Soil Problem No. 3: Soil is alkaline.
Common to: clay soils, arid and semi-arid climates
Amendments to add: elemental sulfur, iron sulfate
When soil test results show high soil pH levels, your crops will benefit from some balance. Apply elemental sulfur and iron sulfate at rates dependent on your soil type—your soil-testing agency should provide recommendations. Elemental sulfur reacts slowly with the soil, so apply it the year before planting. The University of Minnesota recommends that additional iron sulfate applications of more than 7 pounds per 100 square foot be spaced one to two months apart. Amounts less than 7 pounds can be applied in a single application. It is safe to apply iron sulfate to plants.
Alkaline soils require continual buffering, so monitor your soil pH every one to two years and amend as needed. For perpetually alkaline soils, grow crops that tolerate high pH, including asparagus, beets,cabbage, lettuce, parsley and spinach.