Almost any agricultural species can have some potential green manuring effect. Some are more widely used than others.

The characteristics of ultimate green cover crops would be:

Suppression of weeds
Preventing leaching of soil nutrients
Improvement of fertility by increasing nutrient levels and organic matter
Reduction of pest and disease risk in following crops
NOT to introduce volunteer weeds
Require limited maintenance
Choice of crop depends upon the length of time it will be in the ground, the date of sowing and disease risk in any rotation.

Pests and diseases

The choice of green cover crop is affected by both the problems anticipated in a rotation and specifically the following crop. There are many examples of linked pests or diseases. Avoid choosing green cover crops from the same plant family.