Pakistan being an agriculture-based country with a large number of hectares of growing and generating a large number of wastes related to agriculture.
By Muhammad Usama Rasheed, Athar Mahmood, Maria Naqve
The solid waste generated from crop residues constitutes about 82.12 million tons annually with a huge amount of over 365 million tons annually. In recent last decades, the agricultural pollution enhanced many times contributing more towards environmental pollution and hazards such that burning Rice stubbles in huge amounts contribute as a source of smog which is a serious problem for human and animal health. The solution to such types of problems lies in generating new technologies to cope with the waste produced by agriculture i.e., Biochar. As a new emerging clean environment technology biochar not only reduce the agricultural waste problems but also reduce the cost of production of crops by enhancing the soil fertility and reducing use of in-organic fertilizers.
Biochar is a diverse material rich in charcoal like substances and helps to reduce carbon from the atmosphere by adding carbon and minerals nutrients to the soil. The basic concept of biochar is that plant and animal waste contain a large amount of Carbon ranging from 45-60% and Oxygen about 35-40%. The other elements such as hydrogen, nitrogen and minor amounts of minerals. Basically, when biomass burned and detoriated a lot of minerals leached down and carbons diffuses into the air which cause environmental problems that can be addressed using biochar. There are two different methods of preparing biochar i.e., pyrolysis or gasification system.
Pyrolysis is the combustion of biomass in the absence of oxygen resulting in the decomposition of the organic matter with syngas and biochar on the other hand gasification use limited amount of oxygen and high temperature to convert the biomass to biochar but the mostly used technology for producing is the pyrolysis. The biochar is high resistive to decay for 100-1000s of year for wood biochar and act as a continuous supply of nutrients and carbon which acts a potent source. For soils like Pakistan where temperature and low amount of organic matter is present use of biochar can act as an energy booster to the farm. The biochar is prepared by the incomplete digestion of the biomass and which adds carbon in stable form to the soil. In this way removing of carbon from carbon cycle. The biochar alkaline reaction reduces the soil acidity. The application of biochar is increasing day by day due to the prospective of increasing soil nutrient holding capacity and water retention and also store sustainably the carbon and thereby control of greenhouse gases.
This helps in mitigating climate change and converts a huge amount of waste to a useable resource. Biochar reduces soil density and soil hardening, increases soil aeration and cation-exchange capacity, and changes the soil structure and consistency through the changes in physical and chemical properties. It also helps to reclaim degraded soils. It has shown a greater ability to adsorb cations per unit carbon as compared to other soil organic matters because of its greater surface area, negative surface charge, and charge density, thereby offering the possibility of improving yields. Samples with a sufficient amount of stable carbon can be added to the soil to be sequestered to a high adsorption surface of biochar can characterize it as a soil additive, competent of halting risk elements in soil. The controlled amount of burning does not go towards the loss of nutrients rather it is help full to produce a material healthy for soils and microbes. The energy generated in the combustion process is offset substantial for the climate and environment as it is controlled. For instance, if all the Indonesian rice is converted to biochar and incorporated into the soil it will be equal to the whole of Norwegian CO2 emission. During the production of biochar some incomplete products may also formed which includes volatile hydro-carbons that acts as a pollutant to the human and environment.
The constraints related to biochar in Pakistan is related to the use of farm waste as an alternative source of energy for fuel and as a source of low-quality animal feed. The process of making of biochar is quite complicated and the high transport cost makes reluctant to the farmers to adopt such technologies. Despite all the benefits associated with the biochar there is very less or no attention to it as compared to the developed countries which are generating new resources and controlling environmental pollution and climate change. Recently the President announced 10 units of biochar where farmers can sale their crop residues and instead of burning can take money. The Research done on biochar is not conveyed to field levels. All the institutes of the country should gather at a platform to make the things happen. Biochar is a complete package of resources for the developing world as the developed world is moving towards the sustainability and the resource generated high yielding agriculture needs higher inputs on sustainable bases to feed large amount of population. The reduced climatic effect will provide efficient and better health for the farmers and the family in limiting resources. The by-products formed during the combustion helps in generating the environmentally friendly fuels when consumed do not affect the environment and climate that much. Although biochar is a very good technology but farmers are reluctant to do it because of the lag present between research and information.
Authors: Muhammad Usama Rasheed, Athar Mahmood, Maria Naqve Department of Agronomy, University of Agriculture Faisalabad.