Omesh Thakur
College of Agriculture & Research Station
Fingeshwar, Gariaband IGKV, Chhattisgarh

Introduction
Mulching is the process or practice of covering the soil/ground to make more favourable conditions for plant growth, development and efficient crop production. Mulch technical term means ‘covering of soil’. Mulching is an agricultural and horticultural technique in which the use of organic materials (plant residues-straw, hay, groundnut hulls, leaf and compost, peat, wood products-saw dust and animal manures), and synthetic materials (paper, polyethylene, wax coated papers, aluminium, steel foils and asphalt spray emulsions etc.) with or without shallow tillage, for the purpose of increasing soil productivity is involved. This technique is very useful in protecting the roots of the plants from heat, cold or drought or to keep fruit clean. It checks evaporation and modifies the soil and air microclimate in which a plant is growing. Mulch is used to cover soil surface around the plants to create congenial condition for the growth. This may include temperature moderation, salinity and weed control. It exerts decisive effects on earliness, yield and quality of the crop. The research has proved that mulches are fruitful and productive in the production of horticultural crops.

Mulch
Any material used (spread) at surface or vertically in soil to assist soil and water conservation and soil productivity is called mulch. The word mulch has been probably derived from the German word “molsch” means soft to decay, which apparently referred to the use of straw and leaves by gardeners as a spread over the ground as mulch .Mulching as an application of layer of covering material on the soil surface.

Advatages of plastic mulch
  • Prevents weed growth and acts as barrier to soil pathogens.
  • Accelerates uptake of micro nutrients from the soil by the active root zone.
  • Enhances quality of the produce with cleaner crop.
  • It is completely impermeable to water.
  • It prevents the direct evaporation of moisture from the soil and thus limits the water losses and conserves moisture.
  • Mulches maintain a warm temperature even during nighttime which enables seeds to germinate quickly and for young plants to rapidly establish a strong root growth system.
  • Synthetic mulches play a major role in soil solarisation process.
  • Mulches develop a microclimatic underside of the sheet, which is higher in carbon di-oxide due to the higher level of microbial activity.
  • Water erosion is completely averted since soil is completely covered form bearing action of rain drops.

Types of mulches: 
Mulches are either organic or inorganic.

(a) Organic mulches are those derived from plant and animal materials. Those most frequently used include plant residues such as straw, hay, peanut hulls, leaf mold and compost, wood products such as sawdust, wood chips and shavings and animal manures. Organic mulch properly utilized can perform all the benefits of any mulch with the possible exception of early season soil warming. However, natural mulch materials are often not available in adequate quantities for commercial operations or must be transported to the place of use.

(b) Inorganic mulches those mulches in which plastic film are used called as inorganic mulch. They are available in various like black, Red, Yellow, Silver, White, Transparent etc. They have distinct optical characteristics and thus reflect different radiation patterns into the canopy of a crop, thereby affecting plant growth and development. This light reflectivity can affect not only crop growth but also insect response to the plants grown on the mulch. Yellow, red, and blue mulches increased green peach aphid populations, and the yellow mulch, which attracted increased numbers of striped and spotted cucumber beetles and Colorado potato beetles. Yellow has long been used in greenhouses to monitor the population of insects. Mulches with a printed silver surface color have been shown to repel certain aphid species and reduce or delay the incidence of aphid-borne viruses in summer squash. Similar to a white mulch, the degree of opacity of a gray mulch may require a herbicide or fumigant to be used to prevent weed growth. Plastic mulches directly impact the microclimate around the plant by modifying the radiation budget (absorbitivity vs. reflectivity) of the surface and decreasing the soil water loss. The color of a mulch largely determines its energy-radiating behavior and its influence on the microclimate around a vegetable plant. Color affects the surface temperature of the mulch and the underlying soil temperature.

Mulching techniques for Vegetables /close space crop :
  • Very thin film is used for short duration crops like vegetables.
  • Required length of film for one row of crop is taken and folded in ‘thaan’ form at every one metre along the length of the film.
  • Round holes are made at the center of the film using a punch or a bigger diameter pipe and a hammer or a heated pipe end could be used.
  • One end of the mulch film (along width) is anchored in the soil and the film is unrolled along the length of the row of planting.
  • Till the soil well and apply the required quantity of FYM and fertilizer before mulching.
  • Mulch film is then inserted into the soil on all sides to keep it intact
  • Seeds are sown directly through the holes made on the mulch film.
  • In case of transplanted crops, the seedlings could be planted directly into the hole.
  • For mulching established seedlings, the process of punching the hole is the same. One end of the film along the width is buried in the soil and the mulch film is then unrolled over the saplings.

Application of black polythene in vegetable crops:

1. Potato
  • Mulching hastened and improve sprouting, plant growth and yield in early crop.
  • Reduce seed tuber rotting.

2. Cucurbits, tomato, brinjal, chilli
  • Organic mulches improve the yield.
  • Improves the quality of vegetables by avoiding the direct contact with soil.

3. Onion, Tomato
  • Effectively stops the weed growth.

4. Plastic mulches
  • Transparent/ black control the disease like Verticillium, Rhizoctina etc.
  • Transparent polyethylene mulch reduced whitefly populations, aphids caught in yellow traps and virus diseases incidence.

Conclusion
Generally, using mulch can be an effective method to improve water productivity and preserve water resources. Black PVC film shows better control on weed growth and also increase the yield and maintain the microclimate of the crops.

References:

Jacks C V, Brind W D, Smith R.1955. Mulching Technology Comm., No. 49, Common Wealth. Bulletin of Soil Science. Pp.118.

Schalk J. M., Creigaton C. S., Fery R. L., Sitterly W. R., Dewis R. W., McFadden T. L., Augustine D. A. Y. 1979. Reflective film mulches influences insect control and yield in vegetables. Journal American Society of Horticultural Science 104, 759-762.