Magha Shukla Purnima is celebrated as Agira purnima, popularly known and referred to as Agni Utsav (in the panjikas too). Mostly a harvest ritual, it is celebrated by farmers in Orissa by burning a fire in the evening, similar to the Lohri festival of North India.
Cleaning and purifying of homes and the surrounding areas begins a week before purnima. Sticks and straw (kuta) are collected by each household to make the bonfire or agni. In the evening, all the villagers gather around the fire and after a ritual puja and offerings of khechudi, kanika and pitha, the fire is lit. Then the villagers dance around the agni singing songs seeking blessings for a good harvest.
The belief is that the burning of this fire or agni at the time of harvest enhances the fertility and productivity of earth. Another belief is that the direction of the flame foretells the fortunes of the harvest – a westward flame foretells floods, an eastward slant indicates brackish water and high tides, while a north-eastern slant is indicative of a bountiful crop.
Scientifically, down the ages fire has been burnt on lands before harvest as it helps to kill weeds, shrubs and micro-organisms that hamper the growth of crops. It also helps to dry out the excessive moisture that has seeped into the soil in the cold winter. Yet again a beautiful inter-weaving of science and custom by our sages and seers.