How do you express affection and care for your soil? There are myriads of love languages of soil but the one that stands out among them is mulching. Mulching refers to the process of topping the surface of the soil with various materials such as straw, compost, leaves, grasses, crop residues, plastic sheets, etc. The word mulch is believed to have evolved from the German word ‘molsch’, which implies soft or decaying. Its name is appropriate given that natural mulches are made to serve this purpose in fields, gardens and lawns. Although the earliest recorded instance of mulching as an agricultural practice dates back to somewhere about 500 BC, it is only recently that we have realized the sustainable and environmental benefits of mulching which comprise the conservation of water, promotion of soil microorganisms, suppression of weeds, enhancement of soil productivity, etc.
Perks of Mulching
Mulching offers numerous benefits to soil, water and ecology some of which are mentioned below:
- Mulching reduces evaporation from and retains moisture in the soil, therefore, it can be conveniently used as a water conservation technique for farming in dry areas.
- Mulch acts as a shield for soil from wind and water erosion preventing the soil from being washed or blown away.
- Mulching upholds healthy soil structure by opening pores and avoiding crust formation which further improves infiltration of water from rain or irrigation.
- In absence of light reaching the soil surface with an adequate mulch layer, weeds struggle to penetrate through it thereby suppressing weed growth.
- Organic mulch material is a great source of food for soil organisms and offers an ideal atmosphere for their growth, development and reproduction thereby improving soil health.
- Crops receive nutrients from organic mulches as they constantly release nutrients to the soil during the process of decomposition.
- Mulching reduces soil heat by protecting it from excessive sun and retaining moisture in summer and protects soil from the excessive cold by increasing warmth in winter.
- Mulching prevents the splashing of soil onto leaves or other plant parts, lowering the risks of bacterial and fungal infestation in plants.
Constraints of Mulching
Although mulching provides various advantages, it may create some issues that can be solved with a little more effort and attention:
- A layer of mulch that is too thick can bury and smother plants, preventing water and oxygen from reaching the roots. Two to three inches of mulch is sufficient.
- Soil microorganisms may use soil nitrogen to decompose carbon-rich materials such as straw, fresh sawdust and wood chips, etc., when they are applied as mulches, hence nitrogen fertilizers such as soybean meal, cottonseed meal, alfalfa can be mixed with mulch.
- Pests such as slugs and snails love to creep through mulch close to plant stems. Wood ashes or diatomaceous earth can be spread around the base of plants to deter slugs and snails.
- If mulch is piled up all around the trunks of shrubs and trees, it can cause the bark to rot. Therefore, mulch should be kept 6 to 12 inches away from woody plant bases.
- Plant material mulches infected with pathogens and pests can transmit the infection to the growing plant, so, only healthy materials should be used for mulching.
Types of Mulch
Mulches are chiefly classified into two categories namely organic mulches which comprise compost, straw, crop residues, leaves, etc., and non-organic mulches which comprise plastic sheets, stone, etc.
Organic Mulches
- Compost/Manure: Well-decomposed compost is one of the finest mulching materials. It boosts the number of microorganisms in the soil, enhances its health, and adds certain nutrients. Since compost has a tendency to be slightly acidic, alkaline soil benefits greatly from its addition. However, it has little power to inhibit weeds as it is exceedingly fine and rich in nutrients.
Green (nitrogen-rich) organic mulches
- Grass clipping: Grass clippings can be used immediately from the lawn mower and make excellent mulches. When freshly integrated into the soil, they provide some nitrogen to the soil. Furthermore, they contribute some organic matter to the soil. However, If the layer is too thick, it may prevent air from reaching the bottom and result in rotting material that is odorous.
- Crop residue: Crop residues should be chopped before they are applied as mulches. Therefore, these should be used sparingly and are advised for locations that frequently experience drought. These materials are also vulnerable to micro-fauna, making them ideal for medium-duration crops. Naturally, nitrogen-fixing plants have a higher nitrogen content than other plants, so slicing and distributing these among other plants can be a fantastic way to replace nitrogen in the system.
Brown (carbon-rich) organic mulches
- Dry leaves: Fall leaves can act as a natural mulch under trees and bushes, exactly like they do on a forest floor. They decompose over time to produce fertile humus and restore fertility, giving the nutrients back to the system. By keeping plants warm over the winter, leaves help to protect dormant plants and aid in the initiation of germination.
- Straw: Similar to other carbon-rich materials, straw can improve the soil as it breaks down. But when it is spread out as a mulch, it is especially useful for holding moisture in the summer and protecting shallow roots from the cold in the winter. It lessens evaporation by reducing absorbed energy by the soil as well as its mobility above the soil. It is also helpful because it works well to lift fruits off the ground. Because of this, it is frequently used as a mulch around strawberries and cucurbits.
- Wood chips/ Bark clippings: These are wonderful mulch materials because they are durable and provide optimal soil aeration. They are useful in both dry and rainy climates because wood bark absorbs excess rainwater and prevents waterlogging conditions. The wood chips release the water they have been retaining when it rains too little, giving plants access to water even during dry periods. Hardwood bark clippings are more nutrient-dense than softwood ones, although they are less widely accessible and some bark products may be phytotoxic.
- Sawdust: Sawdust that has partially decomposed is a valuable mulch material that endures for a long period. It takes time to break down because of the high C:N ratio and nutritional status. It must properly decompose into brown soil before being utilized as mulch. Softwood sawdust decomposes more slowly than hardwoods. Nitrogen can be added externally to sawdust and applied two inches deep to the soil to hasten decomposition.
- Pine needles: Utilizing the needles that huge pine trees and other conifers drop on your land can be a wise decision. This mulch, which is also known as pine straw, can be helpful in some situations. When pine needles are integrated into the soil, the soil becomes more acidic, but only very gradually and gently. When a layer is put as mulch, this is typically not a problem because the material becomes less acidifying as it decomposes.
Living mulches
- Ground covers and green manure: A living mulch can be used to cover bare soil in the winter, during voids in a crop rotation plan, or as ground cover in between plants. In addition to offering the same advantages as other mulches, they can also draw pollinators or other helpful species while they are actively growing. As with any other companion planting, it’s crucial to take the neighbors’ needs and traits into account. The competition for water and nutrients may rise with living mulches, but if the appropriate choices are made, the advantages may outweigh the drawbacks thereby enhancing overall yield. Some examples of living mulches are alfalfa, berseem, sweet clover, vetch, mint, etc.