Mesquite is an introduced tree that now covers about 1.473 million hectares of the Northern Cape — roughly 4% of the province. A measured stand there transpired 57 mm of water a year, and clearing it would save an estimated 345 cubic metres of groundwater per hectare, per year.
That's the argument. Below are the sources for it — and, more usefully, the three things we could claim off those numbers and won't.
Because of everything on this site, this is the claim most likely to be greenwashing. So every figure has a named study behind it, and where the evidence stops, we stop.
It was planted here. On purpose.
Nobody snuck mesquite into South Africa. The Agricultural Research Council (ARC) records that Prosopis was actively planted across four provinces "from the late 1800's, until as recently as the 1960's", as fodder, fuel and shade for arid regions with few indigenous trees. The invasive forms today are Prosopis glandulosa var. torreyana, P. velutina and their hybrids.
A remote-sensing study by Van den Berg, Kotze and Beukes in the South African Journal of Geomatics (2013, 2(2)) found Prosopis cover in the Northern Cape reached 1.473 million hectares — 4% of the province — by 2007, at a mapping accuracy of 72%. Nationally, a 2021 open-access review in Sustainability cites 1.8 million hectares under Prosopis, and spread in the Northern Cape of roughly 15% a year in upland areas and up to 30% a year in riparian areas — along the watercourses, where it does most of its damage.
Two honesty notes before we go further. That measurement is from 2007. And it describes the area invaded, not solid mesquite — density varies enormously across it.
How much water
Dzikiti and colleagues at the CSIR instrumented a Prosopis stand on an episodic river floodplain in the arid Northern Cape. From Journal of Arid Environments (2013, 90, 103–113):
- Total transpiration by the stand: 57 mm per year.
- Clearing it would prevent the loss of 345 m³ of groundwater per hectare per year.
- In spring, savings of up to 70 m³ per month per hectare cleared.
345 m³ is 345 000 litres. Out of groundwater. In a region that gets under 300 mm of rain a year.
The mechanism is the roots. The ARC records Prosopis tap roots at 58 metres deep — reaching water that grazing plants and indigenous trees simply cannot compete for.
For scale, Le Maitre, Forsyth, Dzikiti and Gush estimated in Water SA (2016, 42(4)) that invasive alien plants reduce South Africa's water flows by 1 444 million m³ a year, 2.88% of naturalised mean annual runoff — all invasive species, not mesquite alone.
The multiplication we're not doing
Here's the tempting move. Multiply 345 m³ per hectare by 1.473 million hectares, put the answer on the packaging, watch it get shared.
It would be wrong.
Dzikiti's figure comes from one dense stand sitting on accessible groundwater. Van den Berg's hectares run all the way down to scattered trees on dry upland. Applying a dense-floodplain rate across an entire province isn't evidence — it's a press release.
If you ever see a single enormous litres-saved number on a bag of anything, that is almost certainly where it came from.
What the law says, including the inconvenient part
Mesquite is listed under the National Environmental Management: Biodiversity Act (Act 10 of 2004) and its Alien and Invasive Species Regulations — but not uniformly, and the Northern Cape is the awkward exception. Per the ARC it is Category 1b in the Eastern Cape, Western Cape, Free State and North West, meaning it must be controlled and removed where possible. In the Northern Cape it is Category 3 — existing trees may remain — except in riparian areas, where it is Category 1b. No trade, propagation or planting is permitted anywhere it's listed.
So the accurate sentence isn't "mesquite is banned in the Northern Cape". It's that the worst infestations — along the watercourses, spreading at up to 30% a year — carry the strictest category, while the province's standing trees are tolerated because there are far too many of them to do anything else.
Weaker claim. Truer one.
Who actually does the clearing, and it isn't us
It isn't any beverage company either. It's overwhelmingly a state programme.
Working for Water launched in 1995. The Department of Forestry, Fisheries and the Environment states it has cleared more than one million hectares and provides jobs and training to approximately 20 000 people a year, 52% of them women, across 300+ projects.
The most rigorous independent assessment is van Wilgen, Wannenburgh and Wilson in Biological Conservation (2022, 274, 109741). Between 1998 and 2020 the programme spent an average of ZAR 310 million a year (2020 values), created the equivalent of 8 113 full-time jobs, and controlled about 76 000 sites covering 2.7 million hectares — roughly 14% of the estimated invaded area. Over a quarter of that wasn't in priority areas, and national surveys still suggest invasions have continued to grow.
Two decades and billions of rand, and the problem is still getting bigger. Anyone selling you a drink on the promise that it fixes this is overselling.
So what does a pod harvest actually do?
Picking pods doesn't fell a tree. It removes the fruit. Anyone who tells you that buying a bag of anything clears hectares of invasive trees should be asked which hectares.
