The type of straw used often depends on availability. In order to get clean straw and bales of appropriate size growers will establish contracts with grain producers. In some areas of the province rye straw is the most easily available material for mulching. Using rye as a straw mulch in ginseng can carry a risk of allelopathy. These chemicals, called allelochemicals, escape into the environment and influence the development of neighbouring plants.
Rye is a common rotational crop that is known to suppress weed growth through rapid competition.
Rye also manufacturers allelochemicals that inhibit the germination and growth of a number of plants. Rye residues also have this property. It is a property that is very useful in suppressing weeds. Under certain weather conditions rye straw can be allelopathic to ginseng. In straw mulch there are about 2-3 bushels of kernels of grain.