IMPLICATIONS OF CLIMATE CHANGE

  • Written by Andrew Davis
  • Posted on Aug 04, 2022
  • Articles

The recent record temperature and the prospect of a drought being declared set me thinking of the practical implication of climate change for farmers.  The first six months of this year have been the driest since 1976 with February the only month when rainfall was above average.

I vividly remember 1976.  The previous Michaelmas, I had taken on the tenancy of Cannon Heath Farm, an extra 1,000 acres on the south side of Watership Down.  Full of enthusiasm and with a large bank loan, the harvest of 1976 was disappointing, to put it mildly.  Harvest was over by the end of July and most crops achieved little more than half the budgeted yield.  At least the cost of harvest was low and the drier was redundant!  The planned investment into a breeding ewe flock had to be scaled back significantly.

It was not as hot as this year, but the warm sunny days continued for more than two months, unlike this year when, the brief heatwave apart, there have been cooler cloudy days too, just no rain!  As I write this, combines are cutting winter wheat and oilseed rape, even winter beans.  Reports of winter barley were reasonably good but it is too soon to get much idea of the rest of harvest.  Those who have given an indication of winter wheat suggest that it has held up remarkably well with little damage to yield or quality caused by drought.  That may be because there was some rain at the end of May, a critical time.

What impact will climate change have on arable crops over the coming years?  In theory, a higher level of carbon dioxide in the atmosphere may boost yields but only if there are no other limiting factors.  Milder damp winters should extend the growing season, vital if harvest is to come earlier.  It may not matter if crops ripen in late June and early July if there was more growth in winter and spring, although day length plays its part too in crop development.

There have been new crops grown over the past fifty years or, at least, a larger area, and this will surely continue, whilst geographic range moves northwards.  Oilseed rape was brought in by the Romans, it is thought, and there are certainly records of it being grown in the 14th century.  But it was almost unknown on British farms until the mid-1970s when it suddenly became very popular.  Very large areas were grown until neonicotinoid insecticides were banned after several years of restrictions, and decimation by flea beetle attack persuaded many farmers to give up growing the crop.  The area is increasing again as agronomists learn how to combat flea beetle attack without using insecticides.

Rapeseed is one of the most widely used cooking oils, another being sunflower oil.  The area where sunflowers are grown has moved north through France, could we be growing them here?  Planted at the end of April, they should be ripe to harvest by the end of September.  One report suggested that late frost could take a toll but another said that they are relatively frost tolerant.  Certainly, soil temperature needs to be above 6°C when the seed is planted so a cold spring might be a problem.  They need relatively little fertiliser but are somewhat susceptible to disease, particularly sclerotina.  Yields of 5 tonnes per hectare have been achieved in France and Germany.

Whilst speaking at the AGM of the Berkshire CPRE recently, I was asked why we import soya from Brazil, encouraging farmers to destroy the rain forest.  In 2019, some 3.5 million tonnes of soya beans, either whole beans or oil and meal, were imported, 65% from South America.  75% is used in livestock rations but there is also a growing market for human consumption.  When soya is crushed, the result is 20% oil and 80% cake or meal which is fed to animals.  With its combination of amino acids, it is high quality protein, unmatched by the peas or beans that are currently produced here.  So could we grow soya in the UK?

A report published in 2017 claimed that 5,000 ha were grown that year with the prospect of 10,000 ha the following year.  So it would appear to be becoming more widespread, although I have not heard of any farmer growing the crop.  As a legume, it could be a valuable restorative option, providing high quality oil and protein whilst reducing imports.  Like sunflowers, it is sown in late April and harvested in late September or October.  As most soya grown in South America is GM, the beans grown here might command a premium.

Maize is another crop that was rarely seen on British farms until the 1970s but is now grown widely, ensiled for animal fodder, as feedstock for anaerobic digestion plants or even a little for grain.  Perhaps the biggest success has been vines with a huge increase in the area and range in recent years.  Our sparkling wines have even competed successfully with champagne!  These trends will surely continue.

The problem for grazing livestock is the lack of grass growth in a summer drought.  It is ironic that ruminants may be able to graze through the winter but may need supplementary fodder in mid-summer!  Lucerne and sainfoin, both legumes and drought resistant, may be more widely grown.

The combination of climate change and the skill of plant breeders may well result in a broader range of crops grown in the UK, especially when gene editing becomes more widely used to speed up the development of new varieties.  One risk is that climate change may also bring new pests and diseases to threaten crop production.  But farming is remarkably resilient and there will be opportunities to exploit.