For nitrogen fixing: peas, vetch, lentils, faba beans, clover, alfalfa. For disease control: brown mustard greens, oilseed radish, buckwheat. To break up clay: alfalfa & oil seed radish. In BC, a ...

When you have finished harvesting your sweet pea seeds, cut down and compost the plants. If they have been growing in the soil instead of pots, you could use the stems and roots as green manure.