Grower field walk at Daniel Finlayson’s property near Ngahinapouri.
For three consecutive seasons, a Foundation for Arable Research and Growers Leading Change group study was run with a group of four experienced Waikato-based, large-scale maize growers interested in alternative nitrogen sources for their maize crops.
Foundation for Arable Research senior researcher Dirk Wallace and researcher Sally Linton led the study.
“We put a call out for grower participation, and the group was set up with a researcher and facilitator from [the foundation] to start in the 2022/23 season,” Wallace said.
The objective was to identify alternative-N (Alt-N) sources that enable arable growers to maintain profit while contributing to environmental compliance.
From the 2022/23 season, the group ran on-farm try-outs, testing a range of Alt-N products on maize and measuring their impact on crop yield.
“Four Alt-N products were used: chicken manure, dairy effluent, composted dairy effluent and winter legumes.
“A huge variation in the three seasons covered by the trials offered good climatic contrast for all the different soil and contour types.”
2022/23 was the wettest season in 40 years, 2023/24 was an average season, and 2024/25 had drought conditions.
Soil testing was carried out before planting as usual, and after harvest, which proved to be very useful as it showed how much N was left in the soil.
Daniel Finlayson has owned his 190-hectare (160 ha effective) farm since 2021.
Thirty hectares are in riparian planting, 105ha in maize silage yearly, and the rest is heifer grazing and bull beef.
“We wanted to look for opportunities to improve our nutrient management, lower our carbon footprint while increasing our profit - people, profit and planet are our criteria,” Finlayson said.
“I saw the Alt-N trials as an opportunity to try and quantify and refine our N policy to be more accurate.
“We were already using Alt-N sources, but industry measuring standards for artificial N tend to overestimate use, making overall calculations hard.”
Finlayson carried out trials on two blocks.
For the first season, he used four different treatments.
“We did two seasons, so have two seasons of data,” he said.
“We had a significant response to starter fertiliser, but the two with the extra N didn’t yield any extra.”
For Finlayson, this was exciting as soil testing after the harvest showed substantial residual N in the soil.
“We realised that we were able to use 15 tonnes less side-dressed urea than we had been.”
In the second season, Finlayson tried an annual clover winter legume cover crop in another trial block.
“It was good to learn that N inputs can be reduced, profit can still be improved, and our carbon footprint reduced,” he said.
“It gave me confidence around how I operate.
“I’m very interested in bio sources and still use chicken manure and clover, and will continue to assess them with on-farm tryouts.
“It’s good to know there are options beyond a bag of urea.”
Finlayson won the 2024 Arable Awards of New Zealand - Positive Environment Impact Award.
Alan Henderson is a second-generation farmer running a 400-hectare mixed use farm with a 230ha dairy unit of 750-800 cows, calf rearing 550-560 calves yearly, 4ha of apples and nashi, a small number of beef and sheep, and 80-100ha of crops including maize, lucerne, turnips, faba beans and chicory.
He was attracted to this particular trial as he saw it as an opportunity to quantify practices he was already using with chicken manure and dairy effluent provided by his dairy unit and confirm their worth.
“The trials were grower-led with [foundation] funding and expertise to support growers with soil testing, harvesting and lab work,” Henderson said.
He put 0.5ha aside and, after soil testing, planted five different trial sectors.
“I felt it proved that using natural product builds up soil carbon, resulting in a healthy, active, biological high-performing soil medium to grow high-yielding arable crops,” Henderson said.
Natural N products could involve cover crops, livestock, effluent, chicken manure or other litter, he said.
“You want micro activity working hard and fast, building the soil microbiome using organic matter and reducing granulated N.”
Henderson believed regenerative farming was not always the best option, despite being talked about more nowadays.
He has used the concept for over 40 years.
“The whole process of environmental responsibility is having deep and active soil, using appropriate tools for your soils, and cultivation could vary between strip till, no till or full cultivation.
“You just control what you can.”