IN YOUR ORCHARD
TIME TO CONSIDER Now that the California almond harvest has wrapped up, growers are shifting their focus to post-harvest tasks. One question I often hear from people outside the industry is, “What are those white piles on the edge of the field?” Almond growers know these are typically soil amendments. The more common questions I get from growers themselves are: “Should I use gypsum or lime?” and “Is sulfur really necessary?“ In today’s article I’m going to break down the differences between some common soil amendments and how they might fit into your operation.
Gypsum Gypsum is a great option for when you need calcium but don’t want to alter your soil pH. It’s pH neutral, meaning it won’t raise or lower pH levels. Gypsum helps break up clay soils and improves water infiltration. If you’re dealing with sodium issues or poor drainage, gypsum can be especially beneficial. When combined with good winter rains, it can help flush sodium out of the root zone. It’s typically applied using a broadcast spreader, with application rates varying based on specific conditions. Best Use: Heavy clay soils, high sodium levels, or when calcium is needed without affecting pH. Ag Lime Ag lime is ideal for soils that are too acidic. It raises pH and supplies calcium. If you’re unsure about your soil’s pH, a simple soil test can provide clarity—your PCA or CCA can assist with this. If your soil test indicates a low (acidic) pH, lime can help restore balance. Keep in mind that lime works gradually, depending on soil type, so results won’t be immediate. Like gypsum, it is applied with a broadcast spreader, and rates depend on your soil’s pH level. Best Use: Acidic soils needing a pH increase and calcium. Dolomite Dolomite is similar to Ag Lime but includes magnesium. It raises pH and adds both calcium and magnesium. If your soil test shows low magnesium levels, dolomite is a solid choice. Magnesium is essential for photosynthesis, and maintaining a proper calcium-to-magnesium ratio is
key to overall plant health. Dolomite is also applied with a broadcast spreader, and results may take time depending on soil type. Application rates vary based on pH. Best Use: Acidic soils with low magnesium levels. Sulfur Sulfur has the opposite effect of lime—it lowers soil pH. If your soil is too alkaline, sulfur can help bring it down. In addition to adjusting pH, sulfur also contributes an essential nutrient. It’s important for protein formation and nitrogen uptake in plants. Like lime and dolomite, sulfur takes time to work. It’s typically applied in pelletized form using a broadcast spreader with rates dependent on your soil’s pH. Best Use: Alkaline soils. Quick Comparison
Nutrients Supplied
Amendment pH Effect
Best For
Poor infiltration, sodium issues
Calcium, Sulfur
Gypsum Neutral
Ag Lime Raises
Calcium Acidic soils
Acidic soils with low magnesium
Calcium, Magnesium
Dolomite Raises
Alkaline soils
Sulfur
Lowers
Sulfur
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ALMOND FACTS
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