The Contested Evidence, Steelmanned

#An 85% difference you cannot see

Twenty-three fence lines across South Africa. On one side of each, a farmer running roughly 85% higher grazing density than his neighbour — same rainfall, same soils, same vegetation, both under consistent management for fifteen years. If density does what the courses say, that is the cleanest natural experiment you could ask for.

Eighty-two per cent of those fence lines showed no significant difference in vegetation greenness, bare ground, grass cover or woody cover (Venter, Cramer & Hawkins 2019).

That result is South African, recent, peer-reviewed and inconvenient — and it is not the whole story. Both sides get their best shot here, because you are about to spend real money on the answer.

#The sceptical case, at full strength

Do not weaken this. It is the strongest evidence in the argument.

Southern Africa ran the trials the rest of the world quotes. Reviewing more than 50 grazing experiments in southern Africa, O'Reagain & Turner concluded that continuous and rotational systems differ little in their effect on range condition or animal production (JGSSA 9(1), 1992). Import Missouri or New South Wales confidence about "the system" and you are arguing against a local literature.

The meta-analysis. Hawkins ran the first quantitative meta-analysis of high-production grazing against season-long continuous grazing: 75 datasets, five countries (Argentina, Australia, Canada, USA and Zimbabwe), 1972 to 2016. The result: no significant difference in plant basal cover, plant biomass or animal gain (p > 0.05). In her own words, "if animal impact is occurring during HPG, it has no effect on production", and it "does not warrant the additional inputs (infrastructure and labour) that the approach requires" (Hawkins 2017).

Two things make that hard to wave away. It was funded by the SA Red Meat Research and Development Trust and Cape Wools SA — industry money, not activist money. And it closes the easiest escape: camp size (0.75 to 350 ha) and trial duration (2 to 13 years) did not affect the effect sizes. "The trials were too small and too short" is the standard rebuttal; this dataset does not carry it.

The real-farm answer to "trials cannot capture adaptive management". Venter and colleagues surveyed 48 working South African farms under consistent management for 15 ± 0.8 years, across five biomes and a 150–850 mm rainfall gradient, with 23 fence-line contrasts at that 85 ± 5% density difference — and got the 82% null result above. Their sentence is unambiguous: "continued advocacy for extreme forms of rotational grazing management is unfounded."

And the most recent review does not rescue it. Meyer & Schmiedel reviewed roughly 17 southern African continuous-versus-rotational studies and found the outcomes contradictory and inconclusive, with stocking density and herbivore composition differences making comparisons ambiguous — and noted the debate carries a political charge, since continuous grazing maps onto communal farming and rotational onto capitalised private farms (AJRFS 43(1), 2025). Hold that one at arm's length: the paper is paywalled, and the study count and conclusion above come from published summaries rather than the full text.

#The rebuttal, at full strength

Now the other side, and it is not mysticism.

Teague's objection is methodological. Most experimental "rotational" treatments were never run under the protocols supposed to produce the outcomes: paddocks grazed too long, recovery too short, trials too brief, and the whole-ranch adaptive decision-making that is the actual practice absent entirely. Comparing a badly specified rotation with continuous grazing tests nothing about a well-specified one (Teague's rebuttal). If recovery is the design variable, a trial that fixed the rotation to a calendar was never testing the thing.

And there is a measured effect inside the sceptics' own dataset. In Hawkins's meta-analysis, animal density significantly raised the effect size for plant basal cover (p = 0.009), and mean annual precipitation raised it too (p = 0.030). That is a density effect on an ecologically meaningful variable, found by the study usually quoted as the refutation. Any flat claim that density does nothing is wrong.

Here is the qualifier neither side gets to skip. Those relationships hold for plant basal cover only. Neither precipitation nor density affected the effect sizes for plant biomass, animal gain or average daily gain (p > 0.05). So the honest sentence is:

At higher rainfall, high-density grazing is associated with better ground cover. It is still not associated with more production anywhere on the gradient.

That sentence should end most of the arguments you will have at a farmers' day. "AMP pays in the wetter half of South Africa" is, on this evidence, a cover argument. Presenting it as a production argument is a defect.

#The live contradiction: fire and carbon at Ukulinga

To see how unsettled this field is, look at one long-term experiment where two recent studies point opposite ways.

Against frequent fire. Sixty-four years of annual burning at Ukulinga lessened soil organic carbon and nitrogen in humid subtropical grassland (Global Change Biology, 2021). Separately, the national review of land use and soil organic matter reports long-term South African burning plots at 70% lower organic carbon in the top 0–10 mm — 0.8% against 2.7% (du Preez et al. 2011). That is the number that gets quoted.

But quote both numbers or neither. The same paper reports that over the 0–100 mm layer the difference was only 12% lower organic carbon and 13% lower total nitrogen. A 70% loss and a 12% loss are the same plots at two depths. Sampling depth is doing most of the rhetorical work here — and once you notice, you will notice it everywhere in regenerative marketing.

For frequent fire. A 2025 study on the same experiment reports early-season frequent prescribed burns producing greater soil organic carbon concentrations and enhanced sequestration rates than longer burn intervals, accumulating over a 20-year window (African Journal of Ecology, 2025).

Same site. Opposite conclusions. Depth, burn season and grazing exclusion are the likely reconciling variables, but nobody has settled it. If sixty-four years of data cannot produce a stable answer about fire and carbon, treat any confident claim about what your grazing did to your soil carbon with the suspicion it deserves.

#The money, modelled honestly

The best South African whole-farm financial modelling of a regenerative transition is a Stellenbosch master's thesis on a "typical farm" in the Western Rûens — a multi-period whole-farm budget assessed on internal rate of return and net present value over twenty years (Hayward 2021).

Three things to read carefully before using that thesis in either direction:

1. The productivity gain was an assumption, not a finding. With limited information available on high-density grazing under regenerative practice in the Western Rûens, the thesis says, discussion participants were asked to suggest an increase in carrying capacity based on their personal experience and expert knowledge. The step from 4.5 to 5.5 small stock units per hectare was put into the model by expert opinion. A model cannot validate its own input. If you take one habit from this module, take that one: read the provenance, not just the number.
2. Raising the stocking rate was not unambiguously good. Going from 4.5 to 5.5 SSU/ha produced an expected increase in IRR of 4.17% and a decrease of 1.82% in NPV — better return on capital, worse long-term cash flow. The thesis concludes capacity should only be increased by 1 SSU/ha over twenty years. Two headline financial measures pointing in opposite directions is what a real trade-off looks like.
3. It is the wrong farm for most of this course. The Western Rûens is a winter-rainfall, conservation-agriculture, cereal-and-sheep system. Its input-cost conclusions travel — the gains came from cutting purchased inputs and rebalancing the enterprise mix, while capital re-tooling destroyed value. Its numbers do not travel to Highveld sourveld beef, Karoo small stock or bushveld.

#What you actually do on Monday

None of this says "do nothing". It says something narrower: be clear about what you are buying.

The profession's own landing point, after nearly six decades of published South African grazing research, is not a system. It is adaptive grazing management — deciding in response to conditions rather than following a recipe (AJRFS 42(1), 2024). Which raises the next lesson's question: if the case for expensive subdivision is this thin, what happens when you replace the fence with a person?