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Introduction New Zealand farmers often face two major challenges: nutrient loss from soils and the impacts of dry conditions. Dr Gordon Rajendram says solid humates and biochar, both derived from plant-based materials, can be valuable tools in addressing these issues. Used in soils or as part of animal feed, they help retain water and nutrients where they are needed most [1]. “The key is getting more value from every drop of water and every kilogram of fertiliser,” says Dr Rajendram. “Humates and biochar work with nature to do exactly that.” Humates: Feeding Soil and Livestock Humates are rich in humic and fulvic acids, typically sourced from lignite (brown coal) [2]. With a naturally high cation exchange capacity (CEC), they hold onto water and nutrients, keeping them available to plant roots [3]. By binding with nitrogen compounds, humates can reduce nitrate leaching, one of the biggest environmental issues facing New Zealand’s pastoral farming systems. They also limit nitrous oxide emissions, a potent greenhouse gas, by locking nitrogen into the soil. Humates stimulate beneficial soil microbes and improve soil structure. When included in livestock feed, they aid digestion, boost mineral uptake, support immunity, and help control parasites [4]. Healthier stock means better performance in the paddock and higher-quality manure returning to the soil. Biochar: Long-Lasting Benefits for the Land Biochar is charcoal made from wood or crop residues in a low-oxygen environment [5]. Like humates, it has a high CEC and acts as a reservoir for nutrients and moisture. The Australia New Zealand Biochar Industry Group (ANZBIC) highlights its ability to build long-lasting soil carbon, reduce nitrate leaching, and retain nitrogen in the soil [6]. This reduces both nutrient losses to waterways and nitrous oxide emissions, tackling two of the most pressing environmental concerns for NZ agriculture. When incorporated into compost or seedbeds, biochar improves soil resilience, helping pastures survive dry conditions [7]. In small amounts, it can also be added to feed, where it binds toxins, improves gut health, and enhances manure quality [8]. Is Black Gold the Saviour? There is growing evidence that biochar, sometimes called “black gold”, can be a game-changer for worn-out soils. While not a standalone solution, used alongside balanced nutrition and good farming practice, it strengthens soil structure, builds fertility, and reduces environmental impacts [9]. Conclusion Dr Gordon Rajendram believes that solid humates and biochar offer practical, proven benefits for Kiwi farmers. By reducing nitrate leaching, lowering nitrous oxide emissions, and improving nutrient and water efficiency, they support stronger pastures, healthier animals, and more sustainable farming for the future. Key References [1] Lehmann, J., & Joseph, S. (2015). Biochar for Environmental Management. Routledge. https://doi.org/10.4324/9780203762264 [2] Stevenson, F.J. (1994). Humus Chemistry. Wiley. https://www.wiley.com/en-us/Humus+Chemistry-p-9780471594741 [3] Khan, S.A. et al. (2007). “The Myth of Nitrogen Fertilization for Soil Carbon Sequestration”. Journal of Environmental Quality. https://doi.org/10.2134/jeq2007.0099 [4] Islam, K.M.S. et al. (2005). “Use of Humic Substances in Agriculture”. Pakistan Journal of Nutrition. https://doi.org/10.3923/pjn.2005.126.134 [5] International Biochar Initiative. (2023). Biochar Basics. https://biochar-international.org/biochar/ [6] Australia New Zealand Biochar Industry Group (ANZBIC). (2024). Biochar and Soil Health. https://www.biochar.net.nz/ [7] Schmidt, H.P. et al. (2019). “Biochar in Animal Husbandry”. Agriculture. https://doi.org/10.3390/agriculture9040081 [8] Glaser, B. et al. (2002). “Ameliorating Physical and Chemical Properties of Highly Weathered Soils”. Biology and Fertility of Soils. https://doi.org/10.1007/s00374-002-0466-4 [9] Jeffery, S. et al. (2011). “A Quantitative Review of the Effects of Biochar on Soil Properties”. Agriculture, Ecosystems & Environment. https://doi.org/10.1016/j.agee.2010.09.011 Contact Dr Gordon Rajendram rajendram@xtra.co.nz 021 466 077 https://gordonrajendramsoilscientist.co.nz/ Contact MediaPA 027 458 7724 phillip@mediapa.co.nz

One of New Zealand’s leading soil scientists, Dr Gordon Rajendram, says foliar fertilisers hold the key to farmers overcoming Canterbury’s cool late winter/early spring major challenges for pasture growth. Dr Rajendram, who is based in Hamilton, says results from his research field trials have revealed  foliar fertiliser provides the necessary boost to pasture growth especially when soil temperatures are low and nitrogen uptake through the roots slow to a crawl. Foliar fertilisation involves spraying water-soluble nutrients directly onto plant leaves. It’s like a targeted nutritional top-up, allowing plants to absorb nutrients almost immediately through their foliage via stomata, cuticle and leaf hairs. “This method is proving effective in cold climates like the Canterbury region incurs,” says Dr Rajendram. “Foliar sprays deliver nutrients exactly when and where they’re needed,” he says. “You’re feeding the plant directly, so it bypasses the limitations of cold soil conditions and kickstarts growth quickly.” AgResearch Backs the Science Dr Rajendram isn’t the only one seeing these results. AgResearch, one of New Zealand’s leading agricultural science organisations, has conducted similar trials with consistent outcomes. In fact, foliar fertiliser has demonstrated efficiency rates of up to four times higher than granular applications. Faster Response, Less Fertiliser One replicated pasture trial in New Zealand revealed that just 9 kg N/ha as foliar urea achieved the same grass yield (1,426 kg DM/ha) as 37 kg N/ha of granular urea. The response is rapid for a 24 day period. That’s a powerful statistic – it means foliar N delivered about 61 kg of dry matter per kg of N, compared to just 14 kg/kg N for granular urea. “With a quicker plant response and fewer applications needed, this method saves time and product, offering real cost-efficiency to Canterbury farmers,” Dr Raendram’s trials have uncovered. Dr Rajendram notes: “Granular urea is only about 35% efficient, while foliar applications are faster and use less product overall. That’s a win for farmers and the environment.” Unit N40 (extra kg DM per unit N applied over 40 days of growth) for the different seasons and regions using Granular Urea. Reference: G.S Rajendram et al (2009). Nitrogen Fertiliser Trial Base. Taken from 1272 Nitrogen Fertiliser Response trials throughout New Zealand over 80 years conducted by MAF and AgResearch. Environmental Benefits With Canterbury’s sensitivity to nitrate leaching and water quality issues, foliar fertilisers offer an environmentally responsible choice. Because nutrients are absorbed directly by leaves rather than moving through the soil, volatilisation and there is less chance of leaching into waterways. The reduced volume of fertiliser required, further supports sustainable practices. Practical Advice for Canterbury Farmers Dr Rajendram advises farmers to use foliar sprays as a complement to their existing soil fertilisation strategies. For best results, he recommends applying in the early morning or when there is dew on the leaves – and avoiding hot, dry days to prevent leaf burn. Summary If you’re farming in Canterbury and struggling with sluggish pasture growth during late winter/early spring, foliar fertiliser may be the answer. Backed by an AgResearch study and Dr Gordon Rajendram’s decades of expertise, this method offers: By integrating foliar feeding into your nutrient management plan, you can keep your pastures thriving and your inputs low – even during the chillier months. References Contact Dr Gordon Rajendram 021 466 077 | rajendram@xtra.co.nz www.gordonrajendramsoilscientist.co.nz Contact Phillip Quay MediaPA 027 458 7724 phillip@mediapa.co.nz