Brix Barometer

Brix (%) is a measure of the light refracting through dissolved solids & sugars with the use of a portable refractometer, and is a useful and quick indication of the health of your plant sample.

The Brix Barometer is a combined metric monitored & benchmarked on the Regen Platform, telling you the difference between the brix reading of weeds on your farm, with the brix of your grasses or crops. If your weeds have a higher brix than your desirables, this indicates your soil needs some support! If the weeds have a lower brix than your crops, you don’t need to intervene – your crops will outcompete the weeds in time.

Brix levels fluctuate throughout the day, generally peaking in the afternoon before dropping at night. Brix levels will also vary due to stress or deydration, so this is a metric you can continue to record regularly throughout the year, to keep a good record of how things are changing. The ‘fuzziness’ of the line you read through the refractometer is an indicator of how nutrient dense the sample is – a sharp line can indicate calcium deficiency for example. A low brix reading indicates your plant is vulnerable to pest attack, and has high nitrate levels (which works against nutrient density & complexity).

What to record

  • Two separate brix readings: weeds & grass or crops
  • Number 0-30 on ‘Brix’ scale of refractometer
  • Note of whether the line is fuzzy or not
  • Photos


  • Refractometer (0-32%)
  • Heavy duty Garlic Crusher
  • Water Squirt Bottle (optional)
  • Dry cloth/kitchen roll
Find links to buy equipment below…

How to do the test

1. This test can be done alongside your basal ground cover transect. Moving along approximately the first 10m of your transect away from your sample site, collect a handful of plant material by tearing – like a cow or a sheep munching at the plants.
N.B: Do not sample diseased, insect attacked or stressed plants.

2. Collect two separate measurements for ‘Brix of grass or crops (%)’, and ‘Brix of weed (%)’ in Soilmentor – the Brix Barometer indicator works by examining the difference between these two brix readings.

3. Squish the handful of material into the garlic crusher.

4. Hold refractometer in one hand, flip back the plastic flap to expose the glass face.

5. Hold filled garlic crusher in the other and squeeze ‘juice’ from picked grasses onto the glass face of the refractometer.

6. You need just one drop of ‘juice’ on the glass screen. Then drop the refractometer’s plastic flap on top of the drop so it smears across the screen.

7. Hold the refractometer up to the sky (about 15degs) and look into the lens.

8. There will be an area/line on the scale where it changes from light blue below to dark blue above.

9. Record the number on the scale and make a note of whether the line is fuzzy or not in the notes section.

N.B. As a general rule of thumb, an optimum Brix value for grasses is 12 (and above).

10. Clean and dry the glass screen with your water ready for the next test

11. Remove residues from garlic crusher.

Watch the video below to see the brix method in action!


Use the code ‘SOIL#1’ on HarvestAgri to get a discount when buying:
Portable refractometer
Garlic press (sap squeezer)

Integrity Soils – How to Use a Refractometer