After one of the most difficult summers British farming has faced for water, rain is finally returning. For many farmers it cannot come soon enough, but after months of drought there is another part of the water story that we need to think about: what happens to that rain when it reaches the ground?
England and Wales had their driest July on record stretching back to 1836, with southern England recording its driest month ever. Some places went almost two months without measurable rainfall, including Wisley in Surrey, which recorded 62 consecutive dry days between June and August.
Although rain has now returned to much of the country, the water problem is far from over. At the beginning of September, 10 Environment Agency areas remained in drought and national reservoir storage had fallen to 56.9%, nearly 20% below where it would normally be at this time of year. Twelve reservoirs or reservoir groups were less than half full, while temporary use bans still covered around 30 million people.
We cannot control when it rains, but we can influence what happens to some of that water when it lands.
This summer we have been working with AerWorx on an on-farm grassland trial that has given us some interesting early results. The findings suggest that improving the physical structure of soil alongside adding biology could help grassland take in more rainfall and maintain productivity through dry conditions. This is particularly crucial as we move from drought towards what could be a wetter and stormier autumn.
From drought to potentially heavy rain
The UK has experienced an extraordinary swing in weather over recent years and 2026 has been another example. England had its warmest spring on record, while soils across much of the country were already drier than expected by the end of May. By late August, 71% of England was classed as being in drought.
The next phase could look very different. El Niño is now firmly established in the tropical Pacific and the World Meteorological Organization says there is a near 100% chance that it will continue through to February 2027. El Niño does not determine Britain’s weather on its own, but the Met Office says its growing influence increases the chance of wetter and stormier weather across north-west Europe, including the UK, during autumn and early winter.
After months of worrying about too little rain, farmers could soon be dealing with periods when a lot of water arrives at once. Rain falling on a field is only useful if the soil can absorb it. If soil is compacted and water cannot move easily through its pore spaces, more of that rainfall remains on the surface or run off the land. This increases the risk of waterlogging, erosion and flooding while losing water that could otherwise have moved down into the soil. With our reservoirs depleted and another growing season ahead of us, storing more of the rain where it falls has become increasingly important.
Soil is one of our biggest opportunities for storing water
Healthy soil contains a network of spaces between soil particles and aggregates. These pores allow air and water to move through the soil, creating a great environment for plant roots and soil organisms to maintain its structure.
Compaction changes this and it is a very big issue in the UK. Working soils under the wrong conditions can compress the spaces within the soil and make it harder for water and air to move through it. This is not a small problem, with the Environment Agency estimating that almost 4 million hectares of soil in England and Wales are at risk of compaction, while more than 2 million hectares are at risk of erosion.
A major review of UK soils found that compaction has been linked with reductions in soil porosity of between 10% and 25%. Researchers have also reported reductions in water-holding capacity and, in badly affected soils, very large falls in the rate at which water can move through the soil.
This matters in wet weather because water that cannot enter the soil is more likely to run across its surface. It matters again when the weather becomes dry because less of the rain that fell during wetter periods has made its way into the soil profile. Good soil structure therefore has a role at both ends of our increasingly unpredictable weather.
What happened in our Hampshire trial?
Over the last 12 months, AerWorx has been running an on-farm grassland trial in Hampshire, led by veterinary surgeon Netty Palliser. The trial compared microbz with four other biostimulants and a soil mineral treatment, both with and without AerWorx mechanical aeration.
The trial contained 14 plots, including an untreated control and an AerWorx-only plot, and measured pasture dry matter, soil water infiltration and soil biology at intervals throughout the year. The summer drought provided an unexpected opportunity to see how the different plots responded when water became severely limited. The results are preliminary and come from one farm, so we need further replicated trials before drawing wider conclusions. However, what happened was interesting.
Over the 12-month trial, microbz used on its own produced a 261 kg per hectare greater net gain in standing grass dry matter than the untreated control, equivalent to a 15% improvement. When microbz was combined with AerWorx aeration, the difference increased to 456 kg per hectare, or 26% more than the untreated control, making it the strongest-performing treatment in the trial.
The water results were particularly interesting.
The soil treated with the combination of microbz and AerWorx recorded an 86% improvement in water infiltration compared with its pre-aeration rate at the beginning of the trial. Across all AerWorx-treated plots, infiltration improved by an average of 90%, compared with an average improvement of 15% in plots receiving the soil treatments without AerWorx.
These figures do not mean that microbz caused an 86% improvement in infiltration. Aeration appears to have been the major factor affecting infiltration across the trial. What interests us is what happened when the physical and biological approaches were brought together.
