Refractometers are used for quite a lot of things — drug diagnosis, gemology, veterinary medicine, aquarium upkeep and farming.
In gardens and farming it is an all-in-one tool that can be used to test the health of your crops, via a brix rating system. A refractometer uses refractive light passing through plant sap or fruit or vegetable juice to take a reading of nutrient levels. A high rating is good news for your crops — they should be healthy, disease and pest resistant, high in nutritional value and you’re likely to have a good harvest. A low rating means that your crop will not grow to its potential due to some external limiting factor, such as: a dilution of its nutrients due to high nitrate content, a mineral imbalance in the soil allowing weeds to flourish and take from your harvest, a low calcium content in the soil or a low/steady boron reading indicating an issue with the translocation of sugars within the plant.
The refractometer is a cheap and effective way to take the guesswork out of growing, by giving you a scientific guide as to the health of your crops and an indicator on what to do to make them grow to their potential. It has no moving parts and is simple and easy to read — it is a gauge using a numbered scale. It is one of the most valuable measuring tools we can use in our systems.