“The solution is a combination of using less fertiliser and also using better science to apply only what is truly needed,” Dr Rajendram said today.

A crucial starting point is soil and pasture testing. Dr Rajendram consistently emphasises that without accurate data, fertiliser programmes become guesswork.

“Comprehensive testing identifies nutrient deficiencies, soil pH, and retention capacity, allowing farmers to apply inputs precisely rather than broadly,” he says.

“This avoids over-application, which not only wastes money but can also lead to nutrient losses through leaching. In fact, testing is considered one of the most cost-effective steps in nutrient management, often representing a very small proportion of overall fertiliser spend while delivering significant savings,” Dr Rajendram said.

Beyond testing, there is growing evidence that many farms are applying more nutrients than required, particularly phosphate.

Dr Rajendram notes that some New Zealand soils can retain phosphate for several years, meaning annual applications are not always necessary. Shifting away from routine fertiliser programmes to a needs-based approach can significantly cut costs without impacting production.

“Nitrogen use is another area where efficiency gains can be substantial” he says.

“Rather than relying heavily on granular applications, more farmers are adopting targeted methods such as foliar spraying. This approach delivers nutrients directly to the plant, improving uptake and reducing the total amount required. Trials have shown that significantly lower nitrogen rates can achieve comparable pasture growth when applied in this way, highlighting a clear opportunity to reduce input costs.”

Soil condition itself also plays a major role. Maintaining optimal pH through liming improves nutrient availability and root development, meaning plants can access more of the nutrients already in the soil. Poor pH, on the other hand, limits growth and reduces fertiliser efficiency, effectively increasing the cost per unit of production.

While reducing synthetic inputs is important, Dr Rajendram also advocates for strengthening biological systems within the pasture. Clover remains a critical component, naturally fixing nitrogen from the atmosphere and reducing reliance on purchased fertiliser. However, he stresses that clover should be part of a broader, balanced system that includes diverse pasture species and well-managed soils. Excessive nitrogen use can actually suppress clover’s ability to fix nitrogen, reinforcing the need for moderation and balance.

“Ultimately, the shift is about moving from a fertiliser-driven system to a soil-driven one,” Dr Rajendram said.

As Dr Rajendram states: “Farmers are increasingly recognising that they may not need as much fertiliser as once thought. By combining accurate testing, targeted application, improved soil management, and biological inputs like clover, farmers can reduce costs, maintain productivity, and build more resilient farming systems in the face of ongoing global price pressures.”

About Dr Gordon Rajendram:

With more than three decades of experience in soil fertility, Dr Rajendram’s approach centres on improving efficiency, reducing waste, and unlocking the natural potential already present in the soil.

For more information, please contact:

Contact Dr Gordon Rajendram

021 466077

rajendram@xtra.co.nz

www.gordonrajendramsoilscientist.co.nz

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The post Leading Hamilton Soil Scientist Dr Gordon Rajendram Urges Smarter Soil Science By New Zealand Farmers To Offset Spike In Global Fertiliser Costs first appeared on Gordon Rajendram the soil scientist.

Global conflict is once again exposing just how vulnerable New Zealand farming systems are to international supply chains. Rising fuel prices, disrupted shipping routes, and instability in key fertiliser-producing regions are driving up the cost of transport and nitrogen fertilisers such as urea. These are costs farmers cannot control, yet they directly impact farm profitability.

We have been here before. The difference now is that we have better knowledge and proven systems that show we do not need to rely so heavily on imported nitrogen.

A Canterbury case study I was involved in clearly demonstrated this. A large-scale dairy operation reduced nitrogen inputs from 290–300 kg N/ha/year down to under 190 kg N/ha/year, while also cutting phosphate use from 45 kg/ha to 15 kg/ha annually. At the same time, pasture production still reached up to 19 tonnes of dry matter per hectare and milk production wasn’t compromised.

The key was not applying more fertiliser, but improving soil pH and soil biology, nutrient balance, and clover performance.

