Originally Posted by
Gipsy
You can, let's say within a radius of a meter, carefully cut/remove the weeds around the saplings, then mark the young plants with a bamboo stick and a bit of color on top.
Then send in a small tractor, or a few guys with their brush cutters/horizontal mowers. As a last resort use the weedkiller, either vinegar based or the nasty stuff; Glyphosate 48, it is a formula that will not kill other plants than weed. To make sure you can test it on a few saplings but 17 rai might take a while to spray, not to mention the costs.
Animals is not an option, the saplings will either be eaten or knocked over by them.
Good luck!