How Are Samples Chosen?
Have you ever been involved in a survey? Those phone calls in the middle of your evening at home asking you to answer a few questions or messages coming through your e-mail can be rather annoying. You have probably never wondered why you got picked. Most likely, you were selected because you meet some criteria that fits the demographic of the survey. Believe this, though: You were not picked totally at random. One of the primary keys to conducting an accurate survey is identifying and selecting potential respondents. This is done so that sampling sizes can be made manageable but—most importantly—provide accurate data. This is often observed during the Presidential election cycle, when surveys are conducted weekly in an effort to get an accurate idea of what people across the country are thinking. To create an accurate and manageable survey, participants are divided into demographic groups that have certain aspects in common.
When mapping soils, this technique of distinguishing likeness can be used to separate similar soils from other soils. Criteria that can be used to separate soils into groups include soil type, yield history, topography, cation exchange capacity, farming history, and others factors that are relevant to the tests being performed. This is the most accurate way to develop zones, which will be sampled separately from one another. Most zones will be from 8 to 12 acres in size.
How Many Samples Should Be Taken?
When sampling soil, a fairly large number of individual cores should be taken from each sample area. Usually, 12 to 20 cores will give an accurate representation of each identified area. Each sample can then be analyzed to determine the concentration of elements in each area. This allows for a quick, accurate, and rather inexpensive way to determine concentrations of elements.
This method of determining the areas in which to acquire samples will help you understand all the important characteristics of your soil. Most importantly, it will shed light on why various soils perform the way they do. There are other methods of sampling that require more samples to be taken; however, they involve taking fewer cores per sample area. These methods do not consider the differing characteristics of the soil. More samples do not inherently guarantee accuracy. Just as a survey randomly choosing individuals will not accurately depict attitudes about a certain topic, neither will randomly selecting soil samples give an accurate picture.
When developing sampling areas using a method that groups like soils, patterns can be seen and plans developed to supplement each distinct area. This method will help you understand your soil and discover what areas of the soil can be supplemented to most quickly grow your yield.
SoilRight helps farmers to control costs and improve soil health while protecting the environment for future generations. Click below for a free consultation, and find out how we can put your farm on the path to better soil health.