Untangling GM

David Morris (Letters, 9 September) claims that no-till farming has limited “green benefits” and quotes Professor David Powlson of the Rothamsted Research Station as the source for this. Prof Powlson’s contention is with scientists in the United Nations environment programme, and is solely about the actual quantities of carbon stored in no-till soils, although the differences are minor.

The total “green” benefits of no-till, as well as soil carbon storage, also include halving nitrous oxide emission (a greenhouse gas 300 times as potent as CO2; agricultural soils are a major if not the primary source), great improvements in soil quality, water retention and drainage.

There is better soil stability, large reductions in machinery use and thus fossil fuel emissions, and enormous increases in soil biodiversity and in farmland bird populations.

The uncertainty that some feel about genetically modified crops is not based on meaningful evidence but on agitation by environmental groups. It is surely the function of government to educate the public, not to pander to unwarranted fears.

Professor Tony Trewavas FRS FRSE

Scientific Alliance 
Scotland

Edinburgh