The state agriculture department is promoting the cultivation of green manure these days as Punjab Agro is providing subsidy on the seed at the rate of Rs 2,000 per quintal, which costs Rs 6,300 per quintal without subsidy. The farmers can avail its seed from the block level offices of the agriculture department as limited stock is available with the department and farmers can avail it on first-cum-first-served basis. What are the benefits of green manure for farmers, the soil and crop productivity, ANJU AGNIHOTRI CHABA explains. Excerpts:
Green manures are crops grown specifically for maintaining soil fertility and structure. They are normally incorporated back into the soil, either directly, or after removal and composting. There are three main varieties of green manure, including Dhaincha, Cowpea, Sunhemp. Also some crops such as summer moong, mash pulses and guar act as green manure. Around 11,000 quintals of subsidised seed, which is provided by Punjab Agro, is available with the department. Green manure varieties are incorporated into the soil when the crop is 42-56 days old. Pulses crops are incorporated in soil after plucking of beans after 60 days. Experts said that green manure must be leguminous in nature, bear maximum nodules on its roots to fix large amount of atmospheric nitrogen in the soil. Experts have also said that seeds of green manure should be easily available to the farmers at a low price.
Punjab’s per hectare fertiliser consumption, which is around 244 kg, is one of the highest in the country and is also higher than the national average. Growing green manure can curtail this consumption to a large extent by 25 to 30% and can save huge input cost for the farmers.
Experts said that in Punjab high-intensity agricultural practices are prevalent as farmers take two-three crops in a year, which requires lots of chemical fertilisers such as urea, diammonium phosphate (DAP) etc. And this leads to deficiencies of micronutrients like iron and zinc, especially in the soils where rice is cultivated thus affecting productivity. In such a situation, green manuring helps improve soil health and enhance the productivity of the crops.
Also, even the PH level of the soil in several parts of the state is more than 8.5 and 9 per cent and green manure is beneficial to maintain it at the required level which is 7 per cent.
What is its sowing time?
These can be sown immediately after harvesting the wheat crop. In Punjab, it can be sown from April 15 to the first week of May. Experts said that after wheat harvesting apply rauni irrigation and then pre-soaked seed in water for 8 hours of dhaincha are sown. Around 20 kg dhaincha seed is required per acre. The fields are vacant in the state for 45 to 60 days after wheat harvesting and that is the best period to sow it because these varieties of green manure can be buried in soil when they are 42-56 days old.
For instance, if the farmers go for paddy sowing, which starts from June 10 and continues till early July, then green manure can be incorporated into the soil at the time of puddling, which is needed for transplanting paddy nursery in the field. “Burying 42 to 56 days old dhaincha/cowpea/sunhemp one day before planting paddy will help save 25 kg nitrogen (55 kg urea) per acre. Similarly, burying the residues of summer moong grown as green manure crop after plucking the beans one day before transplanting rice will help save one-third of nitrogen (35 kg urea) per acre. Dhaincha should be preferred in kallar and recently reclaimed soils. In Basmati there is no need to apply nitrogen if 45-55 days old dhaincha or sunhemp or residues of summer mung has been buried in soil just one day before transplanting. To get higher yield of maize, bury 50 days old green manure crop 10 days before sowing maize along with recommended (50 kg nitrogen /acre)dose of nitrogen. It will also help in improving soil health considerably,” said Dr RK Gupta, senior soil chemist, department of Soil Sciences at PAU.
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How does it benefit the soil and crop?
Experts said that it helps in enhancing the organic matter in the soil, meets the deficiency of the micronutrients and reduces the consumption of the inorganic fertilisers etc. “It is a good alternative to the organic manure and it conserves the nutrients, adds nitrogen and stabilises the soil structure,” said Dr RK Gupta, adding that it decomposes rapidly and liberates large quantities of carbon dioxide and weak acids, which act on insoluble soil minerals to release nutrients for plant growth. Also, it contains 15 to 18 quintals of dry matter, which also contains phosphorus, potassium, zinc, copper, iron and manganese, per acre and 20 to 40kg per acre of nitrogen, Dr Gupta said.