Wednesday, 01 January 2020 08:55

Analysis of regenerative ag needed

Written by  Dr Jacqueline Rowarth
Dr Jacqueline Rowarth. Dr Jacqueline Rowarth.

OPINION: The groundswell supporting the restoring powers of regenerative agriculture is mostly based on examples from overseas.

The big question should be, do the examples stack up in New Zealand?

If yes, no problem. If no, what might happen? Would there be any unintended consequences? 

Answering these and similar questions is the goal of scientific research. The foundation for advancing knowledge is laid by identifying the problem and then analysing what has gone before:

• What is the starting point?

• Relativities – what comparisons are being made?

• Context – what are the concerns?

• Science -- what ‘facts, evidence and data’ support those concerns?

• Alternatives – are there any with more ‘acceptable’ outcomes?

Professor Richard Teague, grazing systems ecologist and professor at Texas A&M AgriLife Research, is an advocate of regenerative agriculture, and puts the state of the research simply. 

“In science, we have to try to understand what’s going on. No single experiment solves all the problems. But all the data we’ve collected suggests that the more people who manage their soil better, either in grazing or cropping systems, the more carbon will be sequestered in the ground.” 

Regenerative agriculture as explained by Professor Teague uses cover crops, no-till, crop diversity, little or no chemical fertilisers and pesticides, and livestock integration to promote healthier ecosystems by rebuilding soil organic matter. (Soil carbon, which is over half of soil organic matter, has undisputed positive effects on soil chemistry, physics and biology.)

His description includes subdividing existing paddocks with electric fences, grazing for one to three days maximum and giving adequate recovery. In the Dallas area, he estimates 60-90 days in the growing and non-growing seasons, but in dry areas double this recovery time will be required.

Using the regenerative agriculture approach, Professor Teague states that soil carbon increase has been measured at eight tonnes per hectare per year. 

The journal article from which this figure came was authored by researchers from Universities of Georgia and Florida. It reported changes in soil carbon over a 10-year period when degraded cropping soil was returned to grazing. 

The pastures in the research were ‘managed for maximum forage production, employing N fertilisation, irrigation and selective rotational grazing with a 15 to 45-day rotation’.

The increase brought the soils from about 10 tonnes carbon/ha to 30-40 t/ha in the top 30cm. This was ‘equivalent to under native forests’. 

The authors commented that such a high rate of carbon accumulation wouldn’t be maintained indefinitely following conversion to intensively grazed pasture but that further slow accumulation might be possible. 

The authors then discussed New Zealand pastures with soil C stocks estimated as high as 109 to 138 tonnes carbon/ha. Citing the work led by Professor Louis Schipper at the University of Waikato, they pointed out that once these soils reach a higher soil carbon, they can become susceptible to carbon loss if management changes. 

Clearly the starting point, relativities, context and science are important. New Zealand soils are not degraded and the Ministry for Environment has stated that ‘soil total carbon was within target range for 95% of tested sites’.

Instigating principles out of context could have significant and potentially detrimental unintended consequences. In particular, where current management is optimal for grass harvesting by ruminants, Professor Tony Parsons (now retired from Massey University) has shown that a change in stocking rate and inputs would result in a decrease in soil carbon and more nitrogen being released to the environment. 

Professor Teague has stated that he is ‘careful not to extrapolate is the data from bite-sized, snippets to something headline-worthy’. 

The same does not appear to be true of some advocates who are promoting regenerative agriculture as the answer to climate change. It certainly might help with carbon sequestration in some degraded soils, where there is access to irrigation and nitrogen, but most of New Zealand has already done what is being promoted.

Doing better than we are already doing takes scientific research done in context, with appropriate examination of unintended consequences. Anything else could distract good farmers from managing their operations optimally with negative implications for environment and economy.

• Dr Jacqueline Rowarth is a soil scientist with a PhD in nutrient cycling. Her research has focused on phosphorus, nitrogen and carbon. 

More like this

No simple answer to soil C

OPINION: Soil carbon is not included in either New Zealand's Emissions Trading Scheme (ETS) or the proposed He Waka Eke Noa (HWEN) programme.

No out for NZ farming!

OPINION: The 2015 Paris Accord on the ‘need for an effective and progressive response to the urgent threat of climate change’, recognised the fundamental priority of safeguarding food security and ending hunger.

Questioning is not an attack!

OPINION: Scientists have been accused of mounting a sustained attack on regenerative agriculture and splitting the science community. Not all, but some.

Time to do the math!

OPINION: Confusion abounds in the discussion about agricultural greenhouse gases (GHG) and misinformation is rife.

Nutrient claims are crap!

OPINION: A debate has emerged in nutrient management and fertiliser advice, brought to a head by the hype about regenerative agriculture.

Featured

Sheep drench resistance costly

Analysis by Dunedin-based Techion New Zealand shows the cost of undetected drench resistance in sheep has exploded to an estimated $98 million a year.

Dairy sheep and goat turmoil

Dairy sheep and goat farmers are being told to reduce milk supply as processors face a slump in global demand for their products.

Hurry up and slow down!

OPINION: We have good friends from way back who had lived in one of our major cities for many years.

National

Knowing bugs means fewer drugs

A mastitis management company claims to deliver the fastest and most accurate mastitis testing available at scale for New Zealand…

Machinery & Products

AGTEK and ARGO part ways

After 12 years of representing the Landini and McCormick brands in New Zealand, Bay of Plenty-based AGTEK and the brands’…

100 years of Farmall Tractors

Returning after an enforced break, the Wheat and Wheels Rally will take place on the Lauriston -Barhill Road, North-East of…

JD unveils its latest beast

John Deere has unveiled its most powerful tractor ever, with the launch of the all new 9RX Series Tractor line-up…

Biggest Quadtrac coming to NZ!

In the biggest announcement that Case IH Australia/New Zealand has made around its tractor range, its biggest tractor is about…

» Latest Print Issues Online

The Hound

Why?

OPINION: A mate of yours truly wants to know why the beef schedule differential is now more than 45-50 cents…

Fat to cut

OPINION: Your canine crusader understands that MPI were recently in front of the Parliamentary Primary Sector Select Committee for an…

» Connect with Rural News

» eNewsletter

Subscribe to our weekly newsletter