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Duckweed, the UK needs it.

As the UK’s drought continues and the Maize for winter feed withers in the fields we need an alterative. Our farmers are already feeding winter food to their livestock. There is an option and it is called Duckweed. That green stuff floating in our ditches and rhynes. It may well provide the alterative to farmers having to cull their livestock or buy in expensive food, if they can find it?

Even if the rain comes now, August 2026, the loss of crops will still create feed shortage through the winter. With wetter warmer winters Duckweed may be the best hope to create the feed the farmers need.

Duckweed production provides: speed, protein, and simplicity.

  • Rapid growth — Duckweed can double its biomass in 24–48 hours under optimal conditions. That’s faster than soy, rye grass, alfalfa, or most forage crops.
  • High protein content — Depending on species, protein ranges from 25–45%, comparable to soy meal.
  • Low resource demand — It grows on shallow water with minimal inputs, making it ideal for marginal land or integrated farm systems.
  • Environmental benefits — It absorbs nitrogen and phosphorus, helping clean agricultural run-off.

For UK farmers facing tight margins and environmental regulation, this combination is compelling alongside the cost of deployment on fields too dry to cultivate and plant.

An existing setup

Scalable

It has been done before at scale. One of the most notable large‑scale experiments happened in the 1980s–1990s, when Nestlé supported duckweed cultivation systems in parts of South America, especially in Peru and Colombia.

Here’s what that system looked like:

  • Integrated lagoons — Farmers built shallow ponds fed by nutrient‑rich water from livestock or food‑processing waste streams. These can be simple plastic channels laid on the ground
  • Continuous harvesting — Duckweed was skimmed daily, dried, and mixed into feed for pigs, poultry, and fish.
  • Circular nutrient flow — Wastewater fed the duckweed; duckweed fed the animals; animals produced manure that fed the lagoons.
  • Low‑tech, high‑yield — The system required minimal machinery, making it accessible to smallholders.

Results: Farmers reported improved feed efficiency, reduced reliance on imported feed, and cleaner water leaving the farms. Nestlé’s interest was tied to stabilising local supply chains and improving sustainability metrics long before ESG became mainstream.

The UK can borrow heavily from this model — but with modern upgrades. The author has since 2015 been involved in providing project vision and supporting the design of Duckweed schemes in Peru, Jordon, South Sudan , India and other countries with water and food poverty.


Why Duckweed Fits the UK’s Agricultural Landscape

The UK has several structural advantages that make duckweed adoption easier than in many countries:

  • Abundant rainfall → consistent water availability for ponds. Our warmer wet winters deliver that water.
  • High livestock density → steady nutrient streams for duckweed growth.
  • Pressure to reduce soy imports → duckweed offers a domestic alternative.
  • Strong research institutions → ideal for optimising strains and systems including Brymore Academy.
  • Contractors and farmers able to install the systems quickly and efficiently.
  • No Effluent

Duckweed can be integrated into:

  • Mixed farms — where nutrient flows are already diverse.
  • Dairy farms — using slurry lagoons as growth beds.
  • Poultry operations — replacing part of soy meal.
  • Aquaculture — especially trout and carp systems.

How do you produce Duckweed?

at the most basic level a channel/ raceway with a water containing nutrients being being forced around a channel with Duckweed growing on the surface. 25% is harvested every day.

The plan shows a typical closed circulating raceway,

Growing medium can be water with added nutrients or effluent containing nutrients that duckweed will clean as part of the duckweed production process.

How do you feed livestock with Duckweed?

  • collect it daily,
  • a quick wash, using water you have already cleaned.
  • press to remove free water and it can be fed wet directly to livestock.
  • No complicated machinery and what equipment is needed can be fabricated by a competent local fabricator.

Duckweed will clean water

Duckweed is a fast-growing aquatic plant that naturally purifies water by absorbing excess nutrients, heavy metals, and other pollutants, making it an effective and sustainable water-cleaning solution.

It can clean effluent. Be used as sewage treatment plant because it converts nutrients to high protein biomass.

Mechanisms of Water Purification

Duckweed, belonging to the Lemnaceae family, cleans water primarily through phytoremediation, where it absorbs contaminants directly from the water column. It rapidly takes up nitrogen and phosphorus, which are major contributors to algal blooms and eutrophication, effectively reducing these nutrients by up to 63–65% in wastewater over a few weeks earthecobalance.com+2. The plant also absorbs ammonia, heavy metals, boron, and organic chemicals, helping to protect aquatic life and improve water quality earthecobalance.com+2.

