What natural methods adjust soil pH?
Written by
Kiana Okafor
Reviewed by
Prof. Martin Thorne, Ph.D.Appropriate soil pH testing allows you to know when natural amendments surpass chemical treatments. The addition of wood ash to my clay-heavy plots increased soil pH faster than lime, while the addition of pine needles gradually decreased soil pH. A client had a significant improvement in the pH of the garden while growing roses after substituting aluminum sulfate with oak leaf mulch. The pH value improved from 7.6 to 6.9 within 8 weeks.
Acidifying Amendments
- Pine needles: 2-inch layer lowers pH 0.3 units annually
- Coffee grounds: Mix 1 cup per sq ft monthly for mild acidity
- Elemental sulfur: 1 lb/100 sq ft reduces pH 0.5 units in 30 days
Alkalizing Solutions
- Wood ash: 10 lbs/100 sq ft raises pH 0.5 units in 4 weeks
- Crushed eggshells: 5 lbs/100 sq ft provides slow calcium release
- Dolomite lime: 7 lbs/100 sq ft stabilizes pH for 2+ years
Soils are a reflection of their region, and using regional smarts to address soil differences is critical. For example, areas enjoying limestone bedrock will need to be treated with three times the sulfur that I apply to granite-based soil areas and coastal gardens do quite well with applications of seaweed because of the salt, as there will be fewer pH swings. Always take pH samples of the soil beneath the top layer to monitor pH levels. From my experience sampling at 6 inches has minimized swinging pH levels at the surface.
Use natural options with safety in mind. Wood ash dust requires you to wear an N95 mask. I learned this as a client became asthmatic after breathing wood ash dust. When applying elemental sulfur, wear gloves, and we also, rinse tools after using dolomite lime. The best outcomes with natural solutions occur when we recognize their strengths.
Read the full article: Soil pH Testing: 7 Essential Steps for Accurate Results
