Back in June 2025, we wrote about urea volatility and the role biological inputs could play in reducing reliance on synthetic fertiliser.
Less than a year on, that conversation has shifted from “emerging risk” to current reality.
Ongoing conflict in the Middle East - particularly disruption through the Strait of Hormuz - is now materially affecting global fertiliser and fuel supply. That matters because:
At the same time, fuel costs are climbing - compounding the cost of producing, transporting, and applying fertiliser.
This isn’t just a price issue. It’s a systems issue.
Nitrogen fertiliser (like urea) is tightly linked to energy markets.
That’s why global events - whether it’s war, gas shortages, or export restrictions - tend to hit nitrogen hardest.
The knock-on effect is already visible globally:
For most New Zealand farmers, the challenge isn’t whether to use fertiliser, it’s how to use it more efficiently under pressure.
When inputs become expensive or uncertain, there are only a few levers available:
That third option is where soil condition and biology start to matter more.
There’s been growing interest in soil conditioners and biological products but it’s worth being clear about what they can and can’t do.
They are not direct substitutes for fertiliser. Most don’t supply nutrients in the same quantities.
Based on a growing body of research, what they can do is support the efficiency of nutrient use by influencing:
Different products approach this in different ways.
Compost
Adds organic matter and improves soil structure and moisture retention.
Well supported by research for long-term soil health but nutrient release is slow, and large volumes are typically required to shift fertility.
Humates (humic & fulvic substances)
Can improve nutrient availability and root growth in some systems.
Evidence shows variable responses depending on soil type, crop, and existing organic matter levels, so results aren’t always consistent.
Seaweed extracts
Often used to support plant stress tolerance (e.g. drought or cold).
Generally act more as plant biostimulants than soil builders.
Microbial inoculants
Introduce specific beneficial microbes.
Can be effective in controlled conditions, but field performance can be inconsistent - particularly where soils already contain established microbial communities.
Vermicast (worm castings)
Vermicast is positioned slightly differently because it combines:
Peer-reviewed studies have shown vermicast can:
However, responses vary depending on soil type, climate, and application rate - as with any input.
The key point isn’t that biological inputs replace fertiliser.
It’s that they can influence how efficiently fertiliser performs in the system.
Mechanisms that are supported in the literature include:
In practical terms, that can mean:
But outcomes are system-dependent and should be validated on-farm where possible.
The key takeaway from the past 12 months is that fertiliser supply and pricing are no longer stable background assumptions.
They are strategic risks.
Even if supply improves in the short term, the underlying drivers - energy dependence, geopolitics, and global trade concentration - aren’t going away.
So the question isn’t whether to use fertiliser.
It’s how to build systems that are:
Biological inputs - including vermicast - won’t solve that on their own.
But as part of a wider approach, they are increasingly being considered - not as a replacement, but as a way to get more from what’s already being applied.
If you'd like to try vermicast to get more out of your fertiliser get in touch - we'd love to hear from you.