Talking regenerative agriculture

Fert Options
with Robin Boom
Agronomic Advisory Services

Regenerative agriculture is being touted by organisations such as Greenpeace as the future of farming because conventional farming – it claims – is unsustainable and environmentally damaging, and the Government is looking at funding research examining regenerative agricultural techniques. Last month Peter Barrett, owner of Linnburn Station in the dry Maniapoto region of Otago where typically only 400mm of rain falls each year, and Jono Frew, an ex-agricultural spray contractor from Otago, conducted a series of meetings throughout the country.

I attended one of these meetings, where they promoted their version of regenerative agriculture. Their system is based on a wide plethora of plant species – 16 or more – and lax grazing techniques to help build root biomass and leaving plenty of plant residual above ground to photosynthesise. These plant residuals are then treaded into the soil by grazing livestock to create a thatch layer, which soil micro-organisms break down and turn into humus. All of this happens without the use of chemicals and synthetic fertilisers.

Red flags

Soil scientists Doug Edmeades and Jacqueline Rowarth have argued that NZ farmers have been doing regenerative agriculture for many decades. And if we consider what Zimbabwean ecologist Alan Savoury calls ‘regenerative agriculture’, as a means to stop desertification in Africa, they are probably right. Savoury advocates rotational grazing of areas by livestock where animals are moved on before overgrazing, and where dung and urine are returned to the soil and uneaten stem material and seedheads are treaded into the soil.

For me there were some red flags with the Barrett/Frew roadshow as what may work in the dry Maniatoto will not necessarily work in other parts of the country. For a start, a lot of the South Island has quite good natural fertility – a fact I learned back in 1996 at the NZ Grasslands Association Conference in Nelson, where we visited a drystock farm that had Olsen P figures in the 50s, yet hadn’t applied any phosphatic fertilisers. Also at Clarendon in South Otago there is a disused phosphate mine as it is an extension of the Chatham Rise. In the Maniatoto the soils lack organic matter, not phosphate, so any practice that builds carbon in the soil is going to be good, as soil organic matter will increase water holding capacity as well as more biological life.

BOP/Waikato soils

In the BOP/Waikato region most of our soils have good organic matter levels, but are naturally lacking phosphate. At Ballantrae Research Station in the Manawatu a long-term phosphate trial showed much more humus and soil life was prevalent at high rates of fertiliser compared to where none had been applied; and, after 35 years treatment, pasture productivity was 250 per cent higher than the unfertilised area. A phosphate trial I’ve been running for the last 12 months at Taumarunui has shown a 25 per cent increase in pasture productivity to just 45kg of P/ha in a single year. So it is not a ‘one size fits all’, and when I heard that our soils had enough phosphate to last 200 years, I thought these guys don’t know what they are talking about. Pumice soils are essentially glass (silicon dioxide) and need almost everything, and raw peat soils leak phosphate like a sieve and it doesn’t hang around unless you use insoluble sources like RPR. Potassium, sulphur, boron and nitrogen too don’t hang around and need to be regularly replaced.


When asked about the economics from their regenerative agricultural system, they could not give any figures on increased profitability. But I have no doubt there is some merit in planting multiple species and lax grazing in such a dry environment. But for places where there is regular rainfall or irrigation, and where soils are naturally infertile like most of the North Island, to tell people they don’t need fertiliser is not helpful.

If you just have biology but no chemistry, plants will not grow. Whereas if you just have chemistry and no biology, they will grow as we see in hydroponic systems. Soil scientist Dr William Albrecht, a man whose approach to soils I try and follow, observed that: “Food is fabricated soil fertility”.

The opposite of ‘regenerative’ is ‘degenerative’. If you do not maintain fertility, you will have degenerative agriculture. But changing grazing management practices and introducing other plant species for drought challenged years is certainly worth considering.

Disclaimer – these are the opinions of independent agronomy and soil fertility consultant Robin Boom, of Agronomic Advisory Services. Any decisions made should not be based on this article alone and appropriate professional assistance should be sought. Robin Boom, CPAg, is a member of the Institute of Professional Soil Scientists. Ph: 0274448764. Email:


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