Alkaline Soil Treatment

Organic Matter

• The cheapest method of lowering pH involves incorporating organic matter into your soil. Soils with higher organic content have a lower pH and higher quantities of the nutrients plants need. Most organic mulches and composts help, but acidic materials like sphagnum and peat moss are best. This is not a quick-fix solution, as it takes time for these materials to have an effect. Plan on planting your crops the season after you start working your soil.

Sulfur

• Sulfur is available in two forms available to gardeners: aluminum sulfate and elemental sulfur. Aluminum sulfate works fastest, producing acidity as soon as it dissolves into the soil. Elemental sulfur takes time, sometimes up to a full season, as bacteria gradually convert it to sulphuric acid. Neither form lowers pH permanently and may need reapplication every few years. Use aluminum sulfate in higher quantities. It takes 4.2 lbs. of aluminum sulfate per 10 square feet to lower the pH from 8.0 to 5.0, while 0.6 lbs. of elemental sulfur has the same effect.

Raised Beds

• Plant your crop in raised beds with soil amended with aluminum sulfate or elemental sulfur. Soil in raised beds maintains its pH longer than the surrounding soil. However, the soil in raised beds may lose nutrients faster due to leaching, so you might need to fertilize your plants more often.

Alkaline-Tolerant Plants

• Garden vegetables like asparagus, beets, cauliflower, cabbage and celery tolerate a pH as high as 8.0. A number of trees and shrubs also thrive under alkaline conditions, including silver maple, barberry, lilac, bur oak, cotoneaster and creeping juniper.