How to take a soil sample correctly (and read the report)
A bad sample produces a confident, useless report. Here is the sampling method, and a plain-language guide to reading pH, EC, organic carbon, NPK and micronutrients.
Taking the sample
One composite sample should represent one uniform area. If soil colour, slope, irrigation or crop history changes, sample that part separately.
- Walk the plot in a zig-zag and collect from 10 to 15 spots
- Scrape off surface trash, then cut a V-shaped slice to 15 cm depth for field crops
- For orchards, sample at two depths near the active root zone, not against the trunk
- Mix all spots on a clean sheet, quarter the heap twice and keep about half a kilogram
- Air dry in shade, bag it, and label with name, village, survey number and next crop
- Avoid bunds, corners, fertiliser bands, cattle resting spots and freshly irrigated soil
Reading the report
Five numbers carry most of the decision.
- pH: below about 6 is acidic, above about 8.5 usually indicates sodicity; both restrict nutrient availability
- EC: a measure of salinity; high values need leaching and careful fertigation
- Organic carbon: most Indian soils test low, and this is the number that improves slowest
- Available N, P, K: reported as low, medium or high against the crop requirement
- Micronutrients: zinc, boron, iron and sulphur deficiencies quietly cap yield even when NPK is adequate
Turning it into a schedule
Start with your State agriculture university's recommendation for that crop and district, adjust for the soil test rating, deduct nutrients supplied by manures, and split the dose across the crop's uptake stages. A single basal application of everything is the most common way to waste fertiliser in India.
Common questions
- How deep should the sample be?
- About 15 cm for field crops, deeper and near the active root zone for orchards and plantations.
- Where can I get soil tested?
- State agriculture department soil testing laboratories, Krishi Vigyan Kendras and private laboratories, including ours. Government laboratories offer subsidised testing under the Soil Health Card scheme.
Sources
This guide is general information for Indian conditions and is not a substitute for the product label, official scheme rules or advice from your district agriculture or horticulture office.