How do I choose between mineral amendments?
Written by
Paul Reynolds
Reviewed by
Prof. Charles Hartman, Ph.D.To select the appropriate mineral amendments, you first need to know and understand your soil type. Your soil test will show the deficiencies that need to be corrected. I personally test my garden soil every two years like clockwork. Your amendment decisions should be based on actual mineral deficiencies rather than guessing.
Different minerals resolve soil problems. For example, gypsum helps alleviate sodium accumulation in saline soils. Greensand also adds potassium to help with clay compaction. Azomite - a natural mineral product - replenishes trace minerals lost in exhausted soil. I only use amendments based on the soil tests above. Your plants are happiest when applying minerals that correctly balance the soil.
Gypsum Applications
- Corrects sodium-dominant saline soils
- Improves water penetration in sodic conditions
- Apply only when soil tests show excess sodium
Greensand Uses
- Adds potassium to heavy clay soils
- Loosens compacted earth gradually
- Works best when organic matter is present
Azomite Benefits
- Replenishes zinc, boron and other trace minerals
- Supports plant disease resistance naturally
- Use only for confirmed micronutrient deficiencies
Take great care when applying minerals to control mineral rate imbalances. Creating imbalances through over-application can cause more damage than not applying something at all. Excessive gypsum can lead to drastically altered calcium-magnesium ratios, and excessive greensand can throw potassium levels out of whack. So, I carefully measure each application of mineral. Your soil needs a balanced mix of minerals for healthy plants.
The best results come when you combine minerals with organic matter. Greensand works really well with compost in clay soil. Gypsum works well with cover crops, especially in sodic soils. Azomite works well with aged manure. I also tend to layer minerals with organic amendments. Soil structure improves at a quicker rate this way.
Soil should be retested or retaken every 2-3 years to track progress. Remember that mineral amendments can be slow-acting, but the effect is profound. Greensand may take one to two years to see the benefits. Gypsum response occurs in 4-6 months. I keep careful garden journals. The amount of minerals you'd want to add will evolve as you retest your soil consistently.
Prioritize your most serious mineral deficiency first. Address sodium issues before addressing trace minerals, and correct potassium shortages before you add extras. I prioritize problems based on what the plant shows. Your targeted approach helps avoid stacked or compounding imbalances.
Read the full article: 10 Essential Organic Soil Amendments