Clover is central to this discussion. It is not just another pasture species, it is a natural nitrogen factory. Research has shown white clover can fix anywhere from 20 kg to as much as 400 kg N/ha/year in grazed systems, but under ideal conditions, 250-350 kg consistently is possible and even higher. That nitrogen is effectively free, produced in the paddock, and available to drive pasture growth without the cost of urea.

At the same time, clover is one of the highest-quality feeds available. With protein levels of around 34 percent compared to approximately 19 percent in ryegrass, it delivers significantly more nutritional value to livestock. Higher energy, higher protein, and better mineral content, including calcium, all contribute to improved animal performance.

“One of the first things I look at is what the pasture looks like and how much white clover is in it.”

This translates directly into production. Research consistently shows higher liveweight gain and increased milk yield from cows grazing clover-rich pastures due to higher intake and better feed efficiency. Simply put, more clover means more milk.

However, excessive nitrogen fertiliser works against this system. Once nitrogen applications exceed around 200 kg N/ha/year, clover fixation declines sharply, and at very high rates it can stop altogether. Farmers then become locked into a cycle of dependency on purchased fertiliser, exactly the risk we are seeing play out today with global price volatility.

As I often say, “The more nitrogen you grow biologically through clover, the less you need to buy, and the more resilient your farming system becomes.”

The message is clear. In a world of rising costs and uncertainty, clover offers a proven pathway to reduce input costs, improve pasture quality, and lift milk production. It fixes the nitrogen problem naturally, efficiently, and economically.

Global events may be out of our control, but how we manage our soils and pastures is not.

“Any fool can grow rye glass but it takes a real farmer to grow clover.” – Emeritus Professor Walker

For more information, contact:
Dr Gordon Rajendram
📞 021 466077
✉️ rajendram@xtra.co.nz
🌐 www.gordonrajendramsoilscientist.co.nz

Media Enquiries:
Media PA – Phillip
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The post Dr Gordon Rajendram: War, Crisis and Why Clover Matters More Than Ever first appeared on Gordon Rajendram the soil scientist.

Pictured above: Caption to depict the role of Biochar, Humates and Microorganisms to reduce Nitrate leaching

In the previous article, I discussed the role of humates, biochar, plant roots and foliar strategies in slowing nitrogen movement through the soil. Building on that foundation, it is useful to look more closely at the research behind carbon-driven nitrogen retention and why these tools are gaining increasing attention within New Zealand farming systems.

Biochar has been investigated across a range of agronomic settings for its capacity to alter nitrogen dynamics. Its porous structure and surface charge characteristics increase sorption capacity, improve microbial habitat, and moderate nutrient movement through the soil profile. Controlled trials have demonstrated measurable impacts on nitrate mobility. For example, research published in Agronomy reported that incorporating biochar at approximately 10% by volume prevented detectable nitrogen leaching under experimental conditions, highlighting its capacity to physically and chemically retain nitrogen in the root zone rather than allowing downward migration.

Further work examining “bioactive carbon” amendments has reinforced this functional outcome. Studies evaluating nitrogen fertiliser efficiency and ecological sustainability observed improvements in nitrogen use efficiency alongside reductions in environmental losses. These findings align with the broader international literature and complement observations made in New Zealand soil science research, where carbon additions influence microbial immobilisation pathways and nitrogen cycling behaviour.

Humates, particularly in solid form, have also shown significant promise as a food source for microbes. Their complex organic structure supports cation exchange capacity, microbial activity, and nutrient buffering. Reported trial data indicate reductions of up to 60% in nitrate leaching when solid humate materials were integrated into fertiliser strategies. Such results are consistent with the theoretical framework long outlined by soil scientists, including Hedley and colleagues, where organic matter fractions regulate nutrient retention through chemical binding and biological mediation.

It is important to emphasise that these tools are not substitutes for sound nutrient management planning. They function best when integrated with appropriate fertiliser timing, application rates, and soil monitoring.

