How can farmers reduce soil erosion?

Basically farmers have to plant lot of trees at the boundary of their field (specially neem trees).its roots will hold the soil properly and prevent its erosion.

There are two major causes of erosion, wind and water. While wind erosion is fairly well addressed by windbreaks, reducing water caused erosion requires leaving land covered. The impact of rain drops is the primary caused of soil particle detachment. Leaving crop residue on the surface breaks this impact. Cover crops also help by providing cover and feeding soil life. In healthy soils microbes add naturally sticky substances that help improve the stability of soils; they glue the particles together. The best way to get both the residue coverage and microbial glues is to totally eliminate tillage of the soil. Called no till agriculture, this system plants through crop residues with minimal disturbance. As soil health improves, the soils are able to absorb more water, further reducing erosion.