Plastic mulch drastically reduces production costs

Small-holder farmers can cut costs of irrigation and mechanisation by adopting synthetic mulch.

Ministry of Agriculture Extension officer Samuel Mburu says just like traditional organic mulch, which controlled weeds and retained moisture content in soils, this method boosts harvests while reducing labour required in production process.

With depletion of vegetation, agro-companies have developed synthetic mulching materials from plastics for small and large-scale farmers with open fields or greenhouses.

Although polythene mulch complements drip irrigation especially on large-scale, Mburu says, it is equally appropriate for small-scale farmers like those with kitchen gardens.

“We have no more grass, weeds and other organic materials to cover soil to prevent water loss. Farmers want to bring more land under irrigation, but losing the water to evaporation will lead to high production costs. An investor would like to use little to earn more. Synthetic mulch comes in handy,” he says,” he says.

This practice is common with short season crops such as tomatoes, cabbage, kale, sunflowers, maize, cucumbers, among others.

With climate change, the extension officer says, farmers in high rainfall areas are likely to suffer losses when it fails to fall due to altered patterns.

Weed suffocation

The mulch smothers unwanted plants in the shamba.

“Weeding does affect the quality of the harvest. A farmer will also spend in mechanical weeding or using herbicides. Digging disturbs soil structure. At the same time, resides from herbicides reduces 'quality' of the produce, making it hard to pass export tests for instance to European markets,” he said.

The special polyethylene mulch covers soils around the stem of crops. Other spaces between the lines may remain exposed.

Nutrients

But the covered areas will have a continuous layer of moisture, which will be a medium of flow of mineral nutrients in form of ions.

Excessive rain at times cause loss of nutrients through leeching, yet they are important for a healthy crop.

But a polythene sheet will drain excess water away from the crop, allowing for a balanced concentration of of nutrients.

“Soils temperature, especially warmth, is fairly maintained under this micro-environment,” the Machakos County-based extension officer says.

He, however, says organic mulch is the best because it rots with time, adding more nutrients to the soil unlike the polyethylene sheet.

The decomposition also increases soil particles' binding ability.

Amiran Kenya is one of the horticultural companies using this technology locally.