Physical and Ecological Benefits

Duckweed forms dense mats on the water surface, which block sunlight and suppress algae growth, improving water clarity and oxygen levels biologyinsights.com+1. Its small root systems stabilise water, reduce turbulence, and allow suspended solids to settle, further enhancing purification biologyinsights.com. By trapping pollutants in its biomass, duckweed acts like a natural sponge, though regular harvesting is necessary to prevent re-release of stored contaminants earthecobalance.com.

Applications

Duckweed is used in wastewater treatment systems, agricultural ponds, and small-scale fish farms, offering a low-cost, environmentally friendly alternative to chemical treatments. It can remove up to 84% of chemical oxygen demand (COD), 87% of total nitrogen, and 85% of total phosphorus in controlled studies, demonstrating its effectiveness in both municipal and rural settings impress-he.eu. Additionally, harvested duckweed biomass can be repurposed as fertiliser, animal feed, or even human food, adding value to its water-cleaning role earthecobalance.com+1.

Summary

Duckweed is a multifunctional, sustainable solution for water purification. Its rapid growth, nutrient absorption, and pollutant-trapping abilities make it ideal for improving water quality in ponds, rivers, lakes, and wastewater systems, while also providing ecological and economic benefits earthecobalance.com+3.

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Severn Estuary Forum 2017

The Severn Estuary Forum met for its annual meeting 2017 in Bridgwater, Somerset on the 5th October following hard on the heels of Question Time and the Antiques Road Show at the McMillian Theatre.

An event to see people working together to resolve climate change, flood risk and wildlife preservation it was not.

Richard Hickmet the High Sheriff of Somerset opened proceedings.

The day was split into three sessions and some notes on the highlights follow.

Energy and Climate Change

Session Chair SDC councillor Ann Fraser MBE introduced the session noting the increased trade (marine aggregates) going through Dunball now rising to 70,000T per year as a reflection of increasing economic trade. Fortunately, Ross Edwards in his following update on Hinkley Point C (HPC) noted that their aggregates jetty being built as part of the enabling works was still underway. The real reason for Dunball’s growth was more to do with HPC immediate need rather than some wider reason. The irony of the councillors assumptive claim was not lost.

Ross Edwards (EDF) was able to explain, whilst maintaining a serious face, the extreme lengths that EDF were going to protect the beach from the small feet of a jack up barge and a few discreet foundations. Yet another large corporate organisation feeling the need to succumb to the irrational demands of the modern environmentalist. He also noted that EDF had spent £20M on road improvements as part of the HPC project enabling works.

Dr Judith Wolf of the National Oceanography Centre in Liverpool provided a fascinating talk that actually dealt with the session subject. The moderating impact of the edge of the continental shelf in dissipating energy should make us all worry a little less about that large piece of a volcano that threatens to slide into the sea in the Canaries at La Palma causing a tsunami. The great flood of 1607 also got a brief note and it was not a tsunami.

What was more important was Dr Wolf’s comments on global warming and the best scenario of sea level rise being 0.5m and the worst at nearly  2.0m. Dr Wolf confirmed they really don’t know the figure as no one knows how the melting polar ice caps will impact on the world. It was received with little or no comment. 2.0m is around twice the figure that the EA is using for the Bridgwater Tidal Barrier (BTB).

Planning Governance & Flood Risk

Andy Hohl (EA) project manager of the Bridgwater Tidal Barrier project explained the mechanism of the floodgates but avoided the mechanism of the planned flood defence system.  A diagram was shown showing the planned flooding of Chilton Trinity and Pawlett Ham’s when there is coincident high tides and storm surges. It is an event that will increase in intensity and frequency as sea levels rise and after a few events will have poisoned the land.

River Parrett at Chilton Trinity and Pawlett Hams; EA flood model Bridgwater Tidal Barrier 5th October 2017; How the River Parrett will increasingly flood the Levels

The EA missed the opportunity to explain why a tidal barrier is to be built in Bridgwater rather than the conventional locations at the mouth of rivers such as at Newcastle and Barking.

Mr Hohl was asked what comes after rising sea levels makes the Bridgwater Tidal Barrier ( gate and river banks) ineffective in protecting the area from the sea. Apart from some irrelevant comments about things being done today, there was no answer about tomorrow. Tomorrow, if Dr Wolf is correct, will be only 50 and not 100 years away before a replacement solution is needed.

