The benefits of mulching your vegetable garden are well known, but what is the best contribution to the soil? There are a multitude of possible mulches, but none are really perfect in the sense that they will not fully compensate for the needs of the plants in your vegetable garden. Thus, each mulch has its own nutritional values and provides more or less interesting elements for the soil and the crops.
Like human food, the soil’s food must be diversified to be good and balanced!
Mulching with straw from one year to the next will be flawed, as will the soil mulched from year to year with RCW, which tends to acidify gradually. For a few years now, I’ve been trying to diversify the soil stock in my vegetable garden by doing a kind of “mulch rotation” where I alternate and stack different types of cover each season. This rotation helps to balance the supply of nutrients and nutrients and helps to increase soil fertility and the overall productivity of the vegetable garden.
What does this rotation actually consist of? In this way you can take advantage of the fall of dead leaves from the garden in the autumn to spread them out in the vegetable garden, just like the pruning waste that you will eventually carry out in the autumn. The following spring I gradually apply the previously dried clippings and finally in the summer I add another layer of hay or straw from organic farming to increase the thickness of the cover in anticipation of high summer temperatures so that the soil remains cool and firm in its moisture optimal.
The main organic mulches, their advantages and disadvantages:
-Straw : It is probably the most commonly used ground cover material. As straw provides very good protection of the soil against erosion, it retains moisture and prevents weeds. However, straw is not a very rich mulch and only brings relatively few elements to the soil during decomposition. The potassium content is considerable, but the straw is particularly low in nitrogen and phosphorus.
-The hay : Hay, like straw, has the advantage of being very economical. This technique of mulching with hay, also called “phenoculture”, also has the enormous advantage of being free of phytosanitary treatments, unlike straw which is often treated. Although gardeners are often reluctant to make hay, because of the seeds contained in it, it is not yours, with a rather thick layer (10-15 cm), seeds will not grow without light.
-The BRF : From its real name “fragmented ramial wood”, it is a mulch consisting of small discs less than 5 cm in diameter, obtained by chopping branches, usually from deciduous trees, due to its size. It is an ideal mulch for forest plants, such as blueberries, strawberries, raspberries or even hazelnuts. In the long term, however, this can lead to a harmful acidification of the pH on vegetable growing beds.
– Mowing : Before spreading the grass clippings as mulch, make sure that it is dry first, as disposing of it directly leads to fermentation and a fairly high heat production, which can be dangerous for plants, especially the most sensitive ones. Once in place, the dried chips break down in the soil very quickly (in a few weeks), so it is advisable to add another mulch.
-Dead leaves : They are a favorite mulch in the fall and winter, but their relatively short lifespan does not allow for year-round coverage. At the beginning of spring it will therefore be necessary to compensate with another mulch. However, dead leaves provide significant amounts of humic substances that benefit the soil organisms and improve the soil of the vegetable garden.
-Linen sequins : This product comes from the processing of flax fiber in the form of small flakes, is liquid, easy to process and does not fly away. The beige-white color reflects the sun’s rays and forms an aesthetically beautiful contrast with the foliage of the plants. The pH is neutral and this mulch is quite rich in organic matter. The flax will improve the physical structure of the soil. The downside is that flax does not add many nutrients to the soil.
– Hemp flakes: It is an interesting product because the cultivation of hemp requires almost no phytosanitary products or fertilizers. The hydrogen potential (pH) is neutral. It also has a strong ability to absorb rainwater, which can be both an advantage and a disadvantage. It can lead to plant root rot if the rains are frequent and frequent. It is better to use hemp mulch at the foot of plantations that are especially fond of wet soil. It is less easy to find than other mulches and the purchase price is relatively high.
– Cocoa pods: They have some pretty interesting agronomic characteristics with a pH around 5.7. They can therefore be used on any type of bed, border or in the vegetable garden. In addition, their chocolate color mainly accentuates the plants. Their only drawback is a slightly too high cost price due to the import obligation, which is ultimately not very ecological!
-Pine bark: They are widely used in beds and often neglected because they acidify the soil. However, large calibers decay slowly and can last up to 10 years. Also this form of mulching, very decorative, can be recommended for acidophilic plants, but not between your vegetable plants. You can also place it at the base of your small fruit trees such as raspberries, blueberries or even at the base of shrubs such as service currant.
-Wood chips: Made from recycled wood, it is more of a “decorative mulch” than a true nourishing mulch. We find them in all colors to the most kitsch, from raw wood color, to blue or red, turning into green or yellow. Other than decorating, covering the soil and protecting it from soil erosion, wood chips add little or no nutrients to the soil.
-Miscanthus crushed : It is a grass grown mainly for its biomass for heating. Unlike other mulches, it has a perfectly neutral pH. In addition, this mulch is stable against wind and run-off water and thus prevents erosion. It has a high water retention capacity thanks to its composition (hollow and spongy stem). From an ecological point of view, miscanthus is grown without (or very little) water, without fertilizers and without pesticides (because it has no pests). This high-quality mulching is unfortunately still rare and expensive, as the agricultural sector in France is still in its infancy.
There are also mineral mulches (slate, pebbles, gravel, sand, etc.) or even artificial materials (tarpaulin, black horticultural plastic, felt, etc.). However, I voluntarily ignore them, since these materials are inert and have the common point of bringing nothing to the soil, they are therefore not interesting in the context of a vegetable garden in which we want to sustainably regenerate the fertility of the soil and promote its biological activity.