Agricultural intensification transfer carbon (C) to the atmosphere in the form of carbon dioxide (CO2), thereby reducing ecosystem C pools. Agriculture contributes 10–12% of the total global anthropogenic greenhouse gas emissions.
Diminishing increased levels of CO2 in the atmosphere by pyrolysis to convert biomass into biochar, which stabilizes the carbon (C) that is then applied to soil. Biochar withhigh concentrations of carbon that can be rather recalcitrant to decomposition, it stably sequestercarbon.
The immediate beneficial effects of biochar additions for nutrient availability are largely due to higher potassium, phosphorus, and zinc availability, and to a lesser extent, calcium and copper.
The presence of biochar in the soil can improve soil chemical (e.g. pH, CEC), and physical properties (e.g. soil water retention, hydraulic conductivity). Acting as a habitat and substrate for soil microorganisms, biochar added in the soil can increase microbial activities (Pietikäinen et al., 2000).
Connection between primary biochar properties (outer circle), the soil process they may influence (intermediate circle) and the soil biota (inner circle), white arrows indicate the influence between biochar properties.
Agricultural and horticultural crops have benefit from VAM on a world-wide basis. The potential application of VAM to the agriculturaland horticultural industries is great.
Fungi involved in this symbiotichost root: broad spectrum of VA mycorrhizal fungi(VAMF) to determine the most promising combination for maximum growthresponse for a particular crop.Biochar and mycorrhizae in soil lead to an altered levels of nutrient availability that affects both plants and mycorrhizal fungi, modifies plant mycorrhizal fungi signaling, serves as a refuge from hyphal grazers and protected from soil predators.
Biochar addition to soil increases in root colonization of AMF. Arbuscular mycorrhizal (AM) fungi are symbiotic soil organisms. AM fungi play role in vegetative succession of ecosystem, plant diversification and productivity, as well as restoration and re-establishment of degraded ecosystems. Arbuscular mycorrhizal fungi (AMF) increasesplant nutrition because they
- to increased root absorption,
- carry minerals essential to plant health to the roots
- acts as antibiotic barriers to root pathogens,
- increase the tolerance of plants to extremes in soil temperatures and pH,
- increases the longevity and tolerate stresses like transplant shock, soil compaction,
- soil toxins and heavy metals.
The increase in the availability of major plant nutrients due to application of biochar and mycorrizhae, the plants form mycorrhizal symbioses with specialized soil fungi. A simple term to define this is the buried alliance of plants and fungi and benefits are as follows
- Biochar could alter the signalling dynamics between plants and Mycorrhizal fungi, or detoxifies allelochemicals.
- Plants secrete a number of compounds that can increase root colonisation by Mycorrhiza as well as promoting spore germination and hyphal branching. Some of these compounds are CO2, flavonoids, sesquiterpenes and strigolactones. Addition of biochar can change pH, usually an increase, and this can “switch” these compounds on.
- Biochar c adsorb these signalling compounds, especially high temperature chars.
- Biochar could act as a sink, so reducing mycorrhiza activity.
- Biochar can also adsorb compounds toxic to mycorrhiza.
Root colonization of Biochar and Mycorrizhae
The combination of biochar, mycorrhizal fungi approaches the goal of a viable soil environment for sustainable plant growth. It has often been observed that application of organic biochar amendments results in a higher level of C sequestration when compared to other management strategies including fertilizer application and conservation tillage.
The opportunities for carbon sequestration and the reduction of greenhouse gas emissions have not been explored at all, but they are potentially significant.
Senior Research Fellow, Department of Soil Science and Agricultural chemistry,
Vanavarayar Institute of Agriculture, Manakkadavu, Pollachi - 642 103, Tamil Nadu, India