TX Organic Research Center



There is a terrific instrument that every organic gardener and grower should have. I should also talk about more often. It is called Refractometer and is an optical instrument used to measure the amount of dissolved solids in a liquid. It shows the sugar levels in plant tissue. It has been used in the grape growing industry forever.
A refractometer gives growers the percentage Brix, which is the relative "sugar weight" of a sample compared to distilled water. It can be used on all plants and all fruit. Brix is sometimes referred to as Balling. The refractometer works much like a prism - it reacts differently to light (by giving a reading on a scale) depending upon

the amount of sugar that is available   in the liquid sample held between the daylight plate and the main prism assembly. As light moves through different medium, it’s speed changes. When light comes into the refractometer prism at an angle, it bends as it moves from one material to another. It bends toward the denser material. Due to optical density, light slows down when passing through a dense liquid. Simply place sample on glass and close the daylight plate (with not bubbles or air spaces showing. Light enters from all angles.  


Refractometers are traditionally used to test ripening fruits and vegetables; however they can be used for “Plant Sap Analysis”. Sap is squeezed from fresh plant tissue (leaves or petioles) and tested for Brix or sugar content. The higher the sugar, the healthier the plant and the better the taste. Food products are healthier for people and animals and all plants with higher Brix readings have few to zero insect and disease problems. The sap pH indicates the level of balance of nutrient uptake and helps to identify which elements may be out of balance.
Devices are available from places like Pike Agri-Labs Supplies, Inc. www.pikeagri.com

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