Mulching is the process of introducing vegetative material to the surface of soil in fields to provide soil cover, reduce evaporation, maintaining an even soil temperature and ultimately improve organic content in soil. These materials can include grasses, crop residues, tree bark and other plant materials, even including seaweed if it is available. These materials should be well decomposed, and mixed well into the top soil when the growing season is over. Mulching improves soil fertility by creating a positive soil environment favouring microbial activity and other promoting beneficial organisms such as earthworms, increases moisture retention, stabilises soil temperatures (protecting soils from both heat and cold), reduces soil erosion and restricts weeds. The temperature control keeps roots and plant bulbs cool in the summer and warm in the winter. It can be utilised on all scales of farm, depending upon the availability of input mulch materials. It is considered a climate smart approach as it sequesters carbon in the soil and promotes soil health which in turn maintains agricultural productivity and the ability of a farmer to adapt to climate changes. In some cases, shredded plastic is sometimes used as a synthetic soil cover, but this is not considered climate smart, as it does not integrate organic matter to the soil, instead introducing plastics.
To effectively undertake mulching the following should be carried out. Tools required: shovel, scissors or shears.
- Step 1: Gather organic materials from the farm and other external sources if possible. grasses, crop residues, wood chips, tree backs and other plant materials.
- Step 2: Prepare a location to stock-pile mulch material. A large farm will need a substantial area or pit to achieve this. For smaller operations, mulch can be stored in open-topped barrels and bags punctured for air holes. Storage must allow moisture to contribute to the decomposition process, but no become waterlogged.
- Step 3: Chop/shred organic material and add to the stock-pile. With larger amounts of material, a motorised, or pedal driven chopper/shredder is useful.
- Step 4: Allow materials to decompose, but do not leave for extended periods as nutrients and minerals will be lost.
- Step 5: At the end of the growing season, remove any remaining weeds from the soil surface.
- Step 6: Spread mulch material over the surface approximately two centimetres deep.
- Step 7: In firmer or more compacted top soils, lightly work the mulch into the upper soil.
- Step 8: Lightly water area where mulch has been applied.
Mulch should be applied annually as mulching materials will decompose.
- FAO 2019. Soil cover. Sustainable Agriculture Platform. Rome, Italy.
- Hosbeg N.D. Advantages and disadvantages of mulch. Hosbeg website.
- Farmer’s Weekly 2014. Mulching: what is it and how to do it properly. Farmer’s Weekly website. South Africa.
- CCAFS 2019. Climate Smart Agriculture 101. CSA Portal. Wageningen, The Netherlands.
Benefits
- Mulching improves soil structure, fertility and quality, stabilising soil temperature and retaining moisture.
- Mulching can increase nutrient content in the soil.
- Mulch can contribute to reducing soil erosion.
- Mulching contributes to preventing weeds from growing.
- If not used, mulch can be sold to other farmers.
Drawbacks
- Despite positive benefits, requires substantial labour inputs, hence the need for on-farm labour resources, or the ability to hire.
- Mulch can spoil if not managed correctly.
- Considerable quantities of mulch are needed to cover fields.
- Again, if not managed correctly, can harbour pests, diseases and weeds (seeds).
- If over-applied, can result in a toxic environment.
