Farm sustainabilityfund to help farming family trial biostimulant

Otago Daily Times

29-05-2025

Dewhirst Land has eliminated synthetic nitrogen from its Canterbury soils which are about to get a bacteria and fungi boost, Tim Cronshaw writes.
A Canterbury dairy farming family with a herd of 1700 cows is about to go deeper into soil health after being free of synthetic nitrogen fertiliser for three years.
Dewhirst Land has just won a $35,000 grant from The a2 Milk Company's farm sustainability fund towards a project testing bacteria and fungi added to the soil with a tailored pasture mix.
The supplier of a2 milk for Dunsandel-based processor Synlait Milk will foot the remainder of the bill for the $90,000 project on part of the 435ha property in Selwyn.
As a structural engineer by trade, managing director Isaac Williams takes an engineering lens to the farm he jointly manages with his wife's family.
He said the family had been running regenerative, diverse multi-species pasture for three or four years on about 85% of the milking platform.
This had been producing good results and they looked to push this further with a trial based on a RespondBio biostimulant system.
"We are a farm trying to push the boundaries a wee bit and be innovative in sustainability and regenerative pastoral farming.
"In doing so it's a bit of a space where there's no real hard and fast research or evidence supporting it, not because it's not working, but because it's just that nobody has put the money into it."
Mr Williams said they initially dismissed RespondBio as another "sales pitch", before revisiting its fungi and bacteria-enriching potential to test it for themselves.
"We had always known with the soil health on Canterbury dairy farms it is a challenge to maintain high populations of fungi and bacteria, particularly fungi as the bacteria we've still got.
"For us, we have been very much on that journey with agronomists and soil specialists Agrownomics and AgResearch who have been doing some trials on our farm as well. Time and time again the fungi side of things had come up."
Fungi helped to breakdown organic matter and spread and mobilise nutrients within the soil and between the root systems, he said.
"We asked ourselves how we could get more fungi and nobody really had an answer and I recalled this conversation that RespondBio had floated to us about fungi and bacteria and we picked up the phone. The prices were a bit up there and as a structural engineer by trade I'm all about numbers ... The numbers they had were relative to a North Island system which didn't really relate to our system here in Canterbury. So I told them if we are going to do this I wanted to substantiate it with our own measurements and track it, but by the time you factor in the product cost and the time doing the recording I didn't know if it would stack up as a trial."
However, the claims for substantial increases in dry matter yields were appealing as it would mean they could reduce their supplementary feeding of palm kernel extract by growing more pasture on the farm.
About the time they were toying with canning the idea, they came across a2 Milk Company grants.
Mr Williams said they were pleased to get the funding to progress the project after preparing a proposal with input from their agronomists and AgResearch.
Dewhirst Land will begin the trial over one year on 40ha in about October.
This land will be split into two parts of four paddocks each, with one of the paddocks in conventional multi-species pastures as a control site, another sown in a customised dairy seed mix with no biostimulant and the other two paddocks sown in the seed mix with the biostimulant. This will be repeated at another site.
"The idea there is we get a feel for whether it is the dairy seed mix or the bacteria and fungi which are doing wonders. So we can control for those two things to get some idea of what is giving us the best bang for buck. If it's successful we will look to roll it out across our farm and if it's not we carry on."
Dewhirst Land is part of several benchmarking groups as the only farm with zero nitrogen and growing and feeding well above average pasture rates.
Mr Williams said the farming system was working and he credited his father-in-law for making the change.
"I don't think anyone's excited about removing nitrogen from the system when it has for so long been associated as arguably almost an additional feed as you just put it on and get new grass. From a mathematical production point of view I understand it, but we've been on a journey with a focus on soil health for five years now and the soil health has come a long way."
Nutrients are added to plant leaves via foliar applications by PFA Contracting rather than the soil at Dewhirst Land, with pastures added with fish hydrolysate soil improvers, seaweed, amino acids, potassium humate and fulvic acids which are tailored every grazing round.
Depending on the time of year they might do a pre- and post-graze spray of paddocks to get trace elements and nutrients into feeding cows, and follow this with a nutrient mix to improve soil and plant health.
Over the past two years they have been harvesting about 16.2 tonnes of dry matter to the hectare compared with an average 15t/ha to 16t/ha in central Canterbury.
"This season coming up we will be more than that."
Only 15% of the farm remains in conventional ryegrass and clover pastures, which also go without synthetic nitrogen. Nor are their nearby 220ha support blocks fertilised with nitrogen.
Mr Williams said there were still costs involved as they had to pay for other products and higher spreading costs, but they were at a point they could reduce some of this soon on balanced soils.
"We have also partnered with Synlait and are doing full farm soil testing and they are helping support us to do that. Every paddock will be tested every season. The idea is Synlait's milk has a sustainable market placement adding value to their customers."
Other ongoing projects are soil carbon measurements, methane inhibitors via the seaweed and technology measuring cow health in the rumen.
Another interesting part to Dewhirst Land's system is it operates Roto Rainer irrigators instead of centre pivots which partner well with multi-species pastures as they respond well under moisture stress.
Leaching losses monitored via modelling remain relatively high as the farm has a lot of nitrogen-fixing clover in the system.
"This is where we hope the fungi and bacteria will help redistribute that nitrogen to the plants that need it, rather than just having it fixed in the clover and immediately around it. So we do lose a bit and we are still very much learning."
Multi-species pastures include three different clovers, Italian and other ryegrasses, tetraploids, plantain, chicory, fescues, lucerne and timothy.
A trial of sunflowers in a paddock was not repeated because of the mess left after grazing.
The cows complete about 10 grazing rounds per paddock for the season. Three plate meter readings will be taken of the pasture's dry matter cover before and after each grazing round, followed by a pasture cut which will be bagged, then sent for the testing of herbage data as well as plant sap testing for the nutrient uptake.
Then the dry matter percentage is monitored with the initial wet weight gathered for each cut compared with the residual result to get an exact picture of each yield. This is repeated for each paddock over the season for a total of 80 herbage and 80 plant sap tests.
On top of this will be the trial's 16 soil tests with the soil's microbiology also to be analysed by Soil Foodweb for a micro-organism count in the soil before and after the trial.
As a larger farm, Dewhirst Land typically runs its cows in four herds with paddock-to-production performance also to be tracked.
Some of the split herd are winter-milked with the herd generally milking twice a day during the peak of the season. Up to 30% of the herd is reduced to once a day in the shoulder of the season if they need their condition improved or for animal health reasons.
Mr Williams said the family was grateful for the support of The a2 Milk Company to do the work.
"This project aims to enhance the farming system, improve the profitability of the farm to ensure the land is protected for future generations and also maintain the welfare of our cows. Through this project we hope to produce beneficial results that can be shared with the wider industry."
A total of 19 projects received grants from the $575,000 fund, including 12 in Southland and Canterbury, with the rest in Australia.
They included initiatives reducing greenhouse gas emissions by replacing diesel operated machinery with electric machinery run through solar, and building calf sheds to provide shade and shelter.
The a2 Milk Company chief sustainability officer Jaron McVicar said it was encouraging to see the impact the fund was making for positive environmental outcomes on farms.