108 | Deeper than nutrients and fertiliser inputs Glenbrook Station Trial Site with and without biological stimulants and fertiliser. Karen Phelps For generations farmers have viewed soil largely through a mineral lens focusing on nutrients and fertiliser inputs. However according to Peter Espie, managing director of Ag Science, trials and advances in technology are revealing a much more complex world beneath the surface where billions of microorganisms play a critical role in plant growth, nutrient efficiency and environmental outcomes. “In 2023 the United Nations Food and Agriculture Organisation described the soil microbiome as a game changer for agriculture,” he says. “It introduces an entirely new way of looking at soil science and functioning. Until the advent of DNA testing we really didn’t understand the soil microbiome because we couldn’t see it - it was like a room with the light turned off. Soil microbiology gives us a new way forward to achieve sustainable agricultural production.” Research undertaken by Ag Science has shown how encouraging beneficial soil biology can improve fertiliser efficiency and reduce environmental impacts. One significant trial examined the use of Southern Humates’ product. Humates are a concentrated form of organic matter created from partially decayed plant material preserved over thousands of years. They contain humic and fulvic acids, which can improve soil structure, nutrient availability, water-holding capacity and microbial activity. The field trial was carried out in Southland between 2014 and 2018. When humate was added alongside 210kg urea, applying just 25kg of humate per hectare resulted in a 28% increase in pasture production above urea alone in the first year. “The trial was repeated over four years and the same result happened every time, with humate and urea producing greater yields than urea alone,” says Peter. “The overall increase was 9.7% over four seasons in Southland. Adding humate changed biological function and changed fertiliser efficiency.” The research also showed benefits for nitrogen retention. While urea alone resulted in nitrogen leaching over winter, leaving the soil effectively back at its starting point by spring, urea combined with humate maintained higher levels of available nitrogen. “By spring, urea plus humate still gave a 20% increase in pasture production,” explains Peter. “DNA analysis showed the stimulation of soil biology meant the soil held onto nitrogen over winter, leaving more nitrogen available for early spring growth.” RURAL SERVICES » Ag Science At a cost of about 60 cents per kilogram, the addition of humate provided a low-cost opportunity to improve production and reduce nutrient losses, he says. The following winter, total nitrogen leaching from urea alone was higher than from the urea and humate treatment. The research was repeated in Canterbury at Rakaia from 2016 to 2020 with the same results. Further investigation found a direct relationship between microbial activity and nitrogen loss, with increasing anaerobic microbial biomass linked to reduced nitrogen leaching. Humate was shown to increase this microbial biomass. A larger Southland trial in 2021-2025 involving three farms and more than 600 plots produced similar outcomes, with humate application resulting in up to a 29% increase in whole trial average production and up to 11% reduction in nitrate leaching. Another Canterbury high country trial examined the addition of beneficial microbes through BioAg products, which, with fertiliser, also recorded a significant 60% increase in production. “It simply means this is a new way forward that genuinely delivers on the key goal of increasing Southern Humates Humates Improve Soil Health Fungi production, reducing nitrogen leaching and resulting in truly sustainable agriculture. Farmers have viewed this as touchy-feely stuff in the past but now the science is proving it works,” says Peter. “This is a developing area that we have to look at extremely carefully because the potential for farmers is huge. It is a no-brainer that this should be implemented on a large scale.”
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