How to Reduce Water Alkalinity for Gardening

Soil test

• 1

  Test the pH of the garden soil. The alkalinity of the water will impact the pH of the garden soil, which is ultimately what affects plant growth. If the pH is above 7, it will be necessary to reduce the alkalinity of the water.

• 2

  Cover the soil in the garden with a 1- to 2-inch layer of sphagnum peat moss. Work the moss into the top 8 to 12 inches of soil in the garden. Sphagnum peat moss typically has a pH of 3 to 4.5 and will counter the effects of the alkaline water source.

• 3

  Retest the soil pH. If the pH of the soil still has not been lowered to the desired levels, add more sphagnum moss to the soil. Adjusting soil pH to the optimal levels can take significant time and may require repeat treatments.

• 4

  Determine the pH of the soil and the alkalinity of the water source with the test kits. Use these results to calculate the amount and type of acid necessary to adjust the irrigation water, using the Alk Calc tool linked in the Resources. Using these results as a guide, add the appropriate acid in the recommended amounts to the irrigation water prior to watering the garden.