Then the drought arrived
Between June and August, the untreated control lost 460 kg of dry matter per hectare. The plot receiving microbz without aeration lost 230 kg per hectare, which was 50% less dry matter loss than the untreated control. The microbz and AerWorx plot lost just 30 kg per hectare over the same period, equivalent to only 6.5% of the dry matter loss seen in the untreated control.
The plot that combined microbz with aeration had both the highest pasture performance across the year and a large improvement in its ability to take in water. It then maintained substantially more dry matter than the untreated plot through an exceptional drought.
Soil biology and soil structure need each other
This trial has reinforced something we have been learning throughout our work in agriculture: soil biology cannot be separated from the physical environment in which it lives. Microbes need water, air, food and somewhere to live. Roots need access to water and oxygen and enough space to grow through the soil. If soil is severely compacted, simply adding biology cannot remove the physical restriction.
Research supports this whole-system view. Soil microorganisms play important roles in nutrient cycling, soil carbon and the relationships between plants and their environment. Soil microbes are central to nutrient cycling, carbon storage and the resilience of ecosystems, while plant-associated microorganisms can play a significant role in helping plants respond to drought.
The physical side is just as important. UK research has shown that compaction reduces the larger pores that allow water to move into and through soil. Government guidance on natural flood management therefore includes reducing soil compaction among the ways farms can slow runoff and improve the movement of water into soil.
This is why the combination in our trial interests us so much. Aeration opened the physical structure of the soil, while microbz introduced a diverse living microbial culture made from nature in the UK. We now want to understand much more about how those two things interact.
What about organic matter?
Organic matter is another important part of healthy soil because it affects soil structure, biology, nutrient cycling and the way water behaves within the soil. There is a popular claim that every 1% increase in soil organic matter allows soil to store enormous additional quantities of water.
Organic matter interacts with soil structure, aggregation, roots and microbial life, and these in turn affect how water enters, moves through and remains within the soil. A review of nearly 1,000 studies found a close two-way relationship between soil organic carbon and water, with soil carbon affecting soil structure and hydrology while water availability also affects plant growth, microbial activity and the build-up and breakdown of organic matter.
Water storage in soil is therefore about the whole system: soil type, structure, pore space, compaction, roots, organic matter and biology all matter.
The rain we get needs to go into the ground
The events of 2026 have made this much more urgent. The rainfall that is coming is an opportunity. If it hits compacted soil and quickly moves into ditches, streams and rivers, we can move remarkably quickly from drought towards local flooding without rebuilding the water reserves in our land. In late August we had a striking example of exactly this strange situation, when drought still covered 71% of England by land area while heavy rainfall led to more than 40 flood alerts being issued on a single day.
If more of that water can enter healthy, well-structured soil, it has a better chance of remaining within the landscape and being available to roots and soil life rather than immediately leaving the farm. We think the UK needs to start seeing its soils as part of its water infrastructure.
What can farmers do now?
There is no single treatment that will turn compacted or drought-stressed soil into healthy soil, and the right approach will depend on soil type, farming system, weather and the depth and cause of any compaction.
The first step is to look. Dig holes, examine roots and soil structure, identify compacted layers and see how quickly water moves into different areas of the farm. The Defra-funded survey of 300 grassland sites in England and Wales stressed that farmers should assess both the degree and depth of compaction before deciding whether mechanical loosening is appropriate.
Where compaction is present, well-timed mechanical aeration may help restore pore space, but it needs to be used in the right soil conditions and followed by management that reduces the chance of recompaction. Keeping living roots in the soil, avoiding unnecessary traffic when land is vulnerable, managing livestock carefully, protecting organic matter and supporting soil biology can all form part of a longer-term approach.
Our own results suggest there may also be value in combining physical and biological approaches rather than treating them as separate parts of soil management. We need more research to understand this properly, and that is exactly what we intend to do.
Building resilience from the soil up
The most encouraging part of this trial is not simply that one treatment produced more grass. It is the bigger picture of what happened across an exceptionally difficult year.A combination of soil aeration and microbz produced the highest pasture performance in the trial, improved water infiltration by 86% compared with the plot’s pre-aeration measurement and lost only 30 kg of dry matter per hectare during a period when the untreated control lost 460 kg per hectare.
Those results now need to be repeated across different farms, soils and weather conditions. We want to measure soil biology alongside soil structure, water movement, rooting and plant performance so we can begin to understand not simply whether something works, but why.
We cannot make it rain when we need it. We can, however, do more to make use of the rain when it comes.
References
Initial grassland trial findings show benefits of applyinInitial grassland trial findings show benefits of applying biostimulants to soils decompacted with AerWorx
g biostimulants to soils decompacted with AerWorx. Blog.
https://www.aerworx.co.uk/news/aerworx-grassland-trial-25-26
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