BioCharge on-farm soil biology research, the programmes it supports, and how to test your own soil
BioCharge is a New Zealand-made range of liquid soil biology products built on charged Southland Carbon biochar. Rainbow & Brown is the North Island distributor.
This page brings together the on-farm research behind the BioCharge programmes: what was measured, what it showed, and what it can't tell you yet. Start with your soil test and build the programme with us.
The BioCharge range in three steps
Step 1, foundation: BioCharge Fungal Feeder
Charged biochar, fish hydrolysate and molasses. No seaweed and very little nutrient. It feeds the fungi at the heart of your soil system and is where most farms start.
Step 2, build: BioCharge Boost
The Fungal Feeder base plus a seaweed tonic to support the wider soil community. Use monitoring to decide when to move up.
Step 3, feed: BioCharge Max
N, P, K and S nutrition on the same biological base, for periods of active demand. BioCharge also makes N Boost, a higher-nitrogen option. Ask us about it.
Where it fits
| System | Target fungi : bacteria | Approach |
|---|---|---|
| Pasture and dairy | About 1:1 | Fungal Feeder, then Boost |
| Orchards, vines, berries | 2:1 to 5:1 | Fungal Feeder, K-N fertigation |
| Cropping | Crop specific | Smaller, more frequent doses |
These are BioCharge programme targets. Refine them with your own crop and soil tests.
Pasture research: what 30, 60 and 90 L/ha recorded
In spring 2026, BioCharge ran on-farm pasture research with farmer Conal Wattam. Fungal Feeder went on at 30, 60 and 90 L/ha, alongside an untreated control.
- Applied 05/09/2026
- Pasture cut 05/10/2026 (day 30) across three research areas
- Soil from Areas 1 and 2 received by Soil Foodweb NZ on 12/10/2026 (day 37)
- Every area, including the control, had the same 30 kg/ha urea product over winter
Total fungal biomass (µg/g soil, pooled soil from Areas 1 and 2)
| Treatment | Total fungi | Versus control |
|---|---|---|
| Control | 291 | - |
| 30 L/ha | 381 | +31% |
| 60 L/ha | 545 | +88% |
| 90 L/ha | 684 | +136% |
Estimated dry matter at first cut (kg DM/ha, weighted across Areas 1 to 3)
| Treatment | Dry matter | Versus control |
|---|---|---|
| Control | 1,049 | - |
| 30 L/ha | 1,346 | +28% |
| 60 L/ha | 2,025 | +93% |
| 90 L/ha | 2,050 | +95% |
Dry matter was estimated from fresh weights and a pooled dry matter percentage from Hills Laboratories.
Nitrogen-cycling potential
All three treated samples reached the lab's top reporting band of 336+ kg N/ha (a three-month estimate). The control sat at 112 to 168 kg N/ha.
Why 60 L/ha is the recommended start
90 L/ha recorded the most fungal biomass. But its first-cut dry matter was close to the 60 L/ha result. That's why BioCharge backs 60 L/ha as the kick-start rate.
Cambridge: one year of feeding the biology
On a Cambridge pasture property, soil was tested before the BioCharge programme started (spring 2025) and again about a year later (September 2026). Grazing carried on as normal.
| Sample | Total fungi (µg/g) | Fungi : bacteria | N-cycling potential (kg N/ha, 3 months) |
|---|---|---|---|
| 2025 baseline (two samples) | 136 and 127 | 0.42:1 and 0.46:1 | Under 28, and 84 to 112 |
| 2026, 30 L/ha programme (3 x 30 L/ha) | 471 | 1.38:1 | 336+ |
| 2026, 60 L/ha sample | 347 | 1.26:1 | 336+ |
| 2026, 90 L/ha sample | 389 | 1.09:1 | 336+ |
Every follow-up sample sat inside the lab's pasture range for fungi to bacteria, and above its guide for total fungi. The documented 3 x 30 L/ha programme recorded the highest total fungi and sits behind the ongoing 30 L/ha approach.
The programmes weren't set up as a timing comparison, and pasture dry matter wasn't measured at Cambridge.
What the research can and can't tell you
We want you to see these numbers for what they are. They're early on-farm results, and they're encouraging. They're not proof that BioCharge will do the same on your farm.
- There's one pooled soil result per rate and no statistical testing.
- Starting pasture cover wasn't measured in the pasture research, and soil varies across any paddock.
- The soil and harvest results cover different area sets, so they don't line up plot for plot.
- The 336+ figure is a lab estimate of nitrogen-cycling potential over three months. It isn't measured nitrogen release and shouldn't be counted as a fertiliser credit.
- Active fungi rose but stayed below the lab's reference levels in both studies.
- Cambridge had no untreated area for comparison, and other inputs, weather and grazing weren't isolated.
Further cuts and testing are under way, and we'll update this page as results come in. The best evidence for your farm is your own before-and-after soil test.
How we'd suggest starting
Year one: kick-start and maintain
Start with 60 L/ha of Fungal Feeder, then apply two separate 30 L/ha maintenance doses later in the year. 60 + 30 + 30 = 120 L/ha.
Ongoing: 3 x 30 L/ha each year
Keep feeding the biology with 30 L/ha in spring, summer and autumn, timed to soil conditions. 3 x 30 = 90 L/ha a year.
A 1,000 L IBC of Fungal Feeder covers about 8.3 ha in the kick-start year, or about 11.1 ha a year at the ongoing rate.
Test before and after
We recommend a Soil Foodweb fungi to bacteria test before you start and again after. Ask us about a test-cost rebate when you order.
Specialist horticulture: custom brews
BioCharge also makes custom products for orchards and horticulture. These are made to order and priced on application, so they aren't listed online. Talk to us if one of these fits your operation:
- Orchard Canopy Spray: a custom foliar brew tailored to the crop, growth stage and nutrient needs. BioCharge agrees the formulation, rate, dilution and timing for each programme.
- K-N Fertigation Blend: custom root-zone nutrition through suitable irrigation systems.
- Fungal Protect: a bespoke seaweed-based foliar product with amino acids.
Read the full research
BioCharge has published the full results, graphs and methods:
Start with your soil test. Build the programme with us.
Call Ryan Kidd, Sales & Operations, on 021 529 485 or 0508 299 299, or email ryan@rainbowbrown.co.nz.
