Plastic mulching for vegetable production

Dr Laishram Kanta Singh, Mrs K Lily Rangnamei, Dr S Roma Devi *

It has become essential for us to produce more and of higher quality produce in order to compete in the global market due to the rising demand for horticulture products and people’s increased awareness of their health. In addition to adopting high yielding varieties and sound agricultural methods, it is necessary to use environmental and biological energy to increase productivity.

Utilizing natural resources wisely and economically with low-cost technologies is flexible. Mulch has recently emerged as one of the most efficient technologies for improving crop quality and yield while also lowering production costs because it is a natural resource. The German word “molsch,” which means soft and beginning to decay, is likely the source of the English word “mulch,” which is thought to be a reference to gardeners.

Mulching is the method or practise of covering the soil/ground in order to improve plant growth, development, and crop production efficiency. The precise definition of mulch is “coating of soil.” While organic mulches like compost, leaf, straw and dead leaves have been utilised for generations, the methods and advantages of mulching have changed over the past 60 years with the introduction of synthetic materials.

The available research and field data on the effects of synthetic mulches has created a substantial quantity of useful information. Comparatively speaking to other mulches, plastic mulches are entirely impermeable to water; as a result, they restrict water losses and soil erosion over the surface and prevent direct evaporation of moisture from the soil. It contributes positively to water conservation in this way.

A prepared seedbed is covered with synthetic mulches, such as landscape fabric or black polyethylene film (the most popular type of plastic mulch), right before a vegetable crop is transplanted or seeded through holes or slits cut into the mulch. Under the mulch, in-row drip irrigation systems irrigate the crop while also dispensing liquid fertilisers.

Mechanization enables the farmer to mulch and plant a multi-acre field in a single day using tools like tractor-drawn bed shapers, mulch layers, and planters. Infrared-transmitting (IRT) mulch, black plastic, and other opaque materials successfully prevent weed development while promoting soil warming and early crop emergence. Alleys between mulched beds typically require cultivation or other weed control measures, and weeds that emerge via planting holes may need to be manually removed.

Advantages of plastic mulching

o It is completely impermeable to water.
o It prevents the direct evaporation of moisture from the soil and thus limits the water losses and conserves moisture.
o By evaporation suppression, it prevents the rise of water containing salts.
o Mulch can make applying fertiliser easier and lessen the amount of plant nutrients that are lost through leaching.
o Mulches can also act as a defence against soil diseases.
o Annual weeds’ germination is prevented by opaque mulches.
o Certain insects will be repelled by reflective mulch.
o Mulches maintain a warm temperature throughout the night, allowing seeds to sprout quickly and young plants to swiftly form a robust root system.
o Mulches made of synthetic materials are crucial to the solarization of soil.
o Due to the increased degree of microbial activity, mulches create a microclimate beneath the surface that is higher in carbon dioxide.
o Under mulch, the soil structure is maintained during cropping period.
o Early germination almost 2-3 days.
o Better nodulation in crops like Groundnut.
o Less nematodes population.
o Water erosion is completely averted since soil is completely covered form bearing action of rain drops.
o When compared to organic mulches, it serves for a longer period.

Types of plastic materials

Several distinct plastic films made of various polymer kinds have all been examined for mulching at various points throughout the 1960s. Although there were some slight variances in their technical performance, LDPE, HDPE, and flexible PVC have all been employed. Polyethylene is preferred because of its higher permeability to long wave radiation, which can raise the temperature around plants at night. Because it is more practical to utilise, the vast majority of plastic mulch produced now is made of LLDPE.

Importance parameters of the plastic film

With the exception of when it is used for solorization, the film’s thickness often has no impact on the mulching effect. However, several recent references do show how crop output is impacted by film thickness. Since it is sold by weight, it is desirable to choose a film that is as thin as possible, but proper consideration should also be given to the film’s durability.

