Gardening in High-Phosphorus Soil: San Angelo, TX (Zone 7b)

A gardener in San Angelo, TX (Zone 7b, drought-prone) had soil test showing extremely high phosphorus. Wanted to know what perennials/vegetables tolerate it.

The Good News

High phosphorus is rarely toxic to plants. It can tie up iron, zinc, and manganese (causing deficiencies), but most plants grow fine. Your local farmers grow cotton and corn successfully in similar soils.

Management Strategy

1. Stop adding phosphorus. No bone meal, rock phosphate, or high-P fertilizers.
2. Add nitrogen. This balances the N:P ratio. Sources:
   • Composted manure (cow, horse, sheep, goat)
   • Chicken manure (high N, use sparingly)
   • Blood meal, feather meal, fish emulsion
   • Grass clippings (thin layers)
   • Legume cover crops (clover, vetch) – fix atmospheric N
3. Acidify if alkaline. West Texas soils are often alkaline (pH 7.5–8.5). High pH + high P = worse micronutrient lockup. Add elemental sulfur or acidifying fertilizers (ammonium sulfate).
4. Chelated micronutrients. Foliar spray or soil drench with chelated iron, zinc, manganese if deficiencies appear (yellowing between veins on new growth).
5. Organic matter. Compost improves everything: buffers pH, feeds microbes, enhances nutrient availability.

What to Grow

Almost anything. Vegetables: tomatoes, peppers, okra, melons, squash, beans, greens. Perennials: salvias, lantana, black-eyed Susan, coneflower, yarrow, ornamental grasses, sages, agastache. Native plants are pre-adapted.

Practical Steps

• For small beds: hand-mix 2–3" composted manure + 1 lb sulfur/100 sq ft.
• For large areas: hire a manure spreader; apply sulfur per soil test.
• Drip irrigation + mulch essential in drought.

You're not limited. Balance N:P, manage pH, add organics, and garden happily.