Thoroughly cultivate the land and water it and allow all the seeds in the land to germinate. once we are sure that most of the seeds are germinated then cultivate once again. Now we are sure that most of the seed based weeds are eradicated. Sowing of plants can be done now. After the sprouts have come out to a height of 3 inches in case of seed and immediately in case of transplanting the nursery, mulching with hay or any other plantwaste material. Whatever grass comes, which is rootbased should be handled by manually, if it grows beyond the height of the crop. Otherwise should be ignored as it is not going to harm the plants in any way. More over it acts as live mulching and keep the soil loose by spreading its roots in all directions. This will eliminate the weed problem. I HAVE COME TO KNOW THIS FROM PADMASRI SUBHASH PALEKAR
Regards
M VENKATA SUBBARAO