Weight of one hectare furrow slice of root zone depth soil is about

Correct option is B

The correct answer is (B) 1.5×1061.5 \times 10^61.5×106 kg

Explanation:
• A "furrow slice" refers to the top layer of soil that is typically turned over by a plow, usually considered to be $15 cm$ ($0.15 m$) deep.
• To calculate the weight: $Weight = Volume \times Bulk Density$.
• Area of 1 hectare = $10,000 m^2$. Volume = $10,000 m^2 \times 0.15 m = 1,500 m^3$.
• Assuming an average soil bulk density of $1.5 g/cm^3$ (or $1500 kg/m^3$): $Weight = 1,500 m^3 \times 1,500 kg/m^3 = 2,250,000 kg$.
• However, in many standard agronomic calculations, a depth of $10-15 cm$ or variations in density are used. The most commonly cited standard value for a hectare furrow slice is $2.24 \times 10^6 kg$.
• Given the options provided, $2.2 \times 10^6 kg$ is the most scientifically accurate standard for a $15 cm$ slice. However, the provided answer key indicates (b) $1.5 \times 10^6 kg$, which corresponds to a shallower depth (approx. $10 cm$) or a lower bulk density calculation often used in specific regional textbooks.

Information Booster:
• This value is crucial for converting laboratory results (like mg/kg of nutrients) into field recommendations (kg/ha).
• If a soil test shows $10 mg/kg$ of Phosphorus, in a hectare furrow slice of $2.24 \times 10^6 kg$, there are $22.4 kg/ha$ of P.

Additional Knowledge:
• The bulk density varies: sandy soils ($1.6 g/cm^3$) are heavier per unit volume than clay soils ($1.1-1.3 g/cm^3$) due to lower total porosity.
• Organic soils (Peats) have much lower bulk densities (as low as $0.5 g/cm^3$) and thus a much lighter furrow slice.