[Terrapreta] biochar and alkaline soils

[adkarve]

I live in India, in Masharashtra state, that produces 40% of the total sugar in India. We have had sugar factories since the early 1930s. All the sugarcane is manually harvested. Typically, a hectare of sugarcane produces about 10 tonnes of dry leaves, so that after the harvest is over, the field is covered with a layer of dry leaves that is often 30 cm thick. Farmers just burn the leaves to clear the field. The charred leaves and ash are then ploughed into the soil. Farmers do not grow consecutive crops of sugarcane but always rotate it with other crops. About 50 years ago, there were many farmers who harvested more than 200 tonnes of sugarcane per ha and the average of the state in the 1960s was 100 tonnes per ha. But then yield started declining. The average has now come down to about 80 tonnes per ha and one hardly meets a farmer who harvests more than 150 tonnes per ha. The soil in the sugarcane area is vertisol, having a pH ranging from 8.2 to 8.7. I am not saying that incorporation of char and ash caused decline in sugarcane yield. There might be entirely other reasons for it, but after reading that biochar might not work in alkaline soils, one is tempted to come to this conclusion. 

Yours 

A.D.Karve

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