New Delhi: The government is likely to make purchase of bio-fertilizer compulsory for every bag of urea a farmer buys to promote organic nutrients and slash the use of chemical fertilizers. A task force constituted for promoting balanced and sustainable use of chemical fertilisers has suggested bundling bio-fertiliser with urea bags. It has also asked government to promote drip-fertigation technique in which fertiliser is incorporated within the irrigation water by the drip system. It conserves 30-40% nutrients and cut down water use by 50%.