Soil Health · April 2025 · 4 min read
Earthworms are among the most visible and reliable indicators of soil health. Their tunneling improves drainage, their castings enrich fertility, and their abundance reflects the overall biological vitality of your soil.
Dig a one-foot-square hole about six inches deep and carefully sort through the soil, counting every worm you find. Repeat this in several representative spots across the field to get a reliable average. Counts are most accurate in spring or fall when soil moisture is adequate and temperatures are moderate.
Healthy agricultural soils typically support ten or more earthworms per cubic foot, while degraded soils may have fewer than five. High worm populations correlate with good organic matter levels, active nutrient cycling, and well-aggregated soil structure. A decline in earthworm numbers over time can signal problems like excessive tillage, chemical overuse, or compaction.
Reduce tillage intensity and frequency to protect burrows and avoid direct mortality from equipment. Maintain surface residue with cover crops or mulch to provide food and shelter for worms year-round. Avoiding harsh pesticides and maintaining balanced soil pH between 6.0 and 7.0 creates the conditions earthworms prefer.
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