Switch in land use ‘will see crops fail’

Astudy into the implications for UK agriculture if society shifts towards more plant-based diets has concluded that conversion from livestock to arable production would result in regular crop failures in many places.

The analysis, led by the Rothamsted Research Institute and focused on the south-west of England, found that the chances of successfully growing winter wheat on fields once used to raise livestock could be as little as 28% in future, as increased rainfall will make sowing the crop impossible in some years.

Lead author Dr Lianhai Wu said: “Adapting to the changing climate and changes in consumer demands will force us to diversify land from its current uses.

“Livestock grazing is the main type of farming across the west of the British Isles and it has been suggested that grasslands in the region could be converted to other land uses, such as growing cereal crops.

“However, our simulations suggest that planting winter wheat between October and December would be impossible in some years because of constraints on soil workability.”

On arable land, unsuitable soil conditions during the sowing or harvest periods will decrease yield if sowing or harvest are delayed – or even prevent it entirely.

The study also looked at the implications for soil carbon storage and greenhouse gas emissions if grassland cut three times a year to provide silage was converted to winter wheat.

Including two other greenhouse gases, nitrous oxide and methane, in the calculations, it showed that while the average greenhouse gas emissions from soil growing ryegrass were higher than from the same land converted to wheat, this was compensated for by the greater amounts of carbon stored within the ryegrass.

Grasses return more of this carbon to the soil after they die, and as such, carbon stocks declined annually after converting grassland to wheat by 165280kg of carbon per hectare, depending on climate and soil type.

“Grassland conversion in the region would not be sustainable in terms of carbon sequestration, although applications of livestock manure or other organic materials could mitigate soil C losses to some extent,” said Dr Wu.

“In terms of storing carbon in the soil, converting grassland to winter wheat is therefore unsustainable in areas similar to the south-west of England, such as many other areas in the UK and northern Europe.”

ADAPTABILITY: The changing climate and consumer demands could force farms to diversify their land use.

Converting grazing land to arable is ‘unsustainable’.