Gardening is not just about having a green thumb. While it looks like a fun hobby, behind this aspect of agriculture is a science that should be dealt with care and knowledge. The soil is, of course, an essential component of gardening. And as well as the plant itself, the soil should get special treatment. We’ve heard of fertilizers doing amazing things to improve soil, but there’s another alternative: green manure cover crops.
What is Green Manure?
First of all, no. it’s not the mental picture you just got. It’s not green poo. Green manure comes from cover crops— temporary crops that are planted during or at the end of the growing season to retain the viability of the soil for the next planting. While green (hence the name), they are incorporated into the soil by plowing, thus not only adding to the biomass (organic matter) of the pre-imposed soil but also increasing the nutrients that can be made available for the next generation of crops.
Used by Ancient Greeks and Chinese
Green manure has been used for centuries. Broad bean plants were used by Ancient Greeks while the agriculturally-inclined Chinese used grasses for improvement of farm soil. It’s not such a very modern thing after all. Today, many alternatives can be used, and remember: take into account the season in which these alternatives can be grown. Winter cover crops, or fall or late-summer green manure crops are typically legumes, such as Fava beans, cowpea, alfalfa, Sunn hemp, and soybean. Non-leguminous crops, like wheat, rye, radish, sunflower, Sorghum, Tyfon (a plant of the genus Brassica; a relative of mustard), and also mustard itself.
What are the Uses and Benefits of Green Manure?
Aside from the apparent increase in organic material in the soil, green manure crops improve the soil’s aeration (letting the air seep into it; basically, letting the soil breathe), its water filtration and retention, granulation, and it also protects the soil from water and wind erosion. All are beneficial for the growth of the plant. Green manure contributes a lot to the improvement of the soil, unlike chemical fertilizers, which only refurbish certain nutrients.
Legume crops, from atmospheric nitrogen, can manufacture fertilizing nitrogen. Along with phosphorus and potassium, nitrogen is a macronutrient that is important for the plants that must be consumed in large amounts. Green manure also suppresses the growth of weeds and lessens the need for pesticides and fertilizers.
Green manure also acidifies alkali (basic) soil. A pH that is more than 6.5 to 6.8 disables the plants from absorbing macronutrients. Unlike composting, green manure adds over 40 tons of organic matter per 1 hectare or 2.47105 acres. While composting requires a water supply nearby, rainwater will make do for green manure crops. Moreover, they are used where they planted; compared to compost, which must first be transported onto the plant field.
Don’t Go To Seed
One thing that the gardener must be cautious about is sowing cover crops. The gardener should not let it go to seed, else the cover crop will be invasive, spreading throughout the field and will cause damage to the field. Mind you, you’d have a hard time raking them out.
A Win-Win Deal
Before resorting immediately to fertilizers and other mainstream solutions in the gardening industries, look for alternatives first. Green manure for the field will, of course, also incur expenses; but the benefits that it yields outweigh that of chemical solutions. Besides, the cover crops that come before green manure can also be used for human consumption, so it’s a win-win deal.
Crimson Clover is a wonderful cover crop video( 2:36 min) by covercropdave