KBS004: Baseline Soil Sampling - KBS GK12...

Soil Sampling Protocol

Background information

In this protocol, you will sample soils for lab analyses in the BioEnergy SusTainability experimental plots. In each plot (there are eight per block), you will sample two soil cores.

Timeline/Frequency

This protocol for soil characterization should be completed at least once a year in the fall in every plot. An optional spring sampling may also be completed. This protocol includes the following yearly tests:

Soil sampling Soil Density Soil Moisture Soil Nitrogen and pH

Materials

Site maps labeled with block and plot numbers Soil Sampling Data Sheet Clipboards Pencils Meter stick or metric tape measure Soil corer Butter knife

Instructions

As you read through and follow these instructions, remember that a plot is a 3 by 3 meter square, and that there are 8 plots in one block. Each plot in the whole BeSt experiment has a unique code. Look at the maps of your school’s blocks to find the unique codes of the plots you’ll be sampling, so that you will know how to label your soil samples.

Preparation

1. Using address labels or labeling tape, label one plastic bag for each soil sample you will collect. On each plastic’s bags label, write: your school district name, the date of sampling, the block number, and the plot number.

2. For each plot, label six bags identically. (e.g., “Vicksburg. April 10, 2011. Block 23. Plot 4.”). On three of the bags add a label that says “Dried Sample.” Label the other three bags for each plot “Wet Sample.”

3. Repeat step two for all of the plots that you will be sampling.

BEST Experiment Updated February 22, 2011Yearly Soil Protocols pg.1

Plot

Block

Plot

Block

4. Cover labels with clear mailing tape to secure label to bag and to protect against moisture5. Prepare sampling buckets. Each bucket should have the following: site map, clipboard with

data sheets, pencil, sharpie marker, butter knife, sampling bags, and soil corer.

Sampling Soil at the BEST Experimental Plots

6. Before you start, read through steps 7-11. 7. Each person who will be sampling should take at least two “practice” soil cores outside of the

experimental plots using the soil corer. Discard this soil (put it back approximately where you sampled it).

8. Randomly select a location within the experimental plot using the Randomization Protocol (found with the Biodiversity Protocols).

9. Have one person carefully walk into the plot to the area determined by the Randomization Protocol, trying not to disturb or step on growing plants.

10. When at the correct location, use the soil corer to obtain a soil sample to as deep as 15 cm into the soil.

11. On the Soil Sampling Data Sheet, record 1) how deep the soil corer went into the soil and 2) the width of the soil corer (diameter). Later on, (in the Density & Soil Moisture protocol), we’ll use this information to calculate the volume of the soil sample we took.

12. Use a butter knife to help remove soil from the corer. Put the soil sample into the appropriately labeled bag for “Dried Sample.” Use your site map to double check that the block and plot label on your bag matches the block and plot that you are sampling.

13. Take a second core and put this sample in the appropriate “Wet Sample” bag.14. Do steps 3-9 three times in each plot that you are sampling. You should end up with six

samples for each plot, three of which are labeled “Wet Sample” and three of which are labeled “Dry Sample.”

15. Take the soil samples back to the classroom/lab16. Store soil samples in their plastic bags in a refrigerator.


Soil Sampling Data Sheet School District: ______________________ Instructor/Fellow: ____________________

Date: _______________ Time: ________Weather: ____________________________

Soil Sampling

Block Number

Plot Number

Core Depth (cm)

Core Width (cm)

Notes


Soil Density and Moisture Protocol

Background information

The density and moisture of the soil in a given area can have a significant effect on the plants that grow there. Soil density gives a measure of how tightly soil particles are packed, which can be used as an indicator of the ease with which roots can grow through soil horizons. Soil moisture measurements indicate the ability of soil to hold or transmit water, which can affect groundwater recharge, surface runoff, and transpiration and evaporation of water into the atmosphere. It also describes the ability of the soil to provide nutrients and water to plants, affecting their growth and survival.

In this protocol, soil samples will be analyzed in the lab by taking both fresh and dry mass measurements, as well as volume measurements. To obtain accurate results from this protocol, it is essential that the soil sample used is very fresh and of a known volume.

Timeline/Frequency

This protocol should be completed annually in the fall, no more than 48 hours after the completion of the soil sampling protocol.

Materials

Fresh soil samples of a known volume Balances Soil sieve 100 ml graduated cylinders Large tray to sieve soil into (at least 12x12in) Weigh boat (small plastic tray to place on scale) Oven or other means of drying soil samples Data sheet

Instructions

Day 1


1. Retrieve a soil sample collected from when the soil sampling protocol was performed. Record the origin of the sample (treatment and block number shown on bag label) on the data sheet.

2. Retrieve the soil characterization and sampling data sheet. Refer to the depth (cm) and width (cm) measurements taken for your sample (found in the last table on the data sheet) to calculate the volume of the sample.

3. Sieve your fresh soil sample into the large tray. Collect the gravel from your sample that does not fit through the sieve and keep it for later use.

