Abstract
Biochar, i.e. charred organic material, appears to increase nutrient retention in soil. The mechanism for how this happens is not clear. Here two possible mechanisms, adsorption and microbial immobilisation, are suggested and compared. It is also suggested that we use biochar in wastewater treatment, and so potentially integrate it better into the total waste management cycle.
Highlights
Increase in population and relative wealth has led to a greater demand for food
Whilst some of the short term effects observed upon biochar application may be explained by pH changes [18], or direct release of nutrients and other substances from the biochar itself [19], the longer-term effects are almost certainly explained by its porous structure and large internal surface area, in a similar way as activated carbon that has been used as an adsorbent for water purification for a long time [20]
Biochar has so far mainly been promoted as a soil amendment, but as a good adsorbent, it may hold promise in low cost wastewater treatment
Summary
Increase in population and relative wealth has led to a greater demand for food. Population growth is estimated to continue at a slowing rate until about 2100 and peak at about 10.1 billion [1]. Many waste products, including sewage and animal waste are rich in nutrients and should be used as fertilizers in agriculture to close the nitrogen cycle as much as possible. This would reduce pollution and reduce the need to use energy intensive mineral fertilizers. Biochar is usually defined as charred organic material used as a soil amendment [7] [8]. To be able to give meaningful advice to farmers and other practitioners on whether to apply biochar and what type of biochar to use, a mechanistic understanding of how biochar works and interacts with other soil factors is necessary
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