A climate wake up call - how farmers can build resilience against weather extremes
Dr Sarah Kendall, farmer and ADAS Associate Managing Director of Sustainable Agricultural Systems, considers some of the short, medium and long-term measures farmers can consider to build resilience and mitigate against weather extremes in NFU British Farmer and Grower magazine.
Summer 2022 with its record-breaking temperatures and poor rainfall delivered desperately dry conditions to much of the UK. Meteorologists suggest the weather extremes experienced last summer – and the unusually warm autumn and cold winter that followed – are likely to be the new norm. This past year was the climate change wake-up call no-one should have needed.
The agricultural sector has encouraging research and development projects to arm farmers with the knowledge they need. ADAS is the founder of the Yield Enhancement Network, an initiative crucial to help farmers build resilience, with data collected from 300 UK farmers highlighting the importance of capturing and converting water efficiently and illustrating water limitations on the yields of a range of crops. We know that summer rainfall is insufficient to support the season’s rapid growth period and that we need to look further to understand the water-holding capacity of the soil, and how easily crop roots can access it.
Resilience-building strategies begin with an evaluation of the soil texture and health. Added consistently over five to 10 years – depending on soil conditions – an investment in improving organic matter (OM) is essential to help farmers navigate the peaks and troughs of climate change through improved water retention and drainage.
Soil organic matter
As one of the longer-term strategies, soil organic matter (SOM) improvement presents the following considerations:
- The scope for improvement will depend on:
- the soil type: clays store more SOM
- land use: grass stores more than arable systems due to permanent vegetative cover and lack of disturbance
- rainfall: typically there is more SOM in wetter regions where breakdown is slower
- initial SOM content: how far off is SOM from the equilibrium value for that soil type and land use.
- The rate of increase is slow: typically an initial ‘rapid’ increase over a 20-year period followed by a gentler increase taking anything up to 100 years to reach a new equilibrium level.
- Different organic materials do behave differently – e.g. a compost tends to have more stable carbon that sticks around compared to a farmyard manure (FYM). However, improving soil health does depend on that carbon being used by the soil biology, so although compost will increase soil organic matter levels more quickly than FYM, the FYM will have a more rapid impact on soil biology, nutrient cycling, aggregation etc.
- In terms of water-holding capacity – Droughty low organic matter soils (i.e. sands), saw better crop yields with higher SOM contents – particularly with spring crops.
Root depth
As farmers evaluate the soil texture and develop a plan, inadequate root depth is another key issue. A study led by ADAS crop physiologist Charlotte White highlighted the inadequacy of rooting to depth in commercial modern winter wheat and oilseed rape crops compared to rooting data obtained from the ‘70s and ‘80s, leading to estimated reductions in yield of up to 3.5t/ha in winter wheat and 1.2t/ha in oilseed rape.
The Roots 2 Resilience project will see ADAS identify and test a range of ideotypes in crops common to rotational systems to define genotypes and phenotypes that are suited to cope with water stress.
Longer term, breeders will be able to offer varieties to better withstand weather extremes.
On some farms, implications for the risk of drought on spring cereals has driven a move away from crops such as spring barley and spring wheat. Shifting to a winter-sown rotation has cost implications because more fertiliser is used to meet a higher crop demand.
Understanding the health of soils and optimising cropping processes will provide the foundations we need to combat changing environmental conditions.
More information
This article was first published in NFU British Farmer and Grower magazine, 16 March 2023.
Read part 2: A climate wake up call: Actions to better manage water resources
Read part 3: A climate wake up call – Making farming fit for the future