Holding back weeds

When tilling is stopped number of weeds decreases considerably especially when there is enough decomposed mulch on the surface. I had seen this after growing sunhemp in one part of the farm and after summer, all the cover crop and grass had dried and surface was clean. This happens especially after summer with no artificial irrigation given, if irrigation was given in the summer, grass will be there all around and starting cultivation in the next rainy season is difficult.

We should start putting the seeds before the grass starts coming after the rains. If seeds are put and if they over crowd, then weeds will be held back. But if we the process of putting seeds is delayed, then grass take over and cultivation becomes difficult.