In India, over 500 million tons (Mt) of agricultural residues are produced every year (MNRE, 2009; IARI, 2012). With increased production of rice and wheat, residue production has also increased substantially. Cereal crops (rice, wheat, maize, millets) contribute 70% of the total CRs (352 Mt) comprising 34% by rice and 22% by wheat crops. The Rice-Wheat (RW) system accounts for nearly one-fourth of the total CRs produced in India. The surplus CRs in some regions are typically burned on-farm. The amount of surplus CRs available in surplus states is estimated between 84 and 141 Mt year–1 where cereals crops contribute 58%. Of the 82 Mt of surplus CRs nearly 70 MTs (44.5 Mt rice straws and 24.5 Mt wheat straws) are burned annually (Y Singh et al., 2014). Burning of rice straw is common in north-western parts of India causing nutrient losses, and serious air quality problems affecting human health and safety.
Burning of CRs causes severe pollution of land and water on local as well as regional and global scales. It is estimated that burning of paddy straw results in annual nutrient losses of 3.85 million tonnes of organic carbon, 59,000 t of nitrogen, 20,000 t of phosphorus and 34,000 t of potassium at the aggregate. (P Kumar et al., 2015)
CRs burning results in the emission of smoke which if added to the gases present in the air like methane, nitrogen oxide and ammonia, can cause severe atmospheric pollution. These gaseous emissions can result in health risk, aggravating asthma, chronic bronchitis and decreased lung function. Burning of crop residue also contributes indirectly to the increased ozone pollution. It has adverse consequences on the quality of soil. When the crop residue is burnt the existing minerals present in the soil get destroyed which adversely hampers the cultivation of the next crop.
A study by P Kumar et al. (2015) estimates that total annual welfare loss in terms of health damages due to air pollution caused by the burning of CRs in rural Punjab amounts to Rs. 76 millions. These estimates could be much higher if expenses on averting activities, productivity loss due to illness, monetary value of discomfort and utility could also be considered. There is additional monetary cost of burning to the farmers in terms of additional fertilizer, pesticides and irrigation. One also needs to add the losses of soil nutrient, vegetation, bio-diversity and accidents caused because of low visibility. The gravity of the situation demands that an appropriate policy should be evolved to promote alternative uses of CRs to prevent their on-farm burning.
Alternative Uses of CRs
The CRs produced during the harvesting of rice and wheat crops can be used for various alternative uses if it is not burnt. These include use of crop stubble as fodder for animals, use of crop stubble for the generation of electricity, use as input in the paper/pulp industry etc.
In some countries crop residues are used as a source of energy, animal feed, composting mushroom cultivation or even burned in field. In China 37% of crop residues are directly combusted by farmers, 23% used for forage, 21% discarded or directly burnt in the field, 15% lost during collection, 4% for industry materials and 0.5% for biogas (Liu et al., 2008). Thus burning of crop residues in the field is a major problem in China as well.
Study conducted by P Kumar et al. (2015) in Patiala district of Punjab reveals that an average, total amount of stubble generated for paddy and wheat per acre was around 23 and 19 quintals, respectively. Out of this in the case of paddy, more than 85 % was burnt in the open field and less than 10 % was incorporated, while rest of 8 % was used for other purposes. In the case of wheat, 77 % of the total amount was used as fodder for animals while 9 % was incorporated and around 11 % was burnt.
Most Suitable Alternative Uses of CRs in India
Fodder for Animal in Fodder Deficit Regions of India
The availability of crop residue in India is 253.26 million tonnes whereas the requirement is 415.83 million tones. Thus there is shortfall of almost 40 %. On the other hand, the availability of green fodder during the same time period is 142.82 million tonnes and requirement is 221.63 million tonnes with a short fall of almost 36 % (P Kumar et al. 2015).
A fodder marketing study by ILRI (2010) revels that fodder in Bihar is traded over long distances. Intra-state trade takes place between surplus and deficit zones, which are far apart. Inter-state trade takes place in the form of export to Jharkhand in the north, West Bengal, especially Kolkata, in the south and import from Uttar Pradesh into some part of northwest Bihar.
