. Grass yield was increased by 94.8% in the second year.