Carbon, soil and a potential new revenue line

Soil holds carbon, and farming practice determines whether it gains or loses it. Ukrainian chernozem holds a great deal, and decades of intensive cultivation have reduced it. Reversing that is agronomically valuable in its own right, and it may also become saleable.

The practices involved

Reduced or zero tillage, which stops the oxidation that ploughing accelerates. Cover crops between main crops, which put root carbon into the soil. Longer rotations. Retention of crop residue rather than burning.

All of these have an independent agronomic case: better water retention, less erosion, lower fuel use. That matters, because a practice that only pays if the carbon market pays is a fragile business.

The measurement problem

Selling a carbon credit requires proving that carbon is present, that it was added by the practice, and that it stays. Soil carbon is variable across a single field, changes slowly, and is expensive to sample properly.

Modelled estimates are cheaper but less trusted by buyers. That tension is the reason soil carbon markets have developed more slowly than markets for, say, avoided emissions.

The additionality question

A credit should only be paid for carbon that would not have been stored anyway. A farm that had already moved to no-till for its own reasons has a weak claim, and buyers know it.

A cautious conclusion

Adopt the practices for the agronomy. If a credible market emerges, the revenue is a bonus on top of a change that was already worth making. Building a business plan the other way round is a mistake.

What cannot be measured cannot be sold — as true of any industrial product as it is of carbon. In soil carbon the problem is not the practice but that measurement is expensive and additionality hard to prove. Caution is right; but once measurement becomes cheap this could turn into a second revenue line from the same hectare.