The way the soil samples are taken is extremely important, as the recommendations you receive from soil tests will only be as good as the samples you send for analysis. Following the instructions below will assure that the samples you send are taken in the way we need them for a proper analysis.

When to take a soil sample

Soil samples may be collected at any time of the year, provided that the area is not suffering from prolonged drought, that no nitrogen has been applied in the last 30 days, and no sulfur has been used in the last six months.

Late spring and early summer sampling avoids the rush, shows the soil’s fertility at its best, and gives time to plan a soil fertility program that can begin directly following harvest if necessary. However, if no samples have been taken within the last two years, the best time to sample is as soon as circumstances permit.

Generally, sampling should be done every year if fertility is high and/or trace elements are being used to achieve top yields. CAUTION: without special arrangements, we recommend that if possible, no soil samples ever be sent for analysis when a soil is so extremely dry that plants will not grow there.

Prepare a map of the areas being tested

A good map makes your sampling repeatable from year to year and is useful at the time of fertilization. Designate a number, or some other identification, even a name – up to 8 characters – for each field. Use permanent lines such as roads, ditches, and fences for boundary lines.

Divide the field map into areas that have the same soil color, slope, texture, drainage, and past history of erosion. Each area should have the same cropping history, fertilizer and manure treatments, and the same intended crop for all the ground within that area. Assign each of the areas sampled a specific number or letter (or a combination of both) so you can correctly identify it.

For example, Field #2 could have three areas: A – the high ground, B – the sloping ground, and C – the low, level ground. The numbers written on the sample bag would be 2A, 2B, and 2C. See Figure 1 for the sample map.

It is recommended that sampled areas represent no more than 20 acres (8-9 hectares) the first year our testing program is used, even if soils are uniform in texture and relief. Areas with taller or shorter plants, different weed or grass patterns, higher or lower yields, etc., should be avoided or sampled separately if large enough to fertilize properly. The next time samples are taken, combine those areas that by analysis have been shown to be alike. You may wish to combine very small areas that have all the same characteristics, into one composite sample.

Sample at least 300 feet (92m) away from gravel or crushed limestone roads and stay at least 20 feet (6m) away from fence rows or the edge of a field.

Avoid, or sample separately the following:

• Eroded hillsides or low spots
• Terraces, ditch banks, roadbeds, or fence rows
• Animal droppings, urine spots, burn piles, manure, straw, or haystacks
• Areas around sheds, barns, and/or where buildings have formerly stood
• Lime, fertilizer, chemical spill areas, and fertilizer bands
• Dead and back furrows
• Drought-stressed areas
• Areas where large amounts of sulfur have been applied in the last two to six months or where nitrogen has been knifed in or recently broadcast in large amounts.

See also For Those Who Utilize Soil Tests.