Page 25 - ALG Issue 1 2025

COMMUNITY
WILL ‘NO WATER’ BE
THE NEW ‘NO DIG’?
Mains water usage on our allotments is often highest when water availability is lowest – in hot, dry periods. For several years, the RHS has encouraged gardeners to cut down on our use of mains water to irrigate our gardens, through their ‘Mains2Rains’ initiative.This focuses on
4 areas: Slowing the flow of water into drains, creating healthy soils, why roots matter, and collecting the rain. By adopting a few simple practices, we can all make our allotments thrive on the rainfall we receive by collecting it and re-using it during dry spells.
Earlier this year, I attended a presentation, “Measuring ‘Mains2Rain”, at Speedwell Allotments, Bristol.The session was run by Sarah Venn, founder of Edible Bristol, and Janet Manning, water scientist and Water Reduction Officer at the RHS.They are working on a water saving project looking at how cultivation processes will enable them to minimise the use of mains water on the Edible Bristol plot.
With a grant from WaterWise, they had a smart meter installed replacing the standard meter fitted to the site water supply.The meter measures when the water is actually being used, not just the volume used. It immediately picked up that there was a
leak in the system, as it registered water consumption overnight. If your site has a mains supply, I recommend making this change; it could save you a lot of money. The grant also enabled some IBCs to be installed to collect rainwater from the sheds.
The main focus of the scheme is the soil. Healthy, well-conditioned topsoil has approximately 30% water holding capacity. This equates to some 100L in the top 30cm of each square metre of soil, an IBC in every 10 square metres(sqm) and the equivalent of 12 IBCs per half plot (125 sqm).The challenge is holding that water in the soil, not allowing it to disappear as run off, evaporation or draining through the topsoil into the subsoil too quickly, taking valuable soluble nutrients with it.
The mains2rains website offers advice
on how to achieve this and these are the practices Edible Bristol had already adopted, by mulching the no dig beds, planting perennial crops, shading the soil through
closer planting of crops or ground cover crops and adding compost regularly.The dual-purpose paths are covered in chipped wood which, as it breaks down, it is raked up each year and added to the planting beds, paths acting as both walkways and low-level compost heaps! Even the area outside the main hut, regularly walked on, was soft and springy with no evidence of compaction.There is little bare soil on the site. Mulching and crop cover can lower soil temperature in hot weather considerably, reducing both evaporation and stress on the roots of plants.
Early results indicate that Edible Bristol’s plot uses less than half the quantity of water that comparable plots on the site uses and most of that is used to water the polytunnels.The crops planted outside in beds are just well watered in when they are planted out and rarely watered again before harvesting.This encourages them to develop long roots finding deep moisture in the no dig beds.This helps improve soil structure and create resilience in the plants to withstand prolonged dry periods.The rhizosphere, the area round the roots of plants, has the most microbial activity in the soil which helps hold moisture in the soil.
Janet and Sarah talked about how allotment sites and plots can reduce their mains reliance.We all know the wisdom of harvesting rainwater, but do we know how much can be collected from our sheds? A standard 8’x6’ shed has a roof area of about 4.8sqm. For every mm of rainfall, it could collect 4.8L of rainwater, 48L, a quarter of a water-butt, with every 10mm of rainfall.
We discussed the need to integrate allotment water supplies with surrounding drainage systems. Speedwell Allotments surround a fairly new block of flats with a roof area of nearly 500sqm.All the runoff goes into a SUDS (Sustainable Drainage System). If there had been awareness
and collaboration between the housing association, planners and the council, some of this runoff could have been diverted to
storage facilities on the allotment, reducing, or even eliminating the need for mains water on the site.
Janet told us that Ofwat, the water
ser vices regulator, is developing its Water Efficiency fund priorities for the 2025-30 period. Imaginative projects which reduce mains water use could receive some funding. She recommended contacting your local water company for advice on water saving schemes, with the potential for par t funding of projects. It might take some planning and preparatory work but in the long term it could both reduce the mains water use of allotments and help water companies meet some of their sustainability objectives.
In 2019, the ALG magazine published articles by the Brighton and Hove Allotment Federation (‘Water use and sustainable allotmenteering’ issue 3 p42) and Russell Attwood, Deputy Rep East Midlands,
(‘The power of mulch over drought and deluge’ issue 4 p30) which discussed water conservation methods on allotments.There seems to be a growing awareness amongst allotment holders that simply turning on a tap to water our crops is not a sustainable practice in the long term. It is also likely to become increasingly expensive.
We have learnt to appreciate the benefits of working with nature to create good soil structure to help grow our crops and ‘No Dig’ has gone from being a cult to standard practice on allotments. Will ‘No mains water’ be the next ‘No Dig’?
References and further reading... https://www.mains2rains.uk/ https://www.incredibleedible.org.uk/ https://www.waterwise.org.uk/ watersworthsaving.org https://www.gardenorganic.org.uk/ exper t-advice/watering-guide
Finally, best wishes to Sarah, who, shortly after this presentation, was treated for a serious health condition.We wish her well in her ongoing treatment and recovery.
Mark Joynes
“We all know the wisdom of harvesting rainwater, but do we know how much can be collected from our sheds?”
Allotment and Leisure Gardener | Issue 1 2025 | 25