Cover Crops Confer Many Soil Health & Productivity Benefits In gardens & On Farms, Including Nitrogen Fixation, Weed Control, Increased Organic Matter, Increased Yields, Reduced Soil Compaction etc. Read More Below.
The benefits of cover cropping include all the above and much more. Below I briefly mention the cover crop benefits and include a few examples of good practice when it comes to the benefits of cover crops for soil health and improved crop yields.
What Are Cover Crops?
Cover crops are plants that are planted to cover the soil over winter, or at other times, rather than for the purpose of being harvested.
Improved Organic Matter
By growing a cover crop there is huge potential to increase soil organic matter. This is especially true as the seed grows into a larger plant and is then left in, or on, the soil rather than being harvested and removed. This means that all the organic matter that grows returns to the soil. In essence this means we have converted the plant nutrients that were in the soil into organic matter. And that has to be good as it means that nutrients can’t be leached away and are stored as plant material.
As the plant organic matter then decomposes it releases plant nutrients, some of which may have been savaged from deep within the soil, for the next crop. It’s a virtuoso circle of growth.
Carbon Sequestration As a Cover Crop Benefit
Another of the cover crop benefits is that some of the plant material produced will be left in the soil, especially the roots, and the carbon will be sequestered. This locks the carbon in the soil and it can persist, in the right conditions, for millennia.
This is especially true where soil cultivation is reduced. Indeed soil cultivation in intensive systems where ploughing or digging is practised releases soil carbon, whereas No Dig and various forms of regenerative agriculture sequesters carbon.
Improved Rainfall Infiltration & Storage
When rain falls on bare soil it soon runs down hill and, in the conditions erode the soil. the rain doesn’t soak in to the soil as readily and the aquifers don’t fill as quickly.
But where there is a crop cover the leaf cover slows rain down. And the roots open the soil making infiltration more probable. And as soil organic matter increases overt the years infiltration also increases.
This in turn means our soil have improved water storage capacity.
This may sound contrary to the above but as well as water capacity being increased, the drainage also improves. As the plant roots grow downwards its like nature’s way of fracking the root zone. The roots force soil particles apart and this allow water to drain away. And when the roots later decay the channels they formed are left for water to drain through. Provided that is, that we don’t cultivate the soil too heavily. If we do we then go backwards again!
Soil Erosion Prevention
As indicated above a cover crop can prevent erosion caused by rainfall. As the planet warms, and rains become more intense, that has to be a consideration if we are to minimise soil erosion.
Another of the cover crop benefits is weed control. Well grown cover crops can swamp out the weeds by competing for space, light, moisture and nutrients.
Reduced Soil Compaction
With a crop on the ground we are not so likely to damage the soil by driving over it, walking over it and cultivating it when conditions aren’t conducive.
Not only that, but as organic matter builds over time, the soil becomes more tolerant and can cope with minimal disturbance. Its why I am happy to walk on my No Dig beds when they are not sodden. Because they have a lot of organic matter they are much more resilient.
More Cover Crop Benefits Below
Pollinators and Beneficial Insects
Pollinators need plants in flower. Bare soil doesn’t flower but cover crops can. And when they do they can become a haven for pollinators and beneficial insects.
Care should however be taken not to allow crops to seed as we don’t want a second generation of plants coming in the next crop.
The way to prevent this is to cut or otherwise destroy the crop before it produces seed. Small areas can be trimmed or scythed without causing soil compaction.
Where the cover crop is a legume we naturally benefit from nitrogen fixation. And as the cover crop plant roots subsequently decompose in the soil they release that nitrogen to our next crop. That’s a huge cover crop benefit.
In winter field beans or peas are a potential cover crop. In the warmer months think about tares, lucerne or similar. Each has their cover crop benefits.
Cover crops have the benefits that they can become feed crops for livestock or poultry. In a sense this means it is now a fooder crop but I consider that to be nit picking.
If the cover crop can be consumed by chicken, goats, rabbits, sheep etc in situ, so that the manure returns to the soil, then that converts the plant material to plant nutrients without intermediary steps. That has to be a benefit to the soil and the animals. Plus it saves money having to feed wither of them.
Improved Soil Health
All the above improves soil health. And healthy soils mean healthy crops.
Better, healthier, nutrient rich soils means better crops and higher yields. Indeed higher yields is an indicator that cover crops are working to improve the soil.
Many of the above benefits lead to the last one I’m listing. Biodiversity. Cover crops, on farms, or in gardens and allotments, improve biodiversity.
What Species Can Be Used As Cover Crops?
Almost any crop can be used as a cover crop. Faster growing crops, that quickly cover the soil surface are ideal. And I like those with large root systems because they hold the soil together, form deep channels in the soil and sequester more carbon than other species.
Legumes such as vetches and clovers are wonderful cover crops as they add nitrogen. Grasses and cereals such as them oats, wheat and barley also work well as do the brassicas such as kales, mustards, turnips and radishes.
To save money look for large packs and don’t worry about variety too much. Buying from an agricultural merchant (and splitting the packs with friends) will reduce costs.
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