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How To Take Soil Samples For Analysis?

Soil testing or soil analysis is an important factor in commercial farm management. However, the result of soil analysis hugely depends on the preparation of the soil samples. Moreover, you must take soil samples in the right way to get the perfect result.

Right Soil Sampling Time

Collect a soil sample a few months before initiating any new landscaping—whether it be laying sod, starting a vegetable garden, putting in a flower bed, or planting perennials. In this system, you will have enough time to apply the inputs to adjust the soil pH before you plant.

Sample established areas—lawns, trees, shrubbery, and other perennials—once every three or four years. You can sample at any time of year. However, select an ideal time to take samples according to your crop.

Read: Is Soil Testing Important In Agriculture?

If an established area exhibits abnormal growth or plant discoloration, take a soil sample right away. You can submit matching plant tissue samples or separate soil samples for nematode assay. However, avoid the areas recently limed or fertilized, at least for six to eight weeks.

Here are the 5 Steps to Take Soil Samples for Analysis

1. Divide The Field To Collect The Samples

For routine soil fertility testing, first, traverse the field to be sampled. Note variations in slope, color, texture, management, and cropping pattern. Demarcate the field into uniform patches. So that you can take samples separately from each.

2. Do not Sample Unusual Area

Avoid areas recently fertilized, old bunds, marshy spots near trees, compost heaps, and other non-representative locations.

3. Use Proper Sampling Tools

You can take samples satisfactorily with a soil tube auger spade, trowel, Khurpi, or pickaxe. In addition, you must clean the tools. Ensure, the tools are free from fertilizer contamination. Also, you can use other accessories like a bucket, information sheet, plastic or tarpaulin piece, and cloth bag labels.

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4. Soil Samples Collection Process

First of all, remove organic debris, rocks, and trash from the surface of the soil sampling areas. You will need to do it before collecting the soil samples. Select the sampling spot in a zigzag manner from about 10-20 places. Collect all the samples in a bucket. However, you must maintain the depth of sampling according to the purpose.

  • Soil fertility (15-25 cm)
  • Salinity and alkalinity (1m)
  • Establishment of gardens (2m)
  • Soil survey profile of (1-1.5m ) depth

Keep a record of the areas sampled and a simple sketch map for reference.

5. Handling and Dispatch of Samples to Laboratories

After the complete collection of soil samples from the field, you must do some grading and sorting. You will need to remove the organic residues like tree leaves, dung, etc, and gravels, stones, and other unwanted materials. In addition, you must adopt the following steps for preparing the soil sample for laboratory analysis.

  • Drying
  • Grinding
  • Sieving
  • Mixing
  • Partitioning
  • Weighing
  • Storing
  • Labeling

After collecting, you must keep the soil samples air-dried first. And then you will need to go for grinding. However, you can use a wooden mortar and pestle for grinding to avoid contamination in the soil sample.

After grinding, you must sieve the soil samples with a 20-80 mesh sieve. And then mix all soil samples thoroughly by spreading them over cloth or paper.

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From this bulk soil sample, you will need to collect one representative soil sample following the quartering method of portioning. About 250 to 500 g of the soil sample is sufficient for analysis. You must store the sample in dry and clean poly bags, screw cap jars, or cardboard boxes with proper labeling.