asked:
Organic herbicides can be used in organic gardening and farming to weaken or kill unwanted plants, otherwise known as weeds.
Selective herbicides are used to manage weeds that are either growing in between rows of crops, or to kill moss and weeds in lawns. Non-selective herbicides are used in areas where no plants are wanted, such as a gravel path. They may also be used to destroy remains of plants after a crop has finished.
Most organic herbicides are non-selective, i.e. they destroy all plants, without leaving residues in the soil that would prevent another crop from being grown in the next season. Generally they will also not harm the worms, beneficial bacteria and fungi that are a vital part of the life of the soil. Many non-organic weed killers will harm these forms of life and therefore weaken the growing power of the land.
Although technically speaking an organic herbicide could be any weed killer that includes carbon, which is almost all of them, these days the term has come to mean herbicides that are approved for use on organic land. This can vary in different jurisdictions so if organic certification is important to you (for example if you are selling your produce as organic) you will need to check with the appropriate state agency.