What pod removal does affect is dispersal — and dispersal is how mesquite wins. The ARC describes it plainly: seed is spread by animals that browse the pods, or washed by floodwater into floodplains, which is how those riparian thickets form in the first place. The Sustainability review adds that the absence of natural seed-eating insects here preserves that seed for years.
Which is exactly what South Africa's biological control programme has spent decades trying to fix. The ARC records its initial focus as "to reduce the viable seed load", and two seed-feeding weevils — Algarobius prosopis and Neltumius arizonensis — were released for that purpose.
So here's the honest statement of what a mesquite harvest is: it pulls the same lever as the state's biocontrol programme — reducing the seed load — by hand, by people, for money.
A pod in a roaster is a pod that isn't being eaten by a goat and dropped, scarified and ready, downstream.
The three things we're not claiming
Not because they'd be hard to write. Because we can't show you the numbers:
- That your bag clears a measurable number of trees, or hectares.
- A litres-saved figure per bag.
- A count of jobs created.
When we have audited figures, they'll be published here with the method attached. Until then, nothing.
And here's what needs no study at all: the pods come from trees already standing that nobody wants. Nothing is planted, irrigated or cleared to grow them. Coffee is a cultivated crop that needs land, water and inputs. That's the comparison that matters.
Found, not farmed. That part we can prove.
The questions we actually get asked
Is mesquite an invasive species in South Africa?
Yes, under the Alien and Invasive Species Regulations of the National Environmental Management: Biodiversity Act — Category 1b in the Eastern Cape, Western Cape, Free State and North West, and Category 3 in the Northern Cape except in riparian areas, where it is Category 1b.
How much of the Northern Cape is covered by mesquite?
About 1.473 million hectares, or 4% of the province, measured by satellite in 2007 and published in the South African Journal of Geomatics in 2013. The national estimate is around 1.8 million hectares.
How much water does mesquite use?
A CSIR study of a stand in the arid Northern Cape measured transpiration of 57 mm a year and estimated clearing it would save 345 m³ of groundwater per hectare per year. Prosopis tap roots have been recorded at 58 metres deep.
Does harvesting mesquite pods help clear the trees?
Not directly — picking pods doesn't remove a tree, it removes seed. Mesquite spreads through pods eaten and scattered by animals or carried by floodwater, and South Africa's biological control programme released seed-feeding weevils specifically to reduce the viable seed load. A hand harvest pulls the same lever. It is not clearing, and we don't call it clearing.
Who clears invasive alien plants in South Africa?
Mainly the state, through Working for Water, run by the Department of Forestry, Fisheries and the Environment since 1995. A review in Biological Conservation (2022) found it spent an average of R310 million a year from 1998 to 2020 and treated 2.7 million hectares — about 14% of the invaded area — while invasions kept growing.
How can I tell if an environmental claim is greenwashing?
Ask for a number with a unit, a named source you can read yourself, and a mechanism that matches the claim. And be wary of one very large litres-saved figure: it usually comes from multiplying a per-hectare research result across a whole region.
Sources
- Van den Berg, E.C., Kotze, I. & Beukes, H. (2013). Detection, Quantification and Monitoring of Prosopis in the Northern Cape Province of South Africa using Remote Sensing and GIS. South African Journal of Geomatics, 2(2). 1.473 million ha; 4% of the province; 72% accuracy.
- Dzikiti, S., Schachtschneider, K., Naiken, V. et al. (2013). Water relations and the effects of clearing invasive Prosopis trees on groundwater in an arid environment in the Northern Cape, South Africa. Journal of Arid Environments, 90, 103–113. 57 mm/yr; 345 m³/ha/yr; 70 m³/month in spring.
- Agricultural Research Council (ARC), Plant Health and Protection — Mesquite / prosopis: Prosopis species (Fabaceae). Planting history; NEMBA categories by province; 58 m tap roots; seed dispersal; biological control agents.
- van Wilgen, B.W., Wannenburgh, A. & Wilson, J.R.U. (2022). A review of two decades of government support for managing alien plant invasions in South Africa. Biological Conservation, 274, 109741. R310 million/yr; 8 113 FTE jobs; 2.7 million ha; ~14% of invaded area.
- Department of Forestry, Fisheries and the Environment (DFFE) — Working for Water (WfW) programme. Launched 1995; >1 million ha cleared; ~20 000 people a year; 52% women; 300+ projects.
- Le Maitre, D.C., Forsyth, G.G., Dzikiti, S. & Gush, M.B. (2016). Estimates of the impacts of invasive alien plants on water flows in South Africa. Water SA, 42(4). 1 444 million m³/yr; 2.88% of naturalised MAR.
- Ravhuhali, K.E., Mudau, H.S., Moyo, B., Hawu, O. & Msiza, N.H. (2021). Prosopis Species—An Invasive Species and a Potential Source of Browse for Livestock in Semi-Arid Areas of South Africa. Sustainability, 13(13), 7369. 1.8 million ha nationally; spread rates; dispersal by livestock and flooding.