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In the case of any two of the following describe a laboratory or field method: (a) To determine the percentage mineral ash in a sample of freshly cut grass - Leaving Cert Agricultural Science - Question 4 - 2015
Question 4
In the case of any two of the following describe a laboratory or field method: (a) To determine the percentage mineral ash in a sample of freshly cut grass. (b) To... show full transcript
Worked Solution & Example Answer:In the case of any two of the following describe a laboratory or field method: (a) To determine the percentage mineral ash in a sample of freshly cut grass - Leaving Cert Agricultural Science - Question 4 - 2015
Step 1
To determine the percentage mineral ash in a sample of freshly cut grass.
Answer
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Sample Preparation: Begin by collecting a representative sample of freshly cut grass, ensuring it is free from soil and other contaminants.
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Weighing: Weigh the empty crucible and record its mass. Then, add the grass sample to the crucible and weigh it again.
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Calculation: Calculate the mass of the grass sample by subtracting the mass of the empty crucible from the total mass.
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Ashing Process: Place the crucible with the grass sample in a muffle furnace. Set the furnace to a temperature around 550°C and gently burn the sample to a constant mass. This process will lead to the complete combustion of the organic matter, leaving behind the mineral ash.
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Final Weighing: After cooling, weigh the crucible with the remaining ash. Subtract the mass of the empty crucible to find the mass of the mineral ash.
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Percentage Calculation: Finally, calculate the percentage of mineral ash in the sample using the formula: ext{Percentage Mineral Ash} = rac{ ext{Mass of Ash}}{ ext{Mass of Grass Sample}} imes 100
Step 2
To assess the effects of overgrazing on the botanical composition of a pasture sward.
Answer
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Site Selection: Select two areas of equal size within the pasture: one area that has been grazed normally and another that has been overgrazed.
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Sampling Method: Use a quadrat method for sampling. Randomly place quadrats in both areas to record the plant species present.
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Data Recording: Record the different plant species and their abundance in each quadrat for both the normally grazed and overgrazed areas.
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Comparison: Analyze and compare the botanical composition between the two areas, noting differences in species richness, diversity, and dominance.
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Interpretation: Discuss the effects of overgrazing on plant community structure and biodiversity, providing insights into the impact of grazing management on pasture health.