Introduction
Mulching is the practice of covering the soil to make more favourable conditions for plant growth, development and efficient crop production. The research as well as field data available on effect of synthetic mulches make a vast volume of useful literature. Plastic mulches are impermeable to water; it therefore prevents direct evaporation of moisture from the soil and thus limits the water losses and soil erosion over the surface. The suppression of evaporation also has a supplementary effect; it prevents the rise of water containing salt, which is important in countries with high salt content water resources.
Mulching is mainly employed for moisture conservation in rain fed areas, reduction of irrigation frequency and water saving in irrigated areas, soil temperature moderation in greenhouse cultivation , soil solarization for control of soil borne diseases, reduce the rain impact, prevent soil erosion and maintain soil structure and in places where high value crops only to be cultivated.
Types of mulch film
A wide range of plastic films based on different types of polymers. Owing to its greater permeability to long wave radiation which can increase the temperature around plants during the night times, polyethylene is preferred and also linear low density polyethylene (LLDPE) because it is more economic in use.
Selection of mulch
Selection of mulches depends upon the ecological situations and primary and secondary aspects of mulching: Rainy season - Perforated mulch , Orchard and plantation - Thicker mulch , Soil solarization - Thin transparent film , Weed control through solarization - Transparent film , Weed control in cropped land - Black film , Sandy soil - Black film , Saline water use - Black film, Summer cropped land - White film , Insect repellent - Silver colour film and Early germination - Thinner film.
Methods of mulching
• Mulching area should preferably be equivalent to the canopy of the plant.
• Required size of mulch film is cut from the main roll.
• Clean the required area by removing the stones, pebbles, weeds etc.
• Till the soil well and apply a little quantity of water before mulching
• Small trench could be made around the periphery of the mulching area to facilitate anchoring of the mulch film.
• Cover the film to the entire area around the tree and the end should be buried in the ground.
• Semi circular holes could be made at four corners of the film in order to facilitate water movement.
• The position of the slit/opening should be parallel to the wind direction7
• Cover the corners of the film with 4-6 inches of soil on all sides to keep the film in position.
• In hard soil, make a trench of 1’x1’x2’ depth on four corners of the mulching area and fill it up with gravel or stones, cover the trenches with the mulch film and allow the water to pass through the mulch to the trenches via semi circular holes on the film.
• The mulch material should be punctured at the required distances as per crop spacing and laid on the bed. The seeds/seedlings should be sown/transplanted in the holes.
Irrigation practices under mulching
• In drip irrigation the lateral pipelines are laid under the mulch film
• In case of inter-cultivation, it is better to keep the laterals and drippers on top of the mulch film and regulate the flow of water through a small pipe or through the holes made on the mulch film.
Plasticulture is crucial to Indian agriculture in view of the changing technological scenario for boosting crop yields and productivity. Introduction of LLDPE as a mulch film has brought a revolution in agricultural water management and it is actually a boon to farmers.
