Brian Schnell’s phone call

“Here’s the problem I was having. My pond was crusted over and I was losing holding capacity. Not only that, the solids were constantly blocking the irrigation jets, which was a major pain.”

Brian had had these problems before and had paid contractors to come in and stir the pond and suck out the solids. He even had a digger brought in to excavate the crust. But the crust always came back.

“Then I saw the Slurry Bugs advert, about good bacteria that liquefy the pond by eating the crust. So, I called David Law and said, ‘I need my effluent pond fixed. Can your Slurry Bugs do the job or do I need more mechanical solutions?’ He told me not to spend another cent on machines.”

Pond crust 2

Three things David noticed

David drove from Hamilton to inspect Brian’s pond. Within 10 minutes, he noticed three things.

“The most obvious was the thickness of the crust: 15cm. Then I looked for bubbles. Bubbles are a sign that good aerobic microbes are at work, eating crust and liquefying the pond. I saw no bubbles at all.

“I could also see green coloration around the pond. That green colour occurs when Chlorine kills micro-organisms. That explained the absence of crust-eating bacteria.”

Slurry Bugs can fix this pond

The first thing David explained to Brian was that bad microbes (pathogens) were the cause of the effluent solids. These bacteria hate light and oxygen and create a light-blocking lid by separating the effluent fibres and sending them to the pond surface (crust). They also send fibres to the floor (sludge).

But Slurry Bugs are aerobic.

“Slurry Bugs need oxygen and light. To survive, they eat the crust to let light and oxygen break through. After Slurry Bugs eat the crust, they then excrete the solids in a liquefied form.

“But more than that, their digestive systems change the composition of the pond nutrients – from unstable to stable organic forms that plants can easily use.

“So now you have effluent that is easily pumped and is a far better fertiliser.”

Brian, do these three things

David asked Brian to do three important things:

1. Change the atmosphere of the pond so Slurry Bugs can multiply and work effectively.
2. Add a booster of Slurry Bugs into the pond.
3. Keep chlorine chemicals out of the pond by using an alternative sanitising product.

2 months later: almost no crust

Brian carried out David’s instructions and within two months, good biological activity was present and the crust had significantly decreased. Brian was delighted with how Slurry Bugs were performing.

clear pond 2

“Now, let’s fix your farm”

David then told Brian the deeper truth about pond crust: that the state of his pond was merely symptomatic of a nutrient imbalance in his soil.

“I told Brian that the crust on his pond is undigested feed and that undigested feed is directly related to the low pH in the rumen of his cows. Low pH is an environment that stunts the work and reproduction of good, digesting organisms.

“The state of a cow’s rumen is directly related to the nutrient imbalance in the feed, which is directly related to an imbalance in the soil. It’s all about the soil.”

Introducing the BioCircle

David sees every farm as a BioCircle of transference. What’s in the soil goes into the grass. What’s in the grass goes into the cow. What’s in the cow goes into the effluent pond. Everything, whether good or bad, gets transferred.


  • Nutrients get transferred: balanced or imbalanced
  • Organisms get transferred: beneficial & harmful
  • pH levels get transferred: acidic or neutral

The soil is the start of everything

To solve the root-cause of pond crust (and poor animal health and low milk production), farmers need to focus on soil conditions. If the soil conditions are right, everything else will fall into line, like dominos.

So, what are the ‘right’ soil conditions?

A balanced pH of 6.4

David describes soil as follows.

“Farmers should think of their soil as a grass-growing factory. That factory is filled with trillions of workers – the micro-organisms that live there. These guys are the ones who grow the grass.
They transport nutrients to the plants, and in the right forms. They increase nutrient retention. They release hormones that stimulate root growth. They detoxify soil and suppress plant diseases. They improve the soil’s stability, porosity, and moisture-holding capacity. They organise soil structure which helps air and water flow.

“You cannot overstate their importance for grass growth.

“The reason why a pH of 6.4 is crucial is because that’s the environment these good microbes prefer. 6.4 enables them to work efficiently and to multiply. BUT, you have to get 6.4 through a good balance of a range of nutrients, not just by adding lime.”

The problem with many soils

David has soil-tested hundreds of farms. The most common problem he finds is a pH that is too low due to an imbalance of the 16 key nutrients. This low pH has a double-blow effect:

1. Low pH stunts the work of good organisms
2. Low pH helps disease-causing pathogens

The problem with Brian’s soil

Forward Farming carried out a soil test (tested in Missouri, USA). Even though the test revealed Brian’s soil had an ideal pH of 6.4, it was achieved through an imbalance of the four elements that influence pH – Calcium, Magnesium, Potassium, and Sodium.

Brian’s soil Magnesium was too high in relation to Calcium levels and this was having a negative effect on soil enzymes. Tests also revealed that the organic matter, which feeds soil biology, was too low.

How we fixed Brian’s soil

First, we added lime at 625kg/ha to get Brian’s Calcium levels up to 68%. Increasing Calcium by the correct amount automatically reduced Magnesium to the ideal range in relation to Calcium.

To increase organic matter, 240kg/ha of compost was added to the fertiliser mix. Phosphate was not added because it was already within an acceptable range.

The results on Brian’s farm?

1. Better grass growth + greater biological activity

2. Cases of mastitis down from 25 to 3

3. Cases of lameness down from 15 to 2

4. Milk Urea down 39% from 29.44 to 18.11*

5. More efficient nitrogen fixation = almost no artificial N required

6. Pond remains liquefied: no further Slurry Bugs added

*October 2015 compared to October 2016

To read more:
To contact David: 027 490 9896

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