Determining Soil Physiological Characteristics

I.              Determining Soil Morphological Characteristics

a.    Objective:

·   Enumerate the process of the identification of basic soil physical properties (color, depth, soil layer boundary, pores, pebbles, gravels and stones) of soil samples.

b.    Materials:

·   Munsell color chart

·   Shovel

·   Bolo

·   Sticks/ Markers

·   Meter stick

c.    Procedure:

·   Identifying soil layer boundaries

1.    Create a pit for approximately 2 meters using shovel

2.    Choose a section or phase in the created pit that is exposed to sunlight

3.    Identify the change in color of the soil sample

4.    Establish points with the aid of sticks/markers to identify soil layer boundaries

5.    Enumerate the number of layers

·   Identifying soil depth

1.    Choose at least three (3) points in the established soil layer boundaries

2.    Measure the soil using the meter stick vertically from the surface of the soil down to the chosen established points

3.    Record and tabulate the acquired data. The depth of the soil is in negative value since the soil is measured vertically downward. (e.g    0 to -40cm)

4.    Sketch the chosen region with its established point to identify the soil’s transition.

·   Describing soil pores

1.    Observe visible pores present in every layer of the soil

2.    Measure the diameter of each pores present in every layer of the soil

3.    Categorize the measured pores by setting range of sizes from small, medium and large. (e.g. small 0.5- 2.0 , medium 2.1-4.0, large 4.4-5.1)

4.    Record and tabulate data.

·   Describing present gravels, stones, and pebbles

1.    Observe visible sedimentary fragments present in every layer of the soil

2.    Measure the diameter of each sedimentary fragments present in every layer of the soil

3.    Categorize the measured sedimentary fragments by the ranges of sizes from course sand (0.5 mm - 1.9mm), granule (2mm- 4mm), and pebble (4mm-64mm).

4.    Record and tabulate data.

 

·   Describing present plant roots

1.    Observe for visible plant roots present in every layer of the soil region.

2.    Measure the apparent roots through its diameter.

3.    Categorize the measured diameter by the range of the sizes of the present plant roots. (e.g. small 0.005-0.01, medium 0.02-0.09, and large (0.1-0.5)

4.    Record and tabulate the data gathered in each layer.

 

 

II.            Determining Soil Physical Characteristics

a.    Objective:

·   Enumerate the process of the identification of basic soil physical properties (color, structure, and texture) of soil samples.

b.    Materials:

·   Water

c.    Procedures:

·   Soil Color

1.    Observe the change in color in every layer.

2.    Using a bolo get a sample of the soil in each layer

3.    Identify the color of the soil with the aid of Munsell Color Chart.

4.    Record and tabulate the data.

 

·   Soil Texture

1.    Take a handful of soil about 25 grams.

2.    Remove the impurities (pebbles and visible bits of organic matter like roots etc.) in the soil sample.

3.    Break apart the aggregates to find the differing proportions of each of the components in the soil.

4.    Identify soil texture in every layer through field method (feel, roll,and ribbon).

5.    Perform Feel Method.

A.   Add a little bit of water to the soil sample until it is kind of moist putty.

B.   Adjust this by adding either dry soil or water.

C.   Form the soil in to a ball but some will not form into a ball. This means that the soil is sandy soil.

D.   Distinguish whether it is gritty, smooth or sticky.

a.    Take a small amount from the soil sample and put it on the palm of your hand

b.    Add quite a bit of water and then using your finger rub the soil against your palm.

c.    If there are bits of sand then it is gritty, if silt is dominant then it feels floury or smooth and if the soil sample is abundant in clay then it is dine or sticky.

6.    Conduct the Ribbon Method.

A.   Take a ball of soil and gently push it into a ibbon between your thumb and forefinger. (as if you try to form a ribbon)

B.   If the soil does form a ribbon, just keep pushing the soil out until the ribbon breaks from its own weight.

C.   Distinguish whether it is Weak, Medium or Strong Ribbon.

Ø  Weak Ribbon- an inch or less before breaking

Ø  Medium Ribbon – one to two inches (1.0-2.0 in) before breaking

Ø  Strong Ribbon- longer than two inches (2 in)

 

7.    Operate Roll Method.

A.   Take a handful of soil and wet it so that it begins to stick together, but without sticking to your hand.

B.   Roll the soil sample for about 3 cm in diameter.

C.   Put the ball down – if it falls apart it is sand.

D.   If it sticks together, roll the ball into a sausage shape 6-7 cm long. If it does not remain in this form, it is loamy sand.