4. Record the mass of your empty, oven-safe weigh boat.5. Add the sieved soil to the weigh boat and then mass the sieved soil sample and weigh boat

together. 6. Subtract the mass of the weigh boat from the mass of the fresh soil sample and weigh boat to get

the mass of the fresh soil sample. Record this value on your data sheet as the mass of the sieved fresh soil.

7. Label your sieved soil sample and place it in the oven at 60° C for 48 hours to dry. If ovens are not available, lay the sample out on a paper towel for at least 48 hours to dry.

8. Fill a 100 ml graduated cylinder with 50 ml of water.9. Carefully drop the pieces of gravel collected from your soil sample into the graduated cylinder.

Subtract 50 ml (the initial height of the water) from the final height of the water to get the volume of the gravel placed in the cylinder. Record your answer on the data sheet.

If the water level reaches approximately 90 ml and there is still gravel left to be placed in the cylinder, stop adding gravel to the cylinder. Subtract 50 ml (the initial height of the water) from the final height of the water to get the volume of the gravel placed in the cylinder. Record this value (it should be approximately 40 ml). Empty out the graduated cylinder and put the pieces of gravel that were dropped in the cylinder off to the side. Repeat steps 8 and 9 until all the gravel has been placed into the cylinder. Add the volume of gravel from each cylinder together to get the total volume of gravel from the soil sample and then record this value on the data sheet.

10. Subtract the total volume of gravel from the initial soil core sample volume to obtain the volume of soil sample without gravel. Record this value

Day 211. Remove your soil sample from the oven.12. Record the mass of the dry soil sample and weight boat.13. Subtract the mass of the weigh boat from the mass of the dry soil sample and weigh boat to get

the mass of the dry soil sample. Record this value.14. To obtain the soil bulk density value, perform the following equation: (mass of dry soil / volume of

soil sample).15. To obtain the % soil moisture value perform the following equation: ((mass of wet soil – mass of

dry soil) / (mass of dry soil)) * 10016. Return soil sample to labeled Ziploc bag and store for later use.


Soil Density and Moisture Data Sheet

School District: ______________ Instructor/Fellow: ____________ Date: __________

Data

Day 1

1. Origin of sample (treatment and block number): _____________________________

2. Total volume of fresh sample (from soil sampling data sheet: ______________ (cm3)

3. Mass of empty oven safe weigh boat: ______________ (g)

4. Mass of sieved soil and oven safe weigh boat: ______________ (g)

5. Mass of sieved soil (Answer 4 - Answer 3): ______________(g)

6. Volume of gravel from: 1st cylinder ___(cm3) 2nd ___(cm3) 3rd ____(cm3) 4th____(cm3)

7. Total volume of gravel from sample (Answers from 6 added together):________ (cm3)

8. Volume of fresh soil sample without gravel (Answer 2 - Answer 7): ___________(cm3)

Day 2

1. Mass of dry soil sample and weigh boat: _____________(g)

2. Mass of dry soil sample (Answer 1 - Answer 3): ________________(g)

3. Soil density: __________________(g/cm3)

4. Percent soil moisture: __________________%


Soil Nitrogen and pH Protocols

Yearly Sampling

We will be extracting nutrients and pH from soil by placing soil in water. The same soil and water solution will be used to measure pH and nutrients.

Nitrogen Background information

Nitrogen (N) is important for plant growth. N is used to build proteins and chloroplasts (the machinery for photosynthesis). Measuring N in the BEST plots will give an opportunity to study the N cycle in soil!

Notice the figures above: To the left is nitrate and to the right is ammonium. How are they similar? How are they different?

The common forms of inorganic nitrogen are ammonium (NH4+) and nitrate (NO3

-). Notice the charge sign on the two molecular formulas—ammonium is positively charged (a cation) and nitrate is negative charged (an anion).

Because of these charges, ammonium and nitrate interact with soil differently. Soil also has a slight negative charge so ammonium can stick to it* (opposites attract!) whereas nitrate is repelled by it.

The negative charge of nitrate causes it to move in water through the soil and contaminate ground and surface water. Have you heard about high nitrate in drinking water?

Plants also prefer to take up ammonium because it is easier for them to incorporate into cell materials but can use nitrate as well. Microorganisms release N from dead plants, animals and other microbes through decomposition. Plants can take up this nitrogen (either as ammonium or nitrate).

pH Background information

Soil pH is important for the growth of plants. Solutions with a pH from 1-6 are acidic and solutions with 8-14 are basic. A solution with a pH of 7 is neutral. This is a measure of the concentration of hydrogen ions. Soil acidity is important because it impacts how much nutrients are available to


plants. Soil pH is measured by extracting soil in water. The ratio of water to soil can influence soil pH. It is important to use the same amount of soil and water among the school districts.

