Brewing climate friendly tea in the garden

Recently, when I was attending my local community seed swop in rural Lewes in East Sussex, in England, I came across an allegedly environmentally friendly version of charcoal called biochar, which the industry mouthpieces are promoting as an alleged way of keeping carbon in the soil reducing greenhouse gas emissions, while at the same time improving soil fertility and thus the productivity of crops. Really?

It is fairly well known that you can use charcoal to heat your house or to cook your food. Biochar, however, is a type of coal that is created when you burn biomass and the biochar industry is promoting biochar as an alleged way of keeping carbon in the soil and thus reducing greenhouse gas emissions from the soil, while at the same time improving soil fertility and thus the productivity of crops. This concept is currently being sold to unsuspecting farming communities around the world, but it could be a complete waste of money as the actual benefit of biochar is yet to be proven.

In Lewes, the biochar industry lobby was a the seed swap, where it was trying to bring on board unsuspecting but keen allotment holders to the biochar cause, by telling them how biochar can be used to make the local soil more fertile, though the degree to which results offer long term carbon sequestration in practice has been challenged. 

The industry wants to launch biochar commercially in rural communities around the world; the seed swap in Lewes provides the industry with the right test audience. The seed swap features among other things practical advice on saving seed, good fruit tree health, willow weaving, and thanks to the industry, this year also using special biochar stoves for tea-making. 

In principle, adding a stable form of organic carbon to farm soils is a good old idea; it could sequester carbon and at the same time increase soil fertility and farm productivity. This is the principle of proven ecological farming practices. Current biochar projects are however mainly small scale and still in development. Despite this, the biochar lobby is already touting this potentially false unproven climate solution, which could prove to waste money that could be better spent on developing more certain ecological practices, like avoiding bare soil, growing legumes and cover crops. So, biochar may not be the right way to go for small farming communities in England or elsewhere in the world. Uncertainties surrounding biochar include how long the carbon would actually be locked in the soil, and how biochar improves soil fertility in the first place as simple chicken manure has been shown to produce higher crop yields than fertilizing with biochar.

The biochar lobby may well be using local community-based events, like the seed swap in Lewes, to build grassroots support for their business, but their optimistic claims need to be balanced with information about the uncertainty of their solution and the corporate interests in getting biochar and soil carbon included into carbon markets.

Testing biochar in my own allotment may tell me something about its use in improving soil fertility and yields, but testing for soil organic carbon is not something that can be done in the back garden and will probably not prove to be any allotment owner’s cup up tea!

In the context of chemical fertilisers, biochar may be seen as a 'false' solution to climate change mitigation in agriculture and an obstacle for a real move towards ecological soil fertility without chemical fertilisers and without green washing.