E.   If it remains in its shape, continue rolling until it reaches 15-16 cm long, if it does not remain in its shape then it is sandy loam.

F.    If it is still in shape, try to bend the sausage into a half circle, if not possible then it is a loam soil.

G.   Continue to bend the sausage to form full circle, if not it is heavy loam but if it can still continue then it is light clay

H.   Lastly, if the soil is still in shape then it is clay.

8.    Refer to the textural triangle.

 

·   Soil Structure

1.    Identify Soil Structure in every layer.

Ø  Grades of soil structure

o   0 Structureless has no observable aggregation or no definite orderly arrangement of natural lines of weakness, such as:

o   Massive structure (coherent) where the entire soil horizon appears cemented in one great mass;

o   Single-grain structure (non-coherent) where the individual soil particles show no tendency to cling together, such as pure sand;

Ø  Classes and Types of Soil Structure

·         Granular and Crumb structures are individual particles of sand, silt and clay grouped together in small, nearly spherical grains.

·         Blocky and sub-angular blocky structures are soil particles that cling together in nearly square or angular blocks having more or less sharp edges.

·         Prismatic and Columnar structures are soil particles which have formed into vertical columns or pillars separated by miniature, but definite, vertical cracks.

·         Platy structure is made up of soil particles aggregated in thin plates or sheets piled horizontally on one another. Plates often overlap, greatly impairing water circulation.

 

2.    Using the Classifications given above, observe and record the data gathered.

·    Soil Consistence

A.   Determination of wet-soil consistency

Press a small amount of wet soil between your thumb and forefinger to see if it will stick to your fingers. Then slowly open your fingers. Rate the stickiness as follows:

§  0 Non-sticky, if no soil or practically no soil sticks to your fingers;

§  1 Slightly sticky, if the soil begins to stick to your fingers but comes off one or the other cleanly and does not stretch when the fingers are opened;

§  2 Sticky, if the soil sticks to both the thumb and forefinger and tends to stretch a little and pull apart rather than pulling free from your fingers;

§  3 Very sticky, if the soil sticks firmly to both thumb and forefinger and stretches when the fingers are opened.

B.   Determination of moist-soil

Try to crush a small amount of moist soil by pressing it between your thumb and forefinger or by squeezing it in the palm of your hand. Rate moist soil consistency as follows:

§  0 Loose, if the soil is non-coherent (single-grain structure); 

§  1 Very friable, if the soil crushes easily under very gentle pressure but will stick together if pressed again;

§  2 Friable, if the soil crushes easily under gentle to moderate pressure;

§  3 Firm, if the soil crushes under moderate pressure but resistance is noticeable;

§  4 Very firm, if the soil crushes under strong pressure, but this is difficult to do between the thumb and forefinger;

§  5 Extremely firm, if the soil crushes only under very strong pressure, cannot be crushed between the thumb and forefinger, but must be broken apart bit by bit.

C.   Determination of dry-soil consistency

Try to break a small amount of dry soil by pressing it between your thumb and forefinger or by squeezing it in the palm of your hand. Rate dry soil consistency as follows:

§  0 Loose, if the soil is non-coherent (single-grain structure): 

§  1 Soft, if the soil is very weakly coherent and friable. breaking to powder or individual grains under very slight pressure;

§  2 Slightly hard, if the soil resists light pressure, but can be broken easily between thumb and forefinger;

§  3 Hard, if the soil resists moderate pressure, can barely be broken between the thumb and forefinger, but can be broken in the hands without difficulty;

§  Very hard, if the soil resists great pressure, cannot be broken between the thumb and forefinger but can be broken in the hands with difficulty;

§  Extremely hard, if the soil resists extreme pressure and cannot be broken in the hands.

D.   Record and tabulate the observed soil consistence in every layer of the soil sample.

 

III.           Determining Soil Chemical Characteristics

·   Determining Soil pH

1.    Using the Soil Test Kit, layout all the materials needed in the conduct of the Soil pH test such as test tubes, CPR, BCG, CPR, and color indicator chart.