Because of bulkiness, transportation is inconvenient and costly. The survey results of ILRI shows that on average transport cost alone accounts for 36% of the final price, other marketing costs account for another 32%. Therefore, technological and financial interventions to ease transportation and reduce transport cost will be beneficial. With Public-Private-Producers interventions, the pellets of residues after mixing other required ingredients could be transported from surplus areas to deficit regions. The regional Governments in deficit zones can also create buffer stock and develop fodder banks. More or less every year some regions of India faces environmental calamities like flood, drought etc. and farmer faces acute shortage of fodder.
Establish Bio Thermal Power Plants
Another suitable use of CRs which is being encouraged by various institutions and departments is for generation of electricity. A 10 MW biomass based power plant at village Jalkheri, Fatehgarh Sahib with paddy straw as fuel was set up in the year 1992 and operational since 2001(P Kumar et al. 2015). This kind of initiative should be promoted in the region with the help of Public-Private entrepreneurship interventions.
Paper and Pulp Board Production
The paddy straw is also being used in conjunction with wheat straw in 40:60 ratios for paper production. The sludge can be subjected to bio-methanization for energy production. The technology is already operational in some paper mills, which are meeting 60 % of their energy requirement through this method. Paddy straw is also used as an ideal raw material for paper and pulp board manufacturing. As per information provided by PAU, more than 50 % pulp board mills are using paddy straw as their raw material (P Kumar et al., 2015).
Mushroom Cultivation
CRs can be used for the cultivation of Mushroom. One kg of paddy straw can yield up to 600 g of mushrooms. At present, about 20,000 metric tonnes of straw is being used for cultivation of mushrooms in Punjab (P Kumar et al., 2015).Through Public-Private-Partnership (PPP) women, small and landless farmers could be encouraged to produce more Mushroom which can enhance income and nutrition security.
Straw Mulching
The incorporation of the straw in the soil has a favorable effect on the soil’s physical, chemical and biological properties such as pH, Organic carbon, water holding capacity and bulk density of the soil. Many international and national organizations are working in these regions (Punjab and Haryana) like as Borlog Institute for South Asia, CIMMYT, PAU, HAU, ICAR etc to promote Conservation Agriculture (CA) which advocates for residue retention and mulching. The concept of CA encompasses three management objectives: eliminating or significantly reducing soil tillage to minimize soil disturbance, retaining crop residues on the soil surface, and encouraging economically viable crop rotations that best complement reduced tillage and crop residue retention (Wall, 2007).
Cost of Alternate Uses
The alternative use of CRs for animals or for the generation of electricity and other uses require various on-farm and off-farm operations, including collection, packing, handling, transportation, storage and pre feeding processing. For collection of straw after combining, imported conventional field bailers are available. According to Owen and Jayasuriya (1989) the bulky nature of the straw makes them expensive to transport even for short distances. According to a study by Gupta et al. (2004), the bailing cost is around Rs. 800 ha−1 . The total cost of operation, including bailing, collection, transportation up to a 5-km distance and stacking is Rs. 1,300 ha−1 or Rs. 650 t−1 of straw. However, the problem with these bailers is that they recover only 25–30 % of the potential straw yield after combining, depending upon the height of plant harvested by combines.
Conclusion
Considering the negative impact of CRs burning in India especially in north western states, following measures are strongly recommended;
= Economic analysis of alternative uses; deep understanding through research on economics and trade-off of alternative use of CRs.
= Innovation Platform for awareness; development of a well designed, consistently implemented stakeholder outreach, education, and communication programs that address local, state, regional and national issues pertaining non-burning alternative program implementation.
= Public - Private – Partnership (PPP) to promote alternative uses; would provide better platform to engage all stakeholders - policy makers, researcher, extension agents, government as well as donor agencies
= Promote Mushroom cultivation; especially encourage women, small and landless farmers which can enhance income and nutrition security.
= Promote Conservation Agriculture; encourage farmers to adopt CA techniques, zero-tillage, residue retention, use of happy seeder etc.