This comment is from Ron Krupp, author of “The Woodchuck’s Guide to Gardening”, “The Woodchuck Returns to Gardening” and his upcoming book “The Woodchuck’s Guide to Ornamentals & Landscape Plants”.
When I give garden lectures, I am asked, among other things, how to fill the soil. My standard answer is to make compost, grow catch crops, and use green manure, which I will address in this and my next comment.
As soon as my first harvest of lettuce and spinach and other greens is harvested in early summer, I plant annual buckwheat. At the beginning of July and August I plant annual rye, field peas, kohlrabi and oats. In autumn I plant winter rye and legumes in October – both perennial plants.
Catch crops are Grasses, pulses and other herbaceous plants (not grasses) that are planted for protection against erosion; Improvement of soil structure, moisture and nutrient content; Increasing useful soil biota; Suppressing weeds; Providing habitat for beneficial predatory insects; Relief from plant pollinators; Providing wildlife habitat; and providing feed for farm animals.
In addition, catch crops can save energy by adding nitrogen to the soil and providing more soil nutrients, thereby reducing the need for fertilizers. Catch crops promote beneficial insect populations and often minimize or eliminate the need for other insect control measures.
Green manure or live mulch improve soil conditions and provide nutrients for subsequent crops instead of using chemical fertilizers that can damage soil microorganisms.
Compost and catch crops are the ideal way to improve soil fertility in your garden. The difference between green manure and cover crop is that cover crops are the actual plants, while green manure occurs when the green plants are plowed into the ground.
Catch crops and green manure are important for building soil fertility. A cover crop is simply a large number of plants, usually specific annual, biennial, or perennial grasses and / or legumes that grow and cover the soil surface.
Catch crops also attract beneficial insects to the garden, reducing the need for chemical pesticides. Green manure offers similar benefits.
The Magic Carpet Mix from Fedco Seeds in Maine includes a diverse catch crop of 11 different varieties, mainly clover but also vetch, radish, chicory and alfalfa, millet and annual rye. You can use it as a ground cover under peas and runner beans. Cut the crop to 6 inches high; I use my grass shears. Otherwise it goes up to 3 or 4 feet !. These catch crop seeds are inexpensive to buy at gardening and farm centers and in catalogs like Fedco of Maine.
When preparing new beds for perennials, flowering shrubs and trees, home gardeners can plant catch crops. I understand that some gardeners don’t have room for catch crops, but if you’re preparing a new area or removing some flower beds due to invasions, it can be a good idea to add catch crops, especially if you’re removing parts of your lawn. Often times, gardeners have open spaces that fill with weeds. This, too, is a good reason to grow catch crops.
Farmers use green manure more than gardeners; However, the latter have just as much to gain from these crops, albeit to a lesser extent. Why only import fertility with compost when soil fertility can be supplemented by green manure: In autumn I sprinkle animal and plant fertilizer compost over catch crops. Go here.