Interviews

As the Environment Agency further downgrades its irrigation prospects for the remaining summer, a leading horticultural specialist gives his advice on water resources resilience strategies for the glasshouse sector.

John Adlam founded Dove Associates in 1985. https://www.dovebugs.co.uk/doveassociates.htm It provides managerial and technical services, including water resources management to the nursery industry. He is a past President of the IPPS (International Plant Propagating Society) as well as a Chartered Horticulturist, a Fellow of the Institute of Horticulture and registered Pesticide Practitioner.

John highlights the importance of water recycling as a useful water resilience option to mitigate drought impacts and provide longer term water security. “The biggest thing I’m working on these days is recycling of nursery water. People are capturing rainwater and their own irrigation runoff, processing it, cleaning it, and putting it back. You have to look at ways in which you can preserve the water you have.” It is especially important where growers are unable to increase their licensed abstraction quantities. “The idea is very much to recycle whatever and wherever you can.“

Another recycling option is capturing condensation. John says “Part of the water that you can collect is condensation from the inside the glass house. In the UK it tends to go to waste, but I’m looking at ways we can utilise that. If you have a hot day and a cold night you have an enormous amount of condensation forming on the glass or polythene. As the dew point changes the water forms a film on the underside of the glass.”

A further strategy for saving water is reducing plant transpiration “For crops transpiration (evaporation of water from the plant) is our biggest water enemy, as much as 90% of the water absorbed by a plant can be evaporated from the leaves. It disperses all the water we do get into the air and we do have tools to reduce that. Growers are using antitranspirants (chemicals capable of reducing transpiration). When plants are newly potted or planted in the field they are sprayed with a weak solution of a biodegradable film over the leaf and that dramatically reduces them transpiring. It just naturally cracks and flakes off within 2-3 weeks as the leaf grows. The leaf surface is sealed rather than the stomata being totally blocked up.” John adds “These are all things we’ve always had and known but never really adopted to any degree – but now needs must.”

With the continuing dry weather there are reports that some horticulture businesses are running out of water, especially if supplementing stocks through rainwater harvesting. Some are resorting to tankering in supplies. John emphasises the importance of ensuring appropriate water quality when considering this option. “The water may have a different hardness to your supply as well as differing mineral content. In some cases with quality issues, it may require reverse osmosis treatment as it isn’t sourced from the mains. Young and small plants such as plugs or cuttings won’t tolerate poor quality water and will simply rot and die. We have one project where we are removing pesticides from recycled water using carbon filtration.”

It's already been a long busy summer of consultancy for John as he jokes “I always get the difficult and hard ones and awkward ones I’m afraid, but I like the challenge of it.”

For more information about water recycling and other water resources options such as rainwater harvesting and water sharing to help groups of growers go to: https://engageenvironmentagency.uk.engagementhq.com/local...

There is still time to apply for a screening study with the Environment Agency to assess and rank water resources options to increase water supply resilience as part of a group of neighbouring farmers. https://www.gov.uk/.../how-to-apply-for-a-local-water.... The deadline for applications is the 20th July.

John also provides licensing advice. Growers should understand the conditions of any abstraction licences they may have, especially noting end dates to apply to renew in a timely way without risking them expiring. More information on renewing abstraction licences in England is available at: https://www.gov.uk/.../apply-to-renew-a-water-abstraction...