How is soil acidity measured?
Soil tests show soil acidity as a pH measurement, which is a measure of the strength or degree of the acidity or alkalinity level in the soil. A pH value of 7.0 is neutral. Values above 7.0 are alkaline and below 7.0 are in the acid range. Vegetable growers should remember that the ph scale is a logarithmic scale. A soil with a pH value of 6.0 is 10 times more acid than a soil with a pH of 7.0 and a soil with a pH value of 5.0 is 100 times more acid than a soil with a value of 7.0. Soil pH is not a measure of total acidity, and many soil tests will report a lime test index or buffer pH. This is a measure of active and reserve acidity, and lime recommendations are based on this number. Do vegetable crops vary in their response to soil pH? Yes. Crops not tolerant of acid soils and requiring a pH range of 6.0 to 6.8 on mineral soils are: asparagus, beet, broccoli, cabbage, cauliflower, leek, lettuce, melons, onions, and spinach. Moderately tolerant crops for a pH range of 5.5 to 6.8 inclu