A brief note should also be made regarding pure sucrose. While not a retention agent in the structural sense, carbon supplementation through simple sugars can stimulate microbial uptake of available nitrogen, temporarily immobilising nitrate within microbial biomass. This mechanism has been explored within nitrogen cycling research and can contribute to reduced short-term losses when used strategically.

Taken together, the emerging research evidence indicates that carbon-based amendments can play a meaningful role in addressing nitrogen leakage pathways. For farmers facing increasing environmental accountability and regulatory pressure, these tools deserve consideration not as silver bullets, but as practical components within a broader nutrient stewardship strategy.

Contact Dr Gordon Rajendram

021 466 077 | rajendram@xtra.co.nz

www.gordonrajendramsoilscientist.co.nz

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The post Leading Hamilton Soil Scientist Dr Gordon Rajendram Digs Deeper into Biochar & Humates as an Environmental Saviour for Canterbury Farmers first appeared on Gordon Rajendram the soil scientist.

One option I often work with is the use of solid humates. Humates act primarily as a carbon source for soil microbes. When microbes have adequate carbon, they become more active and are able to temporarily hold nitrogen within their biomass. This slows down the conversion of nitrogen into nitrate and reduces the speed at which it moves through the soil profile. The key point is that nitrogen is still available to plants, but it is released more gradually.

Biochar works in a different but complementary way. Rather than acting mainly as a food source, biochar provides physical structure in the soil. It creates protected spaces where microbes can live and function more effectively, particularly under stress. At the same time, both biochar and humates have the ability to hold onto nutrients, including nitrogen, helping to keep them in the root zone instead of allowing them to leach. Used together, they support a more stable soil system where nitrogen is retained for longer periods.

Plant roots are another important part of the picture. Typical ryegrass roots extend to around 20 to 30 centimetres. There is a lot of nutrients lost during leaching, and in dollar terms, this could be as much as half or more of what you apply in a year as fertiliser. Deeper-rooting species can intercept nutrients that move further down the soil profile, capturing nitrogen before it is lost below the root zone. Encouraging deeper and more diverse root systems adds another layer of protection against nitrate leaching.

Foliar application is also a useful tool in this toolbox. By supplying nutrients directly to the plant through the leaf, foliar feeding can improve nutrient efficiency and reduce the reliance on soil-applied nitrogen. When plants are better balanced nutritionally, they use nitrogen more effectively, which means less excess nitrogen remains in the soil to be leached.

In Canterbury, I will soon be measuring the effectiveness of these systems more precisely using lysimeters to better understand where the nitrogen is going and how effectively it is being retained.

The key takeaway is that reducing nitrate leaching requires a toolbox, not a single solution. By combining management changes with carbon inputs, plant strategies and targeted foliar nutrition, farmers can significantly reduce losses while maintaining productive and economically viable systems.

Contact Dr Gordon Rajendram

021 466 077 | rajendram@xtra.co.nz

www.gordonrajendramsoilscientist.co.nz

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The post Ways to Reduce Nitrate Leaching, Part 2, with Leading NZ Soil Scientist Dr Gordon Rajendram first appeared on Gordon Rajendram the soil scientist.

In the previous article, I outlined why nitrate leaching occurs and why it is so difficult to control. Now, I will look at some of the practical options that can help reduce losses. These are not silver bullets, and they are not all suitable for every farm, but each can play a role.

One option is to reduce cow numbers. From a purely scientific point of view, fewer cows mean less nitrogen entering the system, and therefore less nitrate leaching. However, I need to be very clear that simply reducing stocking rates is usually not economically viable on its own. Without major system changes, farm income often drops to a point where the business becomes unsustainable. It may reduce leaching, but it is not a realistic standalone strategy for most farmers.

Pasture typically contains 3% nitrogen (approximately 18% protein). If you apply nitrogen fertiliser, these levels can get up to 5.5%, and the excess N gets excreted by the animal.

