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Sample Collection for Variable Conditions in Same Field/Area

Examples that fit this category:

--A field with areas of both sick and healthy plants of the same type

--A field (pre-planting) with varying degrees of saturation, soil type, or land-use history


Materials required:

  • Paper to draw a map

  • An apple corer or pipe that is about 0.5 to 1.5" interior diameter

  • One resealable plastic bag per sample to be analyzed

  • Permanent marker to label bags

  • Sterilized plastic bucket

1. Draw a map of the area to be sampled: it should include both the areas where plants are struggling as well as the areas where they are healthy. Assign each sick area a number. Draw a grid over the healthy plant area and divide it into 9 squares.

2. Go to the first (if more than one) sick plant area and randomly choose 3 plants. At each plant, collect 3 soil cores. Each core needs to be taken from halfway between the step and drip line of the plant for most accurate soil biology representation. To take a soil core, move aside the top layer of dead or living plant material if present and then collect only the top 3 inches of the soil with your apple corer or pipe. place these 3 soil cores into a bag if sampling a small area or bucket for larger areas. Each sick area will be assessed independently, so use one bag per sick area. Label each bag with its corresponding area number.

3. On the map, go to the area with healthy plants and use a random number generator to come up with however many numbers to match the number of sick areas that you collected soil from. If you collected soil cores from 2 sick areas, then generate 2 random numbers (from 1 to 9). These two numbers will be where you collect soil cores from on the healthy plant grid. If you get 3 numbers that line up in a row on the grid, keep generating random numbers until they do not. Just like before, at each square randomly choose 3 plants. At each plant, collect 3 soil cores. Place these 3 soil cores into a bag and label it with the area number from which it came. Do this for each healthy area. Since each healthy area will be assessed independently, make sure to use one bag per grid area.


4. Fill a plastic bag 1/3 to 1/2 of the way full and then seal the bag. It is very important not expel the air from the bag as this will limit the oxygen available to the biology in the sample which may result in anaerobic conditions being formed.


5. All sample bags should be labeled with the area name, area, date, and time collected on the *outside* using a permanent marker or an affixed label. Please do not put any identifying information about your

sample on a piece of paper and place it inside the bag. The paper will disintegrate, become food

for microbes, and potentially change the biology of your sample. 

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