Soil Minerals and Soil Prescriptions for Organic Gardeners


Refractive Index of Fruits
Calibrated in % Sucrose or Brix 
Originally Compiled by Carey Reams

Fruit Poor Average Good Excellent
         
Apples 6 10 14 18
Avocados 4 6 8 10
Bananas 8 10 12 16
Cantaloupe 8 10 12 14
Cherries 6 8 14 16
Coconut 8 10 12 14
Grapes 8 12 16 20
Grapefruit 6 10 14 18
Honeydew 8 10 12 14
Kumquat 4 6 8 10
Lemons 4 6 8 12
Oranges 6 10 16 20
Papayas 6 10 18 22
Peaches 6 10 14 18
Pears 6 10 12 14
Pineapple 12 14 20 22
Raisins 60 70 75 80
Raspberry 6 8 12 14
Strawberry 6 10 14 16
Tomatoes 4 6 8 12
Watermelon 8 12 14 16

 

"For reference, pure water has a reading of "0".  Within a given species of plant, the crop with the higher refractive indes will have a higher sugar content, higher mineral content, higher protein content and a greater specific gravity or density.  This adds up to a sweeter tasting, more minerally nutritious food with a lower nitrate and water content and better storage characteristics.  It will produce more alcohol from fermented sugars and be more resistant to insects, thus resulting in a decreased insecticide usage.  Crops with a higher sugar content will have a lower freezing point and therefore be less prone to frost damage."

from Arden Andersen Science in Agriculture p 362 (AcresUSA pub 2000)

Refractive Index of Vegetables and Forage
Calibrated in % Sucrose or Brix 
Originally Compiled by Carey Reams

Vegetable or Forage Poor Average Good Excellent
         
Alfalfa (Lucerne) 4 8 16 22
Grains 6 10 14 18
Sorghum 6 10 22 30
         
Asparagus 2 4 6 8
Beets 6 8 10 12
Bell Pepper 4 6 8 12
Broccoli 6 8 10 12
Cabbage 6 8 10 12
Carrots 4 6 12 18
Cauliflower 4 6 8 10
Celery 4 6 10 12
Corn Stalks (green) 4 8 14 20
Corn (Maize), young 6 10 18 24
Cow Peas 4 6 10 12
Endive 4 6 8 10
English Pea 8 10 12 14
Escarole 4 6 8 10
Field Peas 4 6 10 12
Green Beans 4 6 8 10
Hot Peppers 4 6 8 10
Kohlrabi 6 8 10 12
Lettuce 4 6 8 10
Onions 4 6 8 10
Parsley 4 6 8 10
Peanuts 4 6 8 10
Potatoes, "Irish" 3 5 7 8
Potatoes, Sweet 6 8 10 14
Rutabagas 4 6 10 12
Squash 6 8 12 14
Sweet Corn 6 10 18 24
Turnips 4 6 8 10