Obtaining a Soil Sample
Soil samples for nutrient factors should be obtained from the top 6” profile of the soil, taken with a soil sampling tube, auger or spade. Because of many soil variations in one field or area to be tested, it is necessary to obtain 15 of these small portions or plugs of soil from a random grid, representing the many variants that may occur throughout the test area. Composite these samples into a bucket, mix well and air dry for several hours. Place approximately 1 cup of this soil in an A & L Midwest Lab bag, and fill out the necessary form. For a normal soil test report used in our Bio System program, check items 1A, 2, 3, and NO3N on the sample form. (See example, next page.) If an anaerobic and aerobic bacterial plate count is needed, simply write it across the face of the form.
Obtaining a Tissue Sample
For tissue tests, we prefer to use quite a different approach than others.
For annual crop plant up to 6” tall:
Send entire plants from 15 different field locations.
For annual crop plants over 6” tall:
Sample the bottom leaf closest to the ground, then leaves from half way up the plant, then a sample from a new growth tissue. As with the smaller plants, you will need these samples from 15 different plants from random field locations.
It is our belief that a petiole test on any plant tissue test is not a correct reflection of the nutrition present in the plant leaves. We do not believe that selecting leaves from only one location, (i.e. 3rd leaf from top), is an acceptable method either.
Plant diseases usually begin on the lower leaf tissue. In light of the fact that certain elements are mobile and always drawn to the new tissue or reproductive organs, it only makes sense to have a sample representing the whole plant rather than just the new or middle aged tissue. Quite frequently the new growth will not reflect true overall plant tissue deficiencies.
On perennial crops, trees and shrubs, a sample leaf from an older branch, and one leaf from the new tissue area should be combined from 15 representative plants.
On golf greens a mower-obtained sample will suffice; but on fairway grasses the sample should represent as much of the whole plant as possible.
Avoid tissue in all cases from excessively dusty leaves; or rinse leaf tissue sample in water prior to drying. If next day or second day shipment is made, drying the sample is not necessary. For conventional shipping, dry the tissue before placing in Midwest Labs tissue sample bag. Fill out tissue test form, indicating complete analysis.