Two years of the most comprehensive programme yet on the effects of regenerative pastoral practices in New Zealand has yielded some mixed results.
Whenua Haumanu is a partnership between Massey University and the Ministry for Primary Industries through the Sustainable Food and Fibre Futures fund. The seven-year research project brings together universities, Crown Research Institutes and industry partners to assess the suitability and relevance of regenerative agriculture in New Zealand. The project is also linked with research in Australia, Ireland and South America.
The current scope of the research is large, with the intent for it to be industry led to help narrow the focus and address some of the key questions from farmers.
“We won’t be able to answer everything but the idea is to have robust engagement throughout the project to guide where it should be heading. It’s got to be driven by farmers, who are the people who are going to put all this into practice,” said programme and research lead Professor Danny Donaghy.
The most surprising result so far is the halving of nitrous oxide emissions on the diverse pastures compared to the standard pastures, irrespective of management. The measurements will be done again this year across more areas and Donaghy said they’re not exactly sure what to expect.
“This is probably because you’ve got a difference in root activity, you’ve got a difference in growth, and possibly more efficient use of nitrogen, so there is less available to be lost as gas. We are keen to see what this year’s results tell us,” he said.
This will remain a key area of focus to get a clearer picture of what regenerative practices mean for greenhouse gas emissions.
Donaghy said that scientists agree that many of the pastoral topsoils in New Zealand are saturated with carbon. Regenerative agriculture aims to build soil carbon, so the question now is, how much further can we go? And what, if any, benefit will it provide?
“The standard test depth for soil carbon is 30cm, so if we can routinely have, through species selection in pasture or through management, roots down below 30cm (which we can do), then is that going to build soil carbon below that point? That’s one of the things we are investigating at the moment.”
“Ecology 101 tells us that no matter the community – forest, grass, native or otherwise – after a year or so, about a handful of things are dominating. We found this on both the dairy and sheep farms. Eighteen different species were initially planted on the dairy pasture and 19 on the sheep pasture.
“We’re down to about eight to 10 of those species with about four of them dominating at any one time. On the dairy pasture, I took the five things that were most dominant and just sowed them and started the conversation with farmers around this idea of functional diversity.
“Instead of thinking of diversity in terms of the number of different plants that you can sow, start with thinking about what the function is you’re trying to achieve. For us, we were thinking of summer dry as an issue, we have stony soil next to the river, but we don’t want to sow exclusively summer-active species because then we can create a winter feed gap.”
Photo credit: Gerry le Roux, ScienceLens
Legumes were a must in the mix to reduce nitrogen fertiliser input, and plantain was included for its role in mitigating nitrogen losses. The species that dominated under a range of different managements trialled were ryegrass and white clover, cocksfoot and red clover, and plantain. Not surprising, when looking at the amount of breeding and selection that has gone into those varieties over the years.
“No one mix is going to solve everything on every farm, and it might not even be the pasture mix that’s the problem, it could be the management or something else holding the system back. The literature said that regarding yield, no matter how many things you put in, the yield benefits saturate at about four to eight different things in a pasture. Animal production benefits saturate at about three to four different things. This makes sense because plants that fill similar niches are all fighting for the same space.”
Much of the conversations the research team are having with farmers around functional diversity are about getting across the understanding that each different type of plant needs to be in high enough numbers to play the role it’s intended for and that the management needs to be right to avoid it being a costly exercise.
Day Zero measurements of soil bacteria and fungi were taken for DNA analysis on all farms involved in the research. Over 1400 different types of bacteria were found on the Massey dairy farm, a huge amount of diversity to start with. In comparison, the sheep pasture yielded only several hundred. This difference in number is linked to the dairy pasture being more free-draining than the sheep pasture, which is predominantly silt loam with a hard pan at around 70cm depth, and is anaerobic for periods of the year.
“This brings into focus the importance of knowing your baseline. If you’re a farmer or a policy-maker saying you want to measure several things to determine if your soils are in good health, then you really need to understand what the background levels are first.”
The likelihood of those numbers changing dramatically is unknown, as is the question of whether it’s a good or bad thing to have so many types of bacteria, as many of the species are yet to be classified.
Looking below the surface at soil health, one of the measures used is hot water extractable carbon, which is a measure of soil microbial biomass. This was higher in the diverse pastures than in standard pastures on the dairy farm.
“The regenerative treatments we’re using are giving the pasture a longer rest period, so longer rotations, and also aiming to leave more pasture behind after grazing, backing off nitrogen fertiliser and adding in other things like fish product to the soil, as it’s believed to stimulate soil microbial activity, especially fungi.
“There was also a trend for more earthworms in Year 1 under the diverse pasture with regenerative management, but the opposite happened in Year 2. This highlights the need for multiple years of data collection.”
Donaghy said that there is a bit of a question mark around the soil microbial aspect of the research, with not a lot being done currently in that area. A lot of what has been observed around soil microbial communities has been in forest communities rather than grasslands.
“You’ve got these diagrams comparing native forests with pastures, and the native forest soil is very dominant in fungi, whereas the pasture soils are dominant in bacteria, so many regenerative farmers are trying to get their pastures to be more fungally dominant, but what if pastures are naturally just bacterially dominant and all of their effort is going into changing something that might not be easily changed, or if it is changed, doesn’t have the impact that they want? We will be focusing on this and other questions in the coming year”
To date, pasture quality hasn’t shown much difference between treatments, but they expect those figures may change in line with the change of dominant species in the pasture. In the first year and a half of the project, legumes and herbs were abundant, but the team are expecting a shift towards pastures being grass-dominant, and with that will come changes in quality and potentially production.
“We are seeing some differences in the quality of the animal product, so the meat and the milk. We’ve got a student looking at amino acid profiles, and as you’d imagine, if you vary the diet, you can vary the amino acids. It’s early days for this piece of the project though.
“We’ve also seen higher lamb growth on diverse pastures, which is in line with expectations from a higher legume and herb volume in the pasture.”
A narrowing down of the measurements and focus points of the research is in store for the next few years of the project as the team figures out what farmers want to know more about and where the research can add the most value.
Exploring functional diversity more is on the list for the team, along with refining some of the measurements, especially around determining fungal and bacterial communities. The DNA measurements are progressing to targeted RNA measurements to target different groups of desirables.
“There are free-living soil bacteria that can fix nitrogen, so it would be cool if we could increase those because they would give you free background nitrogen that would save you having to buy it and apply it.”
Certain types of fungi are known to have positive relationships with plants that allow the roots to explore greater volumes of soil and to look for water and nutrients. This could potentially mean greater drought tolerance among other benefits and will be investigated further.
Animal welfare is another area that will be explored further, as well as the use of boluses to measure temperature, water intake and pH, and collars to track movements and rumination.
“We’re trying to get a handle on what’s going on below the ground, above the ground and what’s happening with the animals. The beauty of this sort of project is that we’re getting feedback and ideas from farmers. This robust engagement is what will make whatever comes out at the end of this project have a real practical value and not just be another book at the bottom of the pile.”
More: This article was made possible by Our Land & Water.