This work of mine showed that the amounts of nitrate-N, calcium leaching went up with increasing rates of N applied at DRC No. 2 dairy during 1996.

The key takeaway here is: The less nitrogen applied, the less nitrate leached.

Another option is keeping cows off pasture for part of the day using feed pads. Urine patches are one of the biggest drivers of nitrate loss. A 500-kilogram cow can excrete close to 10% of its body weight each day, which equates to around 50 kilograms of dung and urine. If cows are kept off pasture for roughly a third of the day, nitrate leaching from urine patches can be reduced significantly. Whilst this can result in large reductions in nitrate loss, it does come with costs such as infrastructure, additional management time and feed handling. It is an effective tool, but it must be carefully considered.

Diet also plays an important role. The key point here is that feeding more carbohydrates reduces the amount of nitrogen excreted in urine. Supplements such as grain or palm kernel are lower in nitrogen. If you substitute more carbohydrates for pasture, the total nitrogen entering a cow’s system is lowered. This dilution effect means less excess nitrogen is excreted in urine and less nitrate is available to leach.

All of these options show that nitrate leaching can be influenced through management changes. In the Canterbury region, I am working with a farmer using a combination of these approaches, and the measured nitrate losses are very low. In the next article, I will focus on soil and plant-based tools that can be used alongside these management strategies to further reduce nitrate leaching.

The post Ways to Reduce Nitrate Leaching Part 1 first appeared on Gordon Rajendram the soil scientist.

In this first article, I want to focus on one of the most pressing issues affecting both productivity and the environment: nitrate leaching. This problem has been developing for decades, yet many of the underlying mechanisms are still not well understood by the wider farming community. Before we can consider ways to reduce losses, we need to understand what is happening in the soil.

The starting point is soil chemistry. Soil particles carry a natural negative charge. Positively charged ions such as calcium, magnesium, sodium and potassium are attracted to the soil surface and remain in the root zone where plants can access them.

Because nitrate is also negatively charged and like charges repel, nitrate is not held by the soil in the same way, leading to leaching if not used by the plants. Once nitrogen in the soil is converted into nitrate, it can move through the soil profile whenever water is present, and once past the root zone, it’s pretty well gone. Rainfall and irrigation drive this movement downward, eventually carrying nitrate into groundwater or surface water.

This process is particularly problematic in pastoral systems because of the way nitrogen is deposited in urine patches. When livestock urinate, the concentration of nitrogen in that small area is far higher than plants can use. Because the volume of urine creates a significant water load, the nitrate begins its downward movement almost immediately.

The scale of loss varies with soil type, rainfall, stocking rate and management. This is not a question of poor farming practice. It is simply the reality of how nitrogen behaves in our soils. Nitrate that is lost from the root zone cannot contribute to pasture growth; it represents a wasted nutrient, lost productivity and increased input costs. At the same time, nitrate accumulation in waterways poses well-known environmental risks.

There are practical ways to reduce these losses, but we need a clear grounding in the science before exploring them. In my next article, I will discuss some solutions, so farmers can start to learn about what will work best on their land.

The post Understanding The Causes And Effects Of The Serious Issue Of Nitrate Leaching first appeared on Gordon Rajendram the soil scientist.

By incorporating carbon rich amendments such as humates and biochar, Dr Rajendram explains, farmers can shift nitrogen into more stable forms. Carbon inputs strengthen microbial immobilisation, essentially giving soil microbes something to feed on so that nitrogen stays bound in organic forms rather than rapidly converting to nitrate. The effect is twofold: less nitrate escapes into groundwater, and more nitrogen remains available for plant uptake, boosting productivity.

International research strongly supports this route. For instance, meta analysis work shows that biochar applications cut nitrous oxide emissions by around 54 percent on average. Lysimeter trials in New Zealand have gone further, recording reductions in nitrate leaching of 75 percent or more under ryegrass and clover systems when significant carbon amendments were applied. Dr Rajendram thus argues the challenge is not only finding the right products, but calibrating them for farm scale practicality: frequency, rate, and integration with grazing and fertiliser regimes.

