Session 7 - Soil Sampling

Question 1

Compost Sample

Answer 1

• 1 teaspoon / ca. 4 grams from at least 5 different areas of a small pile

or

• 20 different areas from a large windrow from various locations and depths
• combine them into a single bag
• do not fill more than 1/2
• seal bag with air inside
• label outside with permanent marker

Question 2

General Bag Care

Answer 2

• do not fill bag more than halfway (to reduce material you can mix samples outside of the bag in a bigger container)
• do not press out air, make sure its sealed with fresh air and oxgygen sealed inside it

Question 3

Labeling Bags

Answer 3

• label with water proof makrer on the outside of the bag
• sample name (claer reference in legend)
• date
• optional: who took it

Question 4

Sampling a Field with different areas (healthy crops, sick plants, weedy patches, etc.)

Answer 4

1. draw a map of the field and identify and number each area (H1, H2, H3, W1, W2, etc.)
2. take at least 3 core samples from one single weedy patch, mix in a bag (W1), mark reference on your drawn map, make notes if necessary (e.g. depression, lime was stored here, etc.)
3. move to the next weedy patch and take 3 core samples and mix and label (W2)
4. once a representative number of weedy patches have been sampled (40%) move on to the next category (healthy crops for example)
5. take at least 3 core samples from one single weedy patch, mix in a bag (H1), mark reference on your drawn map
6. continue until you have sufficient samples
7. analyzing these samples should give you a good information what is different within the SFW of the weedy/sick patches compared to the healthy crops and give you a clue about the general health of the whole field

Question 5

Sampling bare soil (e.g. field that was recently tilled)

Answer 5

1. take 3-4 samples from 5-6 areas per acre
2. select them randomly while ensuring they are well distibuted throughout the whole field
3. avoid areas not representative for the field (e.g. ridge line, depression, and so on), but mark sample areas them on the map for possible further questions
4. place all these sample in the same bag labeled “bare soil” and mix well before analyzing

Question 6

Sampling area with varying conditions (riges, depression, etc.)

Answer 6

1. study the landscape carefully and map out prominent features
2. take 5-6 samples from one area and mix them in a bag
3. do this for every area and label and mark them according to a numbering system on your map

Question 7

Liquid Sample Collection

Answer 7

1. pour liquid onto a clean, not-breakable container with a sealable opening, make sure it was thoroughly cleaned
2. only fill the container 1/3 to maximize space for air exchange
3. cover the screw cap with duct tape and place it into another sealed bag
4. clearly label the container with a waterproof marker from the outside

Question 9

How many individual pathogen organisms are required to cause disease?

Answer 9

dangerous to consume food with a number of pathogens of 800 CFU/ml

=

8 individuals on a whole slide of a 1:5 dilution of one drop (1/20 ml)

Question 10

What measures to take if you see pathogens?

Answer 10

wash and desinfect your hands, slides and everything that the sample material came in touch with

dispose or deactivate the waste responsibly

Question 11

How to dispose small amounts of contaminated soil, manure, compost or liquids

Answer 11

if the sample does not contain foreign pathogens and your municipality allows for it you could flush it down the toilet or place it in the garbage, local waste managemanet facilities are usually equipped to deal with small amounts of contaminated materials

if this isn’t possible you need to autoclave or pressure cook the materiale to sterilize it: 20 minutes at 121°C at 15 PSI

Question 12

How to deal with large amounts of contaminated material?

Answer 12

• make sure the material gets fully aerobic, at oxygen concentrations of >6ppm aerobic beneficials will have advantage over pathogens and outcompete them
• fully drying the material stops all microbial growth and all organisms go into dormancy, this dried material can then be composted correctly again

Question 13

How to recognize heavy metal contamination?

Answer 13

• no presence of any microorganisms (or only a few bacteria)

Question 14

How to deal with heavy metal contaminated samples?

Answer 14

• contact the sender and return the sample
• get in contact with local land fill/waste authorities and make sure to comply with local laws

Question 15

Do soil lab technicians do soil sampling?

Answer 15

No, this is the job of a consultant. But to instruct clients it might be necessary to explain them in detail how to take the samples.

Question 16

How to handle foreign samples?

Answer 16

Always sterilize even when you don’t see pathogens, to not release alien microbes into our local eco systems that might lack natural predators/competitors.

Question 17

Can a lab technician give advice on remedying the situation?

Answer 17

No, the only job is to quantify the organims in a sample. Advising is only permitted to certified consultants.