Mulch is important to your tree's health because:
Mulch insulates the soil helping to provide a buffer from heat and cold temperatures.
Mulch retains water helping to keep the roots moist.
Mulch keeps weeds out to help prevent root competition.
Mulch prevents soil compaction.
Mulch reduces lawn mower damage.
This may include moisture and soil conservation, temperature moderation, salinity and weed control etc. Ideally, mulching has a significant effect on earliness, yield and quality of the crop.
Types of mulching materials used may be organic plant residues, insert material like pebble etc. or and synthetic materials like plastics. However, it is important to note that every material has got its merits and demerits.
Why do we bother mulching around trees, shrubs, and perennials? It is often expensive, has to be frequently re-applied, and doesn’t even totally stop weeds. Do we only use it because it looks pretty? While it may look nice, the real purpose behind applying organic mulch is not merely aesthetic, nor is it solely weed prevention. Mulching around plants creates one of the best environments for growing in our urban soils.
Plants require photosynthesis for purposes of food generation. This requires sunlight. For instance, the use of plastic mulch film prevent the weed plant growing below it from accessing the sunlight. This, in turn hampers the growth of the weed, while working as a control measure as well.
Plastic film with its moisture barrier properties does not allow the soil moisture to escape. As such, the water that evaporates from the soil surface under mulch film condenses on the lower surface of the film and falls back as droplets.
Water’s leaching property causes wastage of the dissolved fertilizer. On the other hand, the use of plastic mulch along with drip irrigation allows the dissolved fertilizer not to go deep into the soil. This in turn allows timely and even distribution of nutrients to the plant. This not only ensure healthy plant growth, but also saves on the amount of fertilizer used.
Plastic mulches prevent the ripening of fruits as a result of direct soil contact. This thereby decreases fruit rot as well while keeping the fruit and vegetables clean. This gives quality produce and better marketability.
The plastic mulch covering the soil decreases the crusting effect of rain and sunlight. Furthermore, the reduction in weed quantity means a decreased need for mechanical cultivation. As such, practices such as weed control between beds of plastic can be done using directly applied herbicides as well as through mechanical means. This means that the soil underneath the plastic mulch stays loose and well aerated.
The benefits of mulching: increased organic matter, nutrients, water, and reduced compaction, can be realized using a wide range of materials. All of these materials need to be readily compostable organic (carbon containing) substances. Materials that are often used are wood, straw, evergreen needles, seed hulls (cocoa beans, coconut husks), and compost. Some of these materials, such as straw and wood chips take longer to decompose and consume more nitrogen thereby reducing their benefit. Evergreen needles may acidify the soil which can be troublesome for certain plants. Some seed hulls are toxic to pets and decompose completely in the same season reducing their extended benefit. Compost does little to prevent weeds and sometimes encourages them. Our preferred organic mulch is shredded hardwood.
This product provides benefits up to three years and should be applied 3” deep around the absorbing roots of the plant. When mulch has noticeably thinned, it is time to reapply to continue benefiting the plants.
Ideally soil erosion should be less than 4 to 5 tons per hectare on annual basis. One of the greatest advantages of a plastic mulch is the reduction of water runoff and erosion. This is because the cover, by intercepting raindrops, ensures the protection of the valuable fertile soil.
Mulches can be homes to pests, although combining with other good organic practices should minimize this.
Organic mulches usually need to be applied in the first stages of decomposition. Failure to adhere to this causes loss of nitrogen from the soil. This is in addition to anaerobic decomposition which can lead to ‘sour mulch’ which turns acidic and damages the plants it is supposed to be protecting.
