Climate change is widely spread and recognized as serious threat to human society and natural ecosystems. Emission of various gases, anthropogenic activities are responsible for climate change. Loss of soil carbon might be attributed to climate change. However many scientist suggested four other mechanisms that may be responsible for reduction in soil carbon and they might be due to less application of organic manure in soils, deep ploughing, and removal of stubbles from fields and intensive farming. Biochar acts as soil conditioner that improves carbon sequestration in soil and reduces carbon emission from soils.
The term “Biochar” defined as black carbon formed by pyrolysis of biomass (plant material) in oxygen limited conditions and seems to be an analogue of traditional charcoal. Biochar is broader term grasping all kind of black carbon produced from any feedstock material. Form and size of feed stock and rate of pyrolysis determine quality and effectiveness of biochar. Carbon content in biochar is inversely proportional to biochar yield but directly proportional to time pyrolysis. Naturally occurring biochar in our soil is due to wildfire and is deemed to be a diverse soil carbon pool.
Biochar works in two ways:
(1) Carbon sequestration: In carbon sequestration, biochar act as soil additive that store carbon in soil otherwise that carbon might be lost in atmosphere in form of CO2. The extent of carbon sequestration depends on long lived and resistance to chemical processes like oxidation.
(2) Biofuel and biomass energy production: During pyrolysis of feed stock for biochar production, energy or fuel is produced as bio product which is environment friendly.
Several studies revealed that there is no negative impact reported so far arising from applying biochar in soils. Their use as a source of energy could offsets carbon emissions arising from combustion of fossil fuels.
Its application in agriculture:
Soils with low bulk density and/or higher organic matter lessen the fuel requirement for mechanical tillage. Soils with high organic matter have high water holding capacity and nutrient retention capacity. Biochar helps to add more organic matter in soil and ultimately reduces cost of production per unit area and more per unit area yield might be achieved with reduced irrigations. This is very helpful in rain fed area where only source of irrigation is rain. Pakistan soils have organic matter 0.5-0.8% but satisfactory level is 2%. Furthermore, our farmers are deprived of importance of stubble incorporation, which is excellent source for organic matter in soil. But farmers feel reluctant to incorporate stubbles in order to save money and time. However, biochar is very attractive in that context, simply broadcast or incorporate it in soil. Surprisingly, little information has been gathered on the application and impact of biochar on soil and plant from economic point of view.
Carbon sequestration is main driver of considering biochar application to soil. Incorporation of biologically derived organic matter into a highly stabilized form can reduce CO2 emission from soil. Along with carbon storage in soil, biochar also enhances soil fertility, crop yield, soil moisture retention, and nutrient retention and use efficiency. Theoretically, biochar has been worked using three kind of mechanisms (I.) direct amendment of soil chemistry through its inherent elemental and compositional make up, (II.) Modification in soil nutrient dynamics by giving chemically active surfaces (III.) Manipulating physical nature of the top soil in such a way that improves proliferation of roots and nutrient and water retention and acquisition
Through worldwide, markets of biochar are not accessible, and are ill-developed. Although “Biochar” concept is old but its adoption is ignored due to various political, economic factors. A model farm on which biochar is practiced so as to motivate farmers to buy and get benefit from it does not exist yet. In general, there also remains a lack of acquaintance and awareness of bio-energy and carbon markets.
RESEARCH PRIORITIES AND FUTURE CHALLENGES
Based on the importance and potential of biochar, the following research priorities have been identified:
1) Determination of a prognostic relationship for potential properties and its composition such that it can be optimized for use in soil.
2) Examination and quantification of contribution of biochar to reduce adverse impacts of various gas emissions on the soil and atmosphere.
3) Estimation of the impacts of alternate bio-energy systems on the carbon cycle at the global scale, and calibration of different models to support policy decisions and devise suitable market gadgets.
Biochar is farmer friendly organic compound. Both public and private sector should be fostered to develop its industry so that to increase chances and opportunities for fresh graduates.
Mohsin Tanveer, Habib Ullah, Dr. Shakeel Ahmad Anjum. (Associated with Agro-biology lab, Department of Agronomy, University of Agriculture Faisalabad.)