Wessex Water’s Lucy George gave an interesting talk on the construction of the new sewers being built around Bridgwater. Clever engineering in bad ground.

Protected Sites and Species
Alys Lavers the WWT manager at Steart gave an update on the last 3 years entitled Climate Change, Flood Risk and Community Action. It has obviously become a go to place for students studying for degrees and PHD’s. Even some elver’s have apparently decided it’s a great place deciding that the swim to Oathe and the freshwater rivers of the Tone, Yeo, Parrett and beyond was simply not worth the effort and turned right into the Steart reserve. Whether that was in the EIA and is safer than getting past the locals elvering is no doubt a study in itself. However a look at the IDB asset map apparently showing every route to freshwater blocked by a clyce  does not paint a promising future for the lost elvers.

Ms Laver was also remarkably candid about Steart. That there would be no facilities built there apart from the existing toilets. No chance of a place to shelter from the elements and have a cup of tea. Little chance then that Steart will deliver the promised economic contribution when planning permission was sought by the EA. Someone in the audience from Burnham on Sea said it was difficult to find and Ms Laver explained that the lack of signposting was deliberate. Apparently keeping the number of visitors down was done for the benefit of the locals.

What was apparent to many in the audience was that WWT Steart is really only interested in the right sort of visitor; academia and other suitable people. The ordinary taxpayers who paid for Steart from their taxes (that is where the EA get its money from) most definitely not welcome.

Rob Shore WWT, session chairman and coordinator of the Severn Vision introduced the document that was first published in January 2017. What is interesting is the ambition of this recent document. A saltmarsh from Dunball to Highbridge. The proposal outlined in this document is clearly in line with the EA’s and SDC’s current strategies set out in the Shoreline Management Plan and Parrett Estuary Flood Strategy.

The map below was generated from the Severn Vision interactive map. If you live around the Severn Estuary its worth checking out the aspirations of the various wildlife organisations.

Areas of Potential Saltmarsh

One cannot help but feel that the EA and various wildlife organisations including WWT  have the ambition to turn the coastal part of Somerset into a wildlife theme park.   Trading off the land in Somerset for planning gain elsewhere such the Bristol Ports deal where Bristol gets the economic benefit and people in Somerset beyond made to feel to feel uncomfortable in their own countryside is unacceptable. Climate change should not be used as  little more than a Trojan Horse by organisations with an overblown sense of morality and entitlement.

A question on the morality of an island that cannot feed itself flooding food producing farmland to create saltmarsh was quickly pushed to one side.

Finally a question about mitigating the noise from exploding old military ordnance being found as part of the HPC outfall construction work. Ordnance, when located, is subsequently blown up by the Navy’s bomb disposal team; it did not find someone willing and able to answer it.

Observations

What was quite clear was climate change and rising sea level is really only a device and agenda for wildlife organisations to pursue the expansion of wildlife habitat.

There was no big picture presented,  no key numbers and no one to provide context as to how the wildlife of the Severn Estuary, ordinary people and business might co-exist. Key local councillors present on all the flood committees, Wessex, the drainage boards and the SRA were with the exception of Ann Fraser notable by their absence. Perhaps there were no expenses paid for attendance. Councillor Fraser it was noted in the Speaker Summaries although not an engineer had been “instrumental in leading a technical review of the flood risk in Bridgwater”. The Somerset Rivers Authority is no better with regard to engineering. There is a disturbing and dangerous precedent of non-qualified people in influential positions shaping Somerset’s flood and climate change plans. Google and mobile phones do not make an expert. 

There is simply no leadership or vision when we should be looking forward not 100  years but perhaps 2 to 300 years. Sea level rise is not stopping and schemes such as the Bridgwater Tidal Barrier that just look forward 100 years and stop with no apparent reason defy reason and responsibility; what is the plan afterwards? there isnt one.

Perhaps worst of all for an event sponsored by my own institution, the Institution of Civil Engineers, there were no engineers representing the many companies making money from climate change. Engineer’s created the landscape we have and the current generation should be leading process of planning for our future but seem to have abdicated their interest or responsibility in shaping the land bordering the Severn Estuary.

Somerset and the other counties of England and Wales that border the Severn Estuary need to have a serious conversation and take control of climate change issue at a regional level. The situation needs a champion with authority and knowledge.