K.C.S.E AGRICULTURE Q & A - MODEL 2018PP1QN016

​An experiment was carried out to investigate soil constituents as described below:

• Step 1 — An empty evaporating dish was weighed and its mass was lOgms. ‘
• Step 11 — Fresh garden soil was put on the evaporating dish and weighed. The mass was 4ogms.
• Step III — The evaporating dish containing fresh soil was put in an oven and heated at a temperature of 105 °C for 30 minutes, cooled and then weighed. The mass was 35gms.
• Step IV — The dish containing soil was then strongly heated on a Bunsen burner for two hours while stirring. It was then cooled and weighed. The new mass was 32 gms.

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Give a reason why the soil was heated

• At 105°C
• Strongly for two hours

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Answer

• Get rid of soil moisture;
•  Destroy soil organic matter;

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​Calculate the percentage content of the soil constituents investigated in the experiment

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