Most small farms in India apply fertiliser by habit. The same urea and DAP that the previous generation used, in roughly the same quantity, every season. Sometimes it works. Often a large share of that money is buying a nutrient the soil already has plenty of, while the nutrient that is actually limiting the yield goes unaddressed.
Soil testing costs very little and is available free or at nominal charge through the Soil Health Card scheme. The return on it is among the best available to a small farmer, and it takes one afternoon of work.
When to Sample
Sample after harvest and before the next sowing, when the field is empty. Do not sample immediately after applying fertiliser, manure or lime — wait at least two to three months, or the result will reflect what you just added rather than what the soil holds.
Testing once every two to three years is enough for most fields unless you have changed crops significantly or noticed a problem.
How to Collect the Sample Correctly
This is where most tests go wrong. A bad sample produces a useless report, and the farmer then concludes soil testing does not work.
- Walk the field in a zigzag pattern and mark 10 to 15 spots spread across it. Do not take everything from one corner.
- At each spot, scrape away surface trash — leaves, stubble, loose dust.
- Dig a V-shaped pit about 15 cm deep. Take a uniform slice from one wall of the pit, top to bottom. A slice, not a scoop from the bottom.
- Collect all slices in one clean bucket and mix thoroughly.
- Spread the mixed soil, divide into four parts, discard two opposite quarters, mix the rest, and repeat until about 500 grams remain.
- Air dry in shade, never in direct sun or over heat.
- Label clearly with your name, village, survey number, and the crop you plan to sow.
Sample Separately If
- Part of the field is noticeably different in colour, slope or drainage
- One section consistently yields less than the rest
- You are managing two blocks with very different cropping history
Avoid sampling from field bunds, near old manure heaps, along irrigation channels, under trees, or where animals shelter. These spots are not representative and will skew the whole report.
Where to Get It Tested
Soil testing laboratories operate under the state agriculture department in most districts, and Krishi Vigyan Kendras usually either test samples or direct you to the nearest lab. Under the Soil Health Card scheme, farmers receive a card carrying the results along with crop-wise fertiliser recommendations.
Reading the Report
pH
The most important single number. Most crops perform best between roughly 6.0 and 7.5. Outside that range, nutrients become chemically unavailable regardless of how much fertiliser you apply — which is why correcting pH sometimes raises yield without adding any nutrient at all. Acidic soils are treated with lime, alkaline soils with gypsum, and both take a season or more to respond.
Organic Carbon
An indicator of soil health and biological activity. Indian soils are widely low in organic carbon. This is not fixed by fertiliser; it is fixed by adding organic matter — farmyard manure, compost, green manure crops, and leaving residue on the field rather than burning it.
Nitrogen, Phosphorus, Potassium
Reported as low, medium or high, with values. These drive the fertiliser recommendation. A common finding on farms with long fertiliser history is high phosphorus and low nitrogen — meaning years of DAP has built up phosphorus that the crop cannot use faster, while nitrogen remains the actual constraint.
Micronutrients
Zinc, iron, boron, manganese, sulphur. Deficiencies here are widespread and cheap to correct, but they are invisible without a test. Zinc deficiency in particular is common in rice-growing areas and causes yield loss that farmers usually attribute to something else.
Acting on the Report
Take the recommendations to your KVK or extension officer and discuss them against your actual crop plan, because a report recommends for a crop, not for your rotation. Make one significant change at a time so you can tell what worked.
The most common outcome of a first soil test on a small farm is that the farmer reduces one fertiliser, adds one micronutrient, and spends less overall while yielding more. That result is not guaranteed, but it is common enough to make the test worth doing.
Soil recommendations depend on local conditions. Discuss your report with your Krishi Vigyan Kendra or state agriculture department before making major changes to your fertiliser programme.