Waec Model Questions Vol1 2020 Agricultural Science Question 2

Practice practical question 2 from the 2020 Waec Model Questions Vol1 Agricultural Science examination. This question covers Soil Science, Soil pH, Liming .

Waec Model Questions Vol1 2020 Agricultural Science Practical

Topics: Soil Science Soil pH Liming

Question 2 WAEC_MODEL_QUESTIONS_VOL1 • 2020 • AGRICULTURAL_SCIENCE • practical

A soil scientist is evaluating the lime requirement for an acidic loamy soil in a wheat field. The target pH for optimal wheat growth is 6.5. The current soil pH measured with a calibrated pH meter is 5.2. The soil's buffer capacity, determined by a laboratory titration, is 2.5 meq · 100 g⁻¹. The bulk density of the soil is 1.3 g cm⁻³ and the plough layer depth is 15 cm.

Question Parts

( a )

Outline the practical steps for collecting a representative soil sample from the field and preparing it for pH measurement with a digital pH meter.

( b )

Using the data provided, calculate the amount of agricultural lime (CaCO₃) required per hectare to raise the soil pH from 5.2 to 6.5. Assume the relationship: Lime requirement (kg ha⁻¹) = [(Target pH – Current pH) × 1000] ÷ Buffer capacity (meq · 100 g⁻¹) × Soil weight per hectare (kg). Soil weight per hectare = bulk density × plough depth × 10,000 m² × 1,000 kg m⁻³.

( c )

Explain two agronomic implications of applying the calculated amount of lime to the field.

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About This Question

This is Waec Model Questions Vol1 2020 Agricultural Science Question 2. It is one of the practical questions from the 2020 Waec Model Questions Vol1 Agricultural Science examination.

The question covers Soil Science, Soil pH, Liming .

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