Soil testing tells you what nutrients your soil already has, what it is missing, and whether problems like acidity or salinity are holding your crops back. It is one of the cheapest investments on a farm and the starting point for any sensible fertilizer plan. Without it, you are either wasting money on nutrients the soil does not need or losing yield to deficiencies you cannot see.
Why soil testing matters
- Saves fertilizer money by avoiding unnecessary applications
- Improves yields by correcting real deficiencies
- Identifies pH and salinity problems that limit nutrient uptake
- Tracks soil health over time, especially organic carbon
When to test soil
Test each field every two to three years, ideally before the main season and well before sowing so you have time to act on results. Sample after harvest and before applying fertilizer or manure – never right after fertilizing, which distorts results.
How to take a soil sample correctly
A lab can only analyse what you send it. A poor sample gives a misleading report.
- Divide the farm into uniform areas. Sample fields separately if they differ in soil colour, slope, cropping history or past fertilization.
- Collect from multiple spots. Walk the field in a zigzag and take soil from roughly 10–15 spots per uniform area.
- Sample at the right depth. For most field crops, take soil from the plough layer, around 0–15 cm (0–6 inches). Orchards and deep-rooted crops may need deeper samples – follow your lab's advice.
- Use a V-shaped cut. Clear surface litter, dig a V-shaped hole to sampling depth, then take a uniform slice from one side.
- Avoid unusual spots. Do not sample near bunds, trees, irrigation channels, compost heaps or where fertilizer was recently spread.
- Mix and reduce. Mix all cores thoroughly in a clean bucket and keep about half a kilogram.
- Label clearly. Field name, date, depth, previous crop and next planned crop.
Use clean plastic tools and bags – avoid fertilizer bags and rusty tools, which contaminate the sample.
How to read a soil test report
Soil pH
pH measures acidity or alkalinity. Most crops grow well in roughly the 6.0–7.5 range. Strongly acidic soils may need liming; alkaline or sodic soils may need gypsum and organic matter. pH affects how available other nutrients are, so correct it first.
Electrical conductivity (EC)
EC indicates salt content. High EC means salinity, which reduces water uptake and yields, especially for salt-sensitive crops.
Organic carbon
Organic carbon is a key indicator of soil health – it improves structure, water holding and nutrient supply. Low organic carbon is common in intensively cropped soils. Build it with crop residues, compost, manure and crop rotation with legumes and green manures.
Primary nutrients: N, P and K
Reports usually rate nitrogen, phosphorus and potassium as low, medium or high. Fertilizer recommendations are adjusted from the standard dose: increased when the level is low, reduced when it is high.
Secondary and micronutrients
Many reports also include sulphur, zinc, iron, manganese, copper and boron. Zinc deficiency, for example, is common in many intensively cropped soils and can be corrected cheaply once identified.
Turning results into action
- Correct pH problems first
- Adjust fertilizer doses for each field based on its own report
- Address deficiencies of micronutrients identified in the test
- Plan organic matter additions for low organic carbon soils
- Retest after two to three years to track improvement
In India, the government Soil Health Card scheme provides soil testing and field-specific fertilizer recommendations – contact your local agriculture office or Krishi Vigyan Kendra.
Keep soil data with each field
Soil reports are most useful when they sit alongside each field's cropping and fertilizer history. AgriFarm field management keeps soil details and records per field so you can see how soil health changes over the years.
Frequently asked questions
How often should I test my soil?
Every two to three years per field is a good routine, or more often if you are correcting a specific problem like low pH.
Can I test soil myself?
Home kits give rough pH and nutrient indications, but a laboratory test is far more accurate and comes with fertilizer recommendations.