How to Measure Soil N and pH

Soil nutrients and hydrogen ions are bound in the soil. We cannot measure them when they are bound to soil. Scientists extract nutrients by placing the soil in a very concentrated potassium chloride (KCL) solution. The ammonium and nitrate dissolve into the water. We will be using distilled water for our exercise.

There are many ways to measure the concentration of ammonium and nitrate. Most involve complicated instruments. We are going to keep it simple by using water quality test kits. Scientists use fresh soil to measure nutrients. They would run analyses within a few days of collecting soil. We will be using dried soil. Be sure your soil is very dry.

Materials

Freshwater Master Test Kit (Aquarium Pharmaceuticals, Inc.) Insta-test nitrite-nitrate test strips pH meter or pH paper 2 specimen cups Spoon to measure soil Balance (accurate to 0.1 g) 100 mL graduated cylinders funnels filter paper or coffee filters tape & markers distilled water gloves goggles Data Sheet

Instructions

Gloves and safety glasses should be worn while performing this lab. Gloves will protect the sample from being contaminated. The chemicals used for the analyses are strong bases so safety glasses and gloves should be worn.

Step 1: Label your cups with your sample identification!

Using tape and Sharpie marker, label the cups with sample identification.Cup A will be labeled as: Block ___ Plot______ soil + waterCup B will be labeled as: Block ___ Plot______ soil + water solution

Step 2: Extract N

1. Weigh 5 g of soil into a specimen cup.2. Using a graduated cylinder, measure 50 mL of water and add it to your sample cup.


3. Carefully screw the lid onto the cup and shake by hand for 10 minutes.

4. We will use gravity filtration rather than vacuum filtration. Filter the extract (Cup A) through filter paper (filter paper or coffee filters) and collect the water solution (the water that comes through the funnel) in the second specimen cup (Cup B). Make sure that the label on the catching cup matches the pouring cup! (This takes a long time!)

Ammonium

1. Fill a clean test tube with 5 mL of water solution from Cup B (the test tube line).

2. Add 8 drops from the Ammonia Test Solution Bottle #1, holding the dropper bottle upside down in a completely vertical position to assure uniform drops.

3. Add 8 drops from the Ammonia Test Solution Bottle #2, holding the dropper bottle upside down in a completely vertical position to assure uniform drops.

4. Cap the test tube and shake vigorously for 5 seconds.

5. Wait 5 minutes for the color to develop.6. Read the test results by comparing the

color of the water solution to the appropriate Ammonia Color Card. The tube should be viewed in a well – lit area against the white area of the card. The closest match indicates the (mg/L) of ammonia in the water sample. Rinse the test tube with clean water after each use.

7. Record the amount of ammonium in the Nutrient data sheet.

Nitrate


Be sure to have dry hands when getting a test strip! Wet hands will ruin the test strips in the vial.

1. Place nitrate test strip in the water solution to measure nitrate concentration.2. Let strip sit in water for two seconds3. DO NOT shake off extra water 4. Read after 1 minutes5. Read the test results by comparing the color of the test strip to the appropriate concentration on

the vial. The test strip should be viewed in a well-lit area. The closest match indicates the (mg/L) of nitrate in the water sample.

6. Record the amount of nitrate in each sample in the Nutrient data sheet.

pH

1. Measure the pH of the water solution using the pH paper or meter. Dip the pH paper or calibrated pH meter in the water solution.

2. 2. Read the test results by comparing the color of the test strip to the appropriate concentration on the vial. The closest match indicates the pH. Record the pH value on the Data Sheet.

Calculate the amount of N (NH4+ or NO 3

- ) per gram of wet soil

As soil scientists (or farmers or gardeners), it isn’t particularly useful for us to know the concentration of nitrates or ammonia in the water solution. We want to know how much N is in the soil. So we must relate our measurement back to our starting soil. Here, you will have to pay close attention to units to do the calculation correctly. You have measured concentration (mg of N/L) and you know the volume of water you used (50 mL = 0.05 L) and the mass of soil you used (5 g).

€

mg NL

x volume of water (L)mass of soil (g)

= mg Ng soil

Calculate the mg of N of nitrate and ammonium in a gram of soil. Put this number on the data sheet.


Nutrient Data Sheet

School District: _______________________ Instructor/Fellow_________________

Date________________ Time:_______________ Weather:______________

Grams of soil used__________(g)

Volume of water used___________ (mL)

Volume of water used in liters _______________ (L)

How would you describe the color of the result for ammonium?____________________

How would you describe the color of the result for nitrate?________________________

Concentration of nitrates ___________________ mg/L in water solution

Concentration of ammonium ___________________ mg/L in water solution

Amount of nitrate-nitrogen per gram of soil ____________________

Amount of ammonium-nitrogen per gram of soil ____________________

What is the nitrate concentration in distilled water? ___________

What is the nitrate concentration in distilled water? _____________

pH of distilled water _________

Block _____ Plot _____ pH Measurement method (check one): ❒ paper ❒ meter

pH of water solution _________


KBS004: Baseline Soil Sampling - KBS GK12...

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