2.    Fill the tube with soil sample to scratch the mark

3.    Add twelve (12) drops of CPR pH indicator dye.

4.    Mix by gently swirling the test tube 20 times

5.    Repeat step three (3) after about two (2) minutes and let the test tube stand for five (5) minutes

6.    To get the pH of the soil with the corresponding color chart of the pH indicator dye used.

7.    If the soil pH used to or greater than six (6) repeat steps 1 to 5 using BCG instead of CPR.

8.    Record the acquired data

9.    Wash test tubes with tap water then rinse with distilled water.

10. Repeat all the steps for each soil samples.

·   Determining soil Potassium level

1.    Using the Soil Test Kit, layout all the materials needed in the conduct of the Soil Potassium test such as test tubes, K, K1, K2.

2.    Fill the test tube up to the scratch mark with soil sample.

3.    Add 24 drops (or 1 ml) as solution K and 8 drops of solution K1.

4.    Mix well by gently swirling the tube for about 1 minute.

5.    Repeat step 3 after about 3 minutes and let stand for 5 minutes or until the soil particles have settled at the bottom of the tube.

6.    Add solution K2 as follows:

A.   Slowly insert the dropper containing 0.6 ml of solution K2 inside the test tube so that its tip is about 2 cm above the solution.

B.   Slowly add 12 drops of K2 one drop at a time

C.   Do not mix or shake the solution.

7.    Let it stand for 2 minutes. Then observe the appearance of a cloudy yellow layer on top of the orange solution. A distinct cloudy yellowish layer indicates that the soil has sufficient available potassium. There is no need to apply potassium fertilizer.

8.    If no distinct cloudy yellowish layer appears on top of the orange solution, the soil is deficient in available potassium. Refer to the table on fertilizer recommendation for different crops.

9.    Record the acquired data.

10. Repeat all the steps for every soil sample

·   Soil Phosphorus Test

1.    Using the Soil Test Kit, layout all the materials needed in the conduct of the Soil Phosphorus test such as test tubes, P, P1, and color indicator chart.

2.    Fill the test tube with the soil sample up to the scratch mark.

3.    Add 24 drops (or 1 ml) of solution P and 4 drops of solution P1.

4.    Mix well by gently swirling the tube for about 1 minute.

5.    Repeat step 3 after about 3 minutes and let the test tube stand for 3 minutes.

6.    Take one foil or tin strip and wrap it firmly at one end of the plastic stick.

7.    Without disturbing the soil, stir the solution slowly with the tin strip for 1 minute. Repeat the step for about 2 minutes. (Note: The tin strip attached to the plastic can be still used for another set of four samples provided that the analyses are done on the same day. Rinse the tin strip with distilled water after each analysis.)

8.    Match the blue color intensity of the solution with the color chart below and take note if the soil is low, medium or high in available phosphorus.

9.    Refer to the table on fertilizer recommendations for each crop.

10. Wash the test tube with tap water and then rinse with distilled water.

11. Record the acquired data

12. Repeat all the steps for every soil samples.

·    Soil Nitrogen Test

1.    Using the Soil Test Kit, layout all the materials needed in the conduct of the Soil Nitrogen test such as test tubes, N solution, and color indicator chart.

2.    Fill the test tube with soil sample up to the scratch mark.

3.    Add 24 drops (1 ml) of solution N.

4.    Mix well by gently swirling the test tube 30 times.

5.    Repeat step 3 after about 5 minutes and let the tube stand for 30 minutes.

6.    Match the color of the resulting solution on top of the soil with the color chart below and take note if the soil is low, medium, or high in available nitrogen.

7.    Refer to the table on fertilizer recommendation for different crops.

8.    Wash the test tube with tap water and then rinse with distilled water.

9.    Record the acquired data.

10. Repeat all the steps for every soil layer sample.

IV.          Determining Soil Biological Characteristics

·   Describing soil pores

1.    Observe visible roots present in every layer of the soil

2.    Measure the diameter of each roots present in every layer of the soil

3.    Categorize the measured roots by setting range of sizes from small, medium and large. (e.g. small 0.005-0.01, medium 0.02-0. 09 , large 0.1-0.5)

4.    Record and tabulate data.