He counsels farmers to view soil carbon amendments as part of a broader system change. For example, pairing humates at around 10 kg/ha with each fertiliser pass, currently being trialled by some Taupō area dairy farms, is one promising model. Over time the build up of stable carbon enhances the soil’s sink capacity for nitrogen, making the system more resilient under high stocking and fertiliser loads.

Dr Rajendram notes that this is just one effective strategy among several available to address nitrogen leaching. Different farm systems and soil types may require varied combinations of approaches, including changes to grazing management, fertiliser timing, and the introduction of cover crops or alternative pasture species.

For farmers facing regulatory constraints, this science based approach offers a pathway that is both sustainable and productive. As Dr Rajendram says: “We can trap more nitrogen in the soil where plants can use it, or let microbes convert it harmlessly to N₂, rather than losing it to waterways.” The shift, he insists, will require better measurement, smarter amendments and a willingness to think long term. The payoff? Lower environmental footprint and improved nutrient efficiency, a win for farm profitability and catchment health alike.

For more information and references, visit gordonrajendramsoilscientist.co.nz.

References

1. Manaaki Whenua – Landcare Research. Carbon inputs to reduce nitrogen losses from farms. Link
2. Qin, S. et al. Denitrification and DOC effects. ScienceDirect. Link
3. Lincoln University / Landcare Research archive. Increasing the available C supply from plant roots reduces nitrification potential in soils. Link

Contact Dr Gordon Rajendram

021 466 077 | rajendram@xtra.co.nz

www.gordonrajendramsoilscientist.co.nz

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The post Cutting Nitrate Leaching the Smart Way: Dr Gordon Rajendram’s Carbon Strategy first appeared on Gordon Rajendram the soil scientist.

Leading Hamilton-based soil scientist Dr Gordon Rajendram says nitrate leaching has become one of the most critical current challenges for pastoral farms across New Zealand threatening both water quality and environmental sustainability.

And he has the backing of a growing number of farmers who are putting into practice his advice.

“In grazed pastures, urine patches from livestock are the primary culprit: they supply nitrogen far in excess of plant demand, making the surplus vulnerable to leaching as nitrate,” says Dr Rajendram, who is at the forefront of promoting practical, research-based solutions to alraming issue.

In Gore, Southland, rising nitrate concentrations in the town’s water supply have raised concern among residents, while further north, Environment Canterbury (ECan) is facing growing public pressure to address nitrate contamination across parts of Canterbury’s groundwater network. These are not isolated issues; they’re unfolding in different regions across New Zealand, affecting both farmers and communities alike.

Why Carbon Makes a Difference

Adding carbon to soils, through humates, biochar or other organic sources, helps retain nitrogen in forms that plants and microbes can use, rather than allowing it to convert into mobile nitrate. Carbon inputs stimulate microbial immobilisation of nitrogen, slow nitrification (the conversion of ammonium to nitrate), and support denitrification processes that convert nitrate into benign dinitrogen (N₂).

Biochar, sometimes nicknamed “black gold”, has attracted considerable scientific attention. Made from plant material under low-oxygen pyrolysis, it acts like a sponge in the soil, holding water and nutrients and altering microbial activity. In a recent study (Clough et al., 2020) published in Soil Biology and Biochemistry, Professor Tim Clough and colleagues demonstrated that when biochar or carbon-rich amendments comprised a high fraction of soil volume, nitrate losses were dramatically curtailed. That research supports the notion that around 10% by volume biochar (relative to soil) can very significantly reduce nitrate leaching, reinforcing the promise of high-carbon strategies.

Another meta-analysis of 30+ studies (Cayuela et al., 2014) showed that biochar reduces emissions of nitrous oxide (N₂O) by an average of 54%, with stronger effects for higher-quality biochars and optimal application methods.

