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Describe a laboratory or field method to determine any two of the following: (a) The texture of a sample of wet soil - Leaving Cert Agricultural Science - Question 4 - 2010
Question 4
Describe a laboratory or field method to determine any two of the following: (a) The texture of a sample of wet soil. (b) The number of earthworms in a pasture. (... show full transcript
Worked Solution & Example Answer:Describe a laboratory or field method to determine any two of the following: (a) The texture of a sample of wet soil - Leaving Cert Agricultural Science - Question 4 - 2010
Step 1
The texture of a sample of wet soil.
Answer
To determine the texture of a wet soil sample, first dry a portion of the soil in an oven and crush it. Then weigh the dried soil. Next, place the soil in a sieve with different mesh sizes to separate it into particle size categories such as sand, silt, and clay. Allow it to settle, and measure the mass of the soil retained in each sieve.
Finally, calculate the percentages of each size fraction relative to the total mass of the dried soil to ascertain the soil texture. A textural triangle can then be used to classify the soil based on the relative proportions of sand, silt, and clay.
Step 2
The number of earthworms in a pasture.
Answer
To assess the number of earthworms in a pasture, mark out areas in a quadrat measuring square meters. Use a diluted detergent solution or an alternative to extract the earthworms from the soil. Slowly water the marked areas for a period, typically around 15 minutes, to encourage earthworms to come to the surface.
Then, collect and count the number of earthworms present in the quadrat. Finally, extrapolate the results by calculating the number of earthworms per square meter over the entire area, using a conversion factor if the overall pasture area is larger.