To halt desertification the number of animals on the land must be reduced, allowing plants to regrow. Soil conditions must be made favourable for plant growth by, for example, mulching. Mulch reduces evaporation, suppresses weed growing, enriches soil , and prevents run-off and hence erosion. Reseeding may be necessary in badly degraded areas.
But the most important thing to prevent desertification is through good land management in semi-arid areas.