A Natural Farming System For Sustainable Agriculture In the Tropics Sustainable Agriculture Book - Chapter 12 Mulching
Mulching is Fundamental #6. It will conserve topsoil and moisture, as well as provide fertilizer. When straw or crop residue covers the topsoil, it holds it in place while stopping raindrops from compacting soil. Areas with heavy rain require more plowing.
It also slows down rain run off so that moisture can penetrate down to the roots. Erosion is costing farmers valuable organic matter and trace elements. When you mulch, the rain percolates gently into the soil and goes much deeper than when exposed to wind and rain. In dry climates wind erosion can be worse than rain erosion.