Humates are yet another valuable tool. These naturally occurring substances enhance soil structure, stimulate microbial life, and boost the soil’s capacity to retain nutrients and moisture. Trials reported in Farmers Weekly found that humates applied with urea increased pasture yield by up to 30% while reducing nitrogen losses. Long-term trials led by Dr Peter Espie showed nitrogen leaching reductions of around 61% and pasture gains up to 11% over ten years.

Supporting Research Findings

• Landcare Research (Manaaki Whenua) lysimeter trials showed that carbon applications can significantly reduce nitrate leaching, with results indicating reductions of around 75 percent under ryegrass and white clover, 51 percent under lucerne, and up to 91 percent at higher rates. While large amounts achieved the greatest effect, the key is applying smaller quantities more frequently for sustainable results. Carbon helps tie up nitrogen in the soil, preventing it from leaching away while supporting healthy plant growth.

• Dr Gordon Rajendram has carried out extensive work on nitrate leaching and knows what is required to achieve meaningful reductions. Pure carbon is one of several proven solutions, and the right approach can substantially cut leaching without reducing stock numbers. With increasing regulatory pressure in areas where nitrate levels are rising, Gordon can help farmers identify practical and effective ways to restore soil balance and maintain productivity.

• A ScienceDirect study (Qin et al.) found that with ample dissolved organic carbon (DOC), nitrate is preferentially denitrified to N₂ rather than nitrous oxide.
• Research from Lincoln University and Landcare Research showed that increasing the available carbon supply reduces nitrification potential in soils, thereby lowering nitrate formation and leaching.

Together, these findings show that adding sufficient carbon, through humates, biochar or other organic sources, can dramatically cut nitrate leaching, even from intense urine patches.

Expert Insight

Dr Rajendram emphasises: “By pairing carbon-rich amendments with strategic farm management, we can trap more nitrogen in the soil where plants can use it, or let microbes convert it harmlessly to N₂, rather than losing it to waterways. This is about giving farmers workable solutions, not criticism.”

What This Means for Farmers

Farmers are suppporting Dr Rajendram’s ground-breaking scientific approach in growing numbers and noticing marked differences from adopting his advice.

Dr Rajendram has been consulting to Taupo dairy farmer Mark Robertson for about six years.

“Dr Rajendram’s recommendation was to apply humates every time I used my tow n fert machine at approx solid fine ground humates 10kg per hecate with a cost of around $7 per hectare and I have applied approximately 150kg per hectare of humates to date,” Robertson said.

“The aim is to build carbon levels with humates or biochar to bind up as much urinary Nitrogen as possible and the results are heading in the right direction,” Robertson said.

“Dr Rajendram is a leader soil health and his input is very important to the growth of pasture. It is the right time for a changed approach in terms of what we are looking at for the future,” Robertson said.

Northland farmer Michael Mackinven is feeding biochar to cows and has confidence it is the right approach to take.

“Dr Rajendram is an absolute expert in his field of soil health and provides very high level advice. We are very fortunate to have him and the wealth of knowledge he brings to our industry,”  Mackinven says.

“Dr Rajendram  has been on the farm taking soil tests and giving his expertise to help us work out the best products such as humates and fish and the evidence we have seen with the topsoil development is positive,” Mackinven said.

“I have total confidence in his judgement and his years of experience stand him in good stead,” MacKinven said.

“For farmers, this is a practical and science-backed path forward. By adopting carbon-based amendments such as humates and biochar, they can reduce nitrate leaching, improve nutrient efficiency, and safeguard waterways-all while maintaining profitable production. As Dr Gordon Rajendram, leading New Zealand soil scientist, highlights, these strategies combine productivity with sustainability, protecting both farms and the environment and we are taking his guidance with his years of experience standing him in good stead,” MacKinven said.

