After sowing turmeric around late-May/early-June, Avtar Singh covers his entire field with a 3-4 inch-thick layer of paddy straw. “I do it so that my crop and the soil get proper shade from direct sunlight,” says this farmer from Mullanpur in Mohali district of Punjab, while referring to a practice known as ‘mulching’.
But wouldn’t having such a thick cover hinder germination? “On the contrary, germination is advanced by 10 days when compared to the non-mulched field, while giving me at least 10 per cent more yield,” claims Avtar.
Amarjit Singh of Gharuan village in the same district also does mulching in his sugarcane-garlic intercropped field, using 4-5 tonnes of paddy straw to cover one acre with the help of 5-6 labourers in a day. “Mulching requires extra labour, but it does wonders by improving soil health and saving water. And it needs to be done only once, at the time of sowing,” he notes.
Mulching basically involves application of a protective layer of material to the field soil surface just after sowing any crop. The material could be organic and biodegradable (paddy straw, sugarcane bark, dry grass, trees leaves and even newspaper) or inorganic and non biodegradable such as polythene sheets.
According to GS Butter, Head of Agronomy at Punjab Agricultural University (PAU) in Ludhiana, mulching is very effective for pest management and disease control.
“Weed seedlings cannot survive under the mulch, which also means not having to use chemical weedicides. Besides, mulching reduces evaporation from the soil bed. This not only brings down the frequency of irrigation, but also protects the soil from erosion,” he explains. Surjit Singh, a retired PAU scientist, points out that biodegradable mulches like dry paddy straw contain 50-70 per cent nutrients that slowly decompose in the soil, enhancing its fertility even without using fertilisers. “Mulching creates an ideal environment for earthworms and other beneficial organisms to grow on the soil. We have been recommended mulching for turmeric, potatoes, sugarcane, melons and all types of vegetables,” he adds.
Sadly though, only a few hundred out of Punjab’s 12 lakh-odd farmers practice mulching. A state with the country’s highest average fertilizer and pesticide usage, apart from 75 per cent of its area under the ‘dark zone’ signifying severe groundwater scarcity, ought to be paying more attention to such environment-friendly practices.
Punjab, moreover, produces an estimated 38 million tonnes of straw annually, over half of which is from paddy. While wheat straw is used as cattle feed, there is no such use for paddy straw. About 80 per cent of the latter — some 16 million tonnes — is simply burnt in the fields after harvesting to clear the land for the next sowing. This abundant straw can potentially be used by every farmer for mulching, thereby addressing a major source of air pollution in the state.
“Unfortunately, farmers here want everything the easy way. Rather than putting some extra labour in utilising paddy straw for mulching, they prefer burning it,” observes Surjit Singh.
Amarjit Singh from Char Ke village in Jalandhar says that crops normally require irrigation every second day during the summer months. But with mulching, the watering requirement is only after 7-10 days, depending on the crop. “There are hardly any weeds and pests in my fields and nor is there need really for using chemical fertilisers,” says this farmer, who uses sugarcane bark for mulching in his four-acre field where he grows sugarcane inter-cropped with ‘ma-ki-dal’ (i.e. urad or black gram).
At the Punjab government’s Centre of Excellence for Vegetables in Kartarpur near Jalandhar, set up under an Indo-Israel project, scientists are showcasing vegetable cultivation using polythene sheets for mulching.
“We use 30 micron sheets to cover the entire fields. Even the open space between the bed rows is covered in order to control weeds. The vegetable seedlings are transplanted in the soil through holes in the sheet that are a few inches apart to maintain plant-to-plant distance,” says Daljeet Singh, who heads the Centre.
The sheets, he informs, would cost Rs 12,000-13,000 per acre and can be used in two or more seasons. The polythene mulch enhances crop yields by keeping the soil warm in winters and providing much-needed moisture to the plant in the summer. “We are growing the best-quality tomatoes, brinjal, capsicum, chilly, cucumber, bitter gourd and round gourd under plastic mulch at this centre,” he adds.