with about 400 units spread across the country, the sugar industry occupies a prime place in the Indian economy. The byproducts of the industry are bagasse, filter cake (pressmud) and molasses. Together they constitute about 40 per cent of the total weight of crushed cane. Of this, pressmud ( pm ) accounts for 3-7 per cent.
An estimated 5.6 million tonnes of pm is currently generated in India. Depending upon factors like clarification process, variety of sugarcane and harvesting time, pm is a potential source of soil nutrients, wax and can be used to treat alkaline as well as acidic soils ( Fertiliser News , Vol 44, No 11).
pm is a soft, spongy, lightweight material with a moisture content of 50-60 per cent. It consists of a mixture of sugarcane fibres, sucrose, wax, inorganic salts and soil particles. pm is being used as a source of either nitrogen or phosphorus. Some researchers have studied its potential to improve the status and availability of micronutrients.
In addition to improvement in nutrient availability and crop yields, pm application also favourably influences the physical properties and microbial population in soils.
In India, considerable work has been done on the use of pm as a source of plant nutrients for various crops. In the alkaline soils of Bihar, Gujarat, Maharashtra, Punjab and Uttar Pradesh, the crop yield due to pm application increased considerably. It varied between 15-20 per cent, while in the acidic soils the response has been as high as 150 per cent.
pm is also used to reclaim saline and acidic soils. The effectiveness of gypsum and pm was compared for reclaiming Bihar's saline areas. It was observed that pm was more effective than gypsum as a reclaiming agent.