Green manure is a great, inexpensive way to add organic material and to improve soil.
Green manure is generally planted in the fall, and then incorporated into the soil in the spring. In addition to adding organic material to the soil, these cover crops also help prevent erosion and loss of topsoil.
Legume crops such as hairy vetch can supply 50 to 100 percent of all the nitrogen needed for tomatoes. And, they help reduce the need for synthetic fertilizers.
Green manure crops, when grown for a full season, have been known to break up hardpan (caliche), and improve the air and water conductivity of the soil.
The general practice is to incorporate green manure crops two to three weeks before you plant vegetables. You could also take the temperature of the soil and incorporate the cover crop when the top four inches of soil reaches 50 degrees F. Don’t allow the cover crops to go to seed, though, because the seeds will germinate and cause problems later.
There are several ways to incorporate green manure crops. One way is to till the plants in with a tiller. Another way is to simply hoe them down, and then shovel or rake them into the soil. A third way is to “double dig,” that is, use a shovel to dig the area, turning the cover crops onto the bottom as you dig.
