Hairy vetch and crimson clover develop faster than many other legumes and are recommended as catch crops after early potatoes. Unfortunately, their seeds are expensive and they will fix as little as one fifth the nitrogen of a spring sowing. In several countries, rye has been the most popular cover or rotation crop for potatoes, especially for light soils. Unlike legumes, it does not need a high pH and is very competitive with weeds. It is one of the best plants to prevent nitrate leaching in the fall.
Rye is also very tolerant of low winter temperatures.
Unfortunately, rye is difficult to kill in the spring and it can be a host for nematodes that attack potatoes. As a cash crop, rye has a limited market in Eastern Canada, although it can be used as animal feed. Rye is also very susceptible to ergot. Before potatoes Rye can be planted after another cereal crop. Since it is not winter killed, it needs to be destroyed the following spring by tillage or herbicides.