References

1. Ministry for Primary Industries (MPI) (2018). N₂O and ammonia emissions from biochar-amended urea prills. Link
2. Farmers Weekly (2022). Benefits of soil humates highlighted. Link
3. Otago Daily Times (2023). Stimulant raised growth in 10-year trial. Link
4. Clough, T. J., et al. (2020). Soil carbon fractions influence nitrous oxide emissions following urine deposition. Soil Biology and Biochemistry, Elsevier. Link
5. Cayuela, M. L., et al. (2014). Biochar’s role in mitigating soil nitrous oxide emissions: A review and meta-analysis. Agriculture, Ecosystems & Environment, Elsevier. Link
6. Manaaki Whenua – Landcare Research. Carbon inputs to reduce nitrogen losses from farms.
7. Qin, S. et al. Denitrification and DOC effects. ScienceDirect.
8. Lincoln University / Landcare Research Archive. Increasing the available C supply from plant roots reduces nitrification potential in soils.

Contact Dr Gordon Rajendram

021 466 077 | rajendram@xtra.co.nz

www.gordonrajendramsoilscientist.co.nz

Contact MediaPA

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The post Leading New Zealand Soil Scientist Dr Gordon Rajendram – An Expert On Humates, Biochar and Carbon – Calls For A More Scientific Strategy To Slash Nitrate Leaching first appeared on Gordon Rajendram the soil scientist.

Dr Rajendram’s  field trials for a number of companies aim to bring Kiwi farmers new ways to improve soil health, boost crop performance, and cut down on nutrient losses.

During his 22 years at AgResearch and Ruakura Research Centre he developed two field calibrated soil tests and much of his research and development has been applied to the agriculture industry with excellent results.

He has more than 70 publications and six patents to his name and is independent consultant to farmers and fertiliser companies to whom he is committed to getting the most out of their soil so that the farm can work more proficiently, be sustainable whilst still increasing farm profitability.

With Dr Rajendram’s expert hands-on experience in farm systems and BPM’s natural zeolite products, the field trials will focus on practical solutions that make a difference in the paddock.

BPM’s zeolite is mined in the Waikato and is known for its ability to hold on to both water and nutrients. It acts a bit like a sponge, soaking up moisture and fertiliser and then releasing them back to the plant when needed. This means fewer nutrients are lost through leaching, and pastures and crops can keep growing even when conditions get tough. Farmers using zeolite have found it helps lift production while also supporting long-term soil health.

Alongside this, Dr Rajendram is highlighting the value of foliar application. Instead of relying only on fertiliser going into the soil, foliar feeding applies nutrients directly to the leaves, where they are quickly absorbed. This method is especially useful when soil conditions slow down uptake, such as in cold or dry weather, or during key growth stages when plants need an extra boost. Applying trace elements like zinc, copper, or boron through foliar sprays can give crops what they need straight away, improving growth and resilience.

BPM’s zeolite and foliar application gives farmers a smarter way to manage nutrients. Zeolite holds fertiliser in the soil for steady release, while foliar sprays top plants up at the right time. This reduces waste, keeps nutrients where they belong, and helps drive better yields.

Dr Rajendram says the goal is simple: “Farmers don’t need more fertiliser; they need nutrients working harder for them. By using the right products in the right way, we can save costs, protect the environment, and grow stronger crops.”

For more information, contact:
Dr Gordon Rajendram
📞 021 466077
✉️ rajendram@xtra.co.nz
🌐 www.gordonrajendramsoilscientist.co.nz

Media Enquiries:
Media PA – Phillip
📞 027 458 7724
✉️ phillip@mediapa.co.nz

The post Leading New Zealand Soil Scientist Dr Gordon Rajendram and Blue Pacific Minerals: Helping Farmers Get More from Foliar Application first appeared on Gordon Rajendram the soil scientist.

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

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phillip@mediapa.co.nz

The post Is Black Gold the Saviour for NZ Agriculture? – Dr Gordon Rajendram on the Promise of Biochar and Humates first appeared on Gordon Rajendram the soil scientist.