7 Signs Your Soil Is Getting Healthier — No Lab Test Needed

A soil test tells you what is in your soil. Field observation tells you what your soil is doing. Both matter. But between annual soil tests, your farm is giving you daily signals about whether the soil biology is recovering or declining. Learning to read these signals is the most valuable skill an organic farmer can develop.

Here are seven indicators that any farmer can observe and track, season by season, without any equipment.

How Do You Measure Earthworm Count as a Soil Indicator?

The earthworm is the most reliable single indicator of soil health. Earthworms only thrive in soil with sufficient organic matter, appropriate moisture, no toxic residues, and active microbial life. If earthworms are present in high numbers, almost everything else about your soil biology is also in good shape.

How to measure: Dig a 30 cm x 30 cm x 30 cm cube of soil. Do this in the morning when the soil is moist, not after a dry week. Count every earthworm — large, small, and juvenile. Record the number.

What the numbers mean:

• 0–5 per cube: Soil is biologically depleted
• 6–15 per cube: Recovering, biology is rebuilding
• 16–30 per cube: Healthy, productive soil
• 30+ per cube: Excellent — your soil is thriving

In Organic Mandya’s tracking data, farms starting ZBNF typically begin at 2–5 earthworms per cube. After two years of consistent jeevamrutha application and mulching, most farms reach 15–25 per cube. Do this test in the same spot at the same time each season. The trend matters as much as the absolute number.

How Do You Test Water Infiltration Rate in the Field?

Healthy soil absorbs water quickly. Compacted, biologically dead soil repels it — water runs off the surface, taking topsoil with it, instead of soaking in.

How to measure: Drive an open-ended tin can (both ends removed) 5 cm into the soil. Pour one litre of water into it. Time how many minutes it takes to completely absorb.

What the numbers mean:

• More than 20 minutes: Severely compacted, poor infiltration
• 10–20 minutes: Moderate compaction
• 5–10 minutes: Good infiltration
• Under 5 minutes: Excellent — highly porous, biologically active soil

Repeat this test in three different spots in the field and average them. Do it before the first Kharif rain each year. A 2-minute improvement per season is a clear sign the organic matter and earthworm channels are working.

What Does the Soil Smell After Rain Tell You About Soil Health?

Healthy soil smells. That distinctive, deeply pleasant earthy smell that rises from the soil after rain is produced by a specific compound called geosmin, which is released by actinobacteria — a group of soil bacteria that are among the first indicators of biological health.

Chemically farmed soils with low organic carbon produce almost no smell after rain. The absence of smell is the absence of biology.

How to track it: After the first significant rain of the season, walk your fields and notice the smell. Is it strong and pleasant? Faint? Absent? You cannot quantify this exactly, but farmers who do this consistently report that the smell becomes noticeably stronger each year as organic matter builds. By year three of organic farming, several farmers in our collective describe their fields as smelling “like a forest floor.”

What Does Soil Crumb Structure Tell You About Soil Health?

Pick up a handful of moist (not wet) topsoil and squeeze it, then open your hand and crumble it gently. Healthy soil breaks apart into small, irregular aggregates — crumbs — rather than into dust or a solid clod.

These aggregates are held together by fungal hyphae (threads), bacterial biofilms, and organic matter. They create the pore structure that holds both air and water simultaneously — the Whapasa condition that Palekar describes as the ideal root environment.

What to look for: Crumbs that hold their shape loosely, break apart easily with gentle pressure, and feel slightly spongy rather than hard. The presence of white threads in the soil (fungal mycelium) is an excellent sign. Soil that crumbles to powder (low organic matter) or forms solid clods (compacted, clay-dominated) is not yet healthy.

What Does a Weed Species Shift Indicate About Your Soil?

The weeds growing on your farm tell you something precise about your soil chemistry and biology. Different weed species are indicator plants for different soil conditions:

• Purslane (Portulaca), amaranth, black nightshade: These colonise disturbed, bare soils with low organic matter. Their presence in large numbers early in your organic transition is normal and expected.
• Parthenium (congress grass), lantana: Indicate low biological activity and disturbed soil chemistry. Common on chemically farmed land.
• Clover, wood sorrel, vetches: These indicate improving soil — they are nitrogen fixers and prefer biologically active environments. Their appearance in your field means soil health is improving.
• Diverse mixed weeds in low density: The ideal state. Healthy soil has weeds, but no single species dominates, and the diversity increases year over year.

Track the dominant weed species on your farm each season. A shift from monoculture weeds to diverse, mixed growth is a reliable sign of soil recovery.

How Does Root Depth and Structure Reflect Soil Health?

At harvest time, pull a plant from the ground and look at its roots. Healthy soil produces roots that go deep and branch extensively. Compacted, low-biology soil produces shallow, stunted root systems.

How to measure: When harvesting ragi, pull a complete plant and lay it on flat ground. Measure the depth of the deepest root. Also observe: are the roots smooth and sparse, or branching and fibrous? Healthy ragi roots in good soil reach 40–60 cm depth. In compacted soil, they rarely pass 20 cm.

The root architecture reflects the soil architecture. More pore space from earthworm channels and fungal networks means roots can explore more soil volume — which means more nutrient and water uptake, which means better yield.

What Does a Crop Vigour Comparison with Neighbours Reveal?

This is the simplest observation and requires no tools. Stand at the boundary of your organic field and your neighbour’s conventional field (or your own field from previous seasons if you have photos). Look at:

• Leaf colour: A deeper, more uniform green in organic crops indicates better nitrogen availability through microbial fixation.
• Stem thickness: Thicker stems indicate better silica uptake and overall mineral nutrition.
• Crop uniformity: Organic fields in the third year and beyond tend to show more uniform growth because the soil biology is more uniform across the field.
• Pest damage level: By year two, most farmers in our collective notice significantly less pest damage on organic crops compared to neighbours’ conventional crops on similar land.

How Should You Track These Soil Indicators Over Seasons?

The value of these observations is in the trend, not a single data point. Start a simple notebook — or even a voice note on your phone — after each season. Record earthworm count, infiltration rate, soil smell (1–5 scale), dominant weed species, and a root depth measurement. Over three to four seasons, you will have a field-level soil health record that no external test can give you. It is also the most compelling evidence you can show to sceptical family members, buyers, or certifiers.

Your soil is telling you how it is doing. The skill is in learning to listen.