Early mulch films had a thickness of 60–75 microns (240–300 gauge), however with to advancements in film extrusion technology, it is now possible to produce 15 micron thick films. These films are weak mechanically, as evidenced by how easily they tear when tension is applied.

Precautions for Plastic Mulch Laying

o The film shouldn’t be stretched too tightly. It ought to be flexible enough to withstand the conditions of expansion and contraction brought on by changes in solar temperature and the effects of cultural operations.
o Black film should have more slack since this colour exhibits the greatest expansion and contraction phenomena.
o The film shouldn’t be laid on during the hottest part of the day since then it will be expanded.


Selection of mulch

The ecological conditions, primary mulching factors, and secondary mulching factors all influence the choice of mulch.
o Rainy season - Perforated mulch
o Orchard and plantation - Thicker mulch
o Soil solarisation - Thin transparent film
o Weed control through solarisation - Transparent film
o Weed control in cropped land - Black film
o Sandy soil - Black film
o Saline water use - Black film
o Summer cropped land - White film
o Insect repellent - Silver colour film
o Early germination - Thinner film

Methods of mulching

o The mulching area should ideally match the plant’s canopy in size.
o Mulch film is trimmed to the necessary size from the main roll.
o Remove any debris from the area, such as weeds, stones, and pebbles.
o Before mulching, thoroughly till the soil and sprinkle a small amount of water on it.
o To make it easier for the mulch film to be anchored, a small trench could be dug around the perimeter of the mulching area.
o The end of the film should be buried in the ground and should cover the entire area around the tree.
o To allow for water passage, four semi-circular holes could be drilled into the film.
o The opening or slit should be situated parallel to the wind’s direction.
o Use to cover the film’s corners
o To hold the film in place, surround the corners with 4-6 inches of soil on all sides.
o In order to mulch hard soil, dig four 1-by-1-by-2-inch trenches and fill them with gravel or stones.
o Cover the trenches with mulch film, and semi-circular perforations in the film allow water to pass through the mulch and into the trenches.

Mulching techniques for Vegetables/close space crop

o A very thin layer of protection is use on vegetable crops with a short growing season.
o Round holes are made in the centre of the film using a punch, a pipe with a wider diameter, a hammer, or a heated pipe end.
o The mulch film is spread out along the planting row’s length, with one end (along the width) secured in the ground.
o Thoroughly till the soil and add the necessary amount of FYM and fertiliser before mulching.
o The soil is then covered with a layer of mulch film (4-6") to keep it stable.
o The drilled holes in the mulch film are used to directly plant seeds.
o Seedlings for transplanted crops could be inserted right into the hole.
o The hole-punching procedure is the same for mulching established seedlings.

The mulch film is then unrolled over the saplings after being buried at one end along its width. The saplings are held in the hand and inserted into the perforations on the mulch film from the bottom side so that it might spread to the topside during the unrolling process.

Irrigation practices under mulching

o The lateral pipelines used in drip irrigation are installed beneath the mulch film.
o If inter-cultivation is necessary, it is preferable to leave the laterals and drippers on top of the mulch film and control the water flow using a small pipe or through the holes drilled in the mulch film.

Plant growth and yield

The following examples show how plastic mulching significantly affects the production of several vegetable crops:

Conclusions

In light of the evolving technology landscape, plasticculture is essential to Indian agriculture in order to increase crop yields and production. Agricultural water management has undergone a revolution since linear low density polyethylene (LLDPE) as a mulch film was introduced.

Actually, it is advantageous to dryland farmers. This is one of the plasticultural applications that is expanding the quickest.

LLDPE film costs less than a third as much as LDPE mulch film. Additionally, thinner layers (15 to 20 microns) are ideal for mulching activities. However, the price of films has increased because to the rising cost of raw ingredients.

Hence, the government needs to do everything it can to mass produce the film and sell it to the farmers for a fair price. Banks may also provide subsidies to entice farmers to embrace soil mulching.