Buckwheat Cover Crop Handbook
Expected benefits
These procedures are based on well-established principles, on experimental verification, and on testing by many commercial growers. This section describes why each procedure works and what you might expect as a result.
Goals:
Suppress summer annual weeds. Seeds of summer annual weeds germinate but are suppressed, which reduces next year’s weed seed bank. A strong stand of buckwheat suppresses all summer annuals. Weeds should be very rare and only a few inches tall. If the buckwheat starts growing slowly, or there are gaps, the weeds that most often escape are redroot pigweed, lambsquarters, and barnyardgrass. Buckwheat is a strong suppressor of ragweed and purslane. It does not control weeds after it has been killed.
Reduce perennial weeds. Some perennial weeds, especially quackgrass, are weakened by midsummer tillage and recover poorly in a stand of buckwheat.
Improve soil condition. Buckwheat improves soil aggregation through secretions from its extensive network of fine roots, which leaves the soil mellow. The effect is fairly short-lived, so it is worth taking advantage of with the following crop. The mellowing can be stabilized by following with an aggregate-stabilizing crop, such as ryegrass, that has a large mycorrhizal root system.