President Camacho awards a Golden Toupee to farmers that exceed the T value of t
ID: 298594 • Letter: P
Question
President Camacho awards a Golden Toupee to farmers that exceed the T value of their soil from water erosion (thus exposing better quality soil, according to him). Farmer Jane is thinking of applying – she wants a new look for her llama. Her soil, a loamy sand, has a T value of 10 Mg/ha/yr. Her farm has an area of 20 ha. She has lost 1 mm of soil per year for the last 10 years. A 1,000 cm3 sample of the top 20 cm of her soil had a wet weight of 1,400 g and a dry weight of 1,300 g.
24. What is the bulk density (in g/cm3 ) of the soil?
25. What is the volume of soil (in m3 ) lost from a 1-ha field in ten years?
26. What is the mass of soil (in Mg) lost from a 1-ha field in ten years?
27. Will Farmer Jane win the Golden Toupee?
28. How do you expect the capacity of the soil in Farmer Jane’s fields to change as a result of erosion?
29. How do you expect the pH buffering capacity of the surface soil Farmer Jane’s fields to change as a result of erosion?
30. Which of the following particle sizes distributions could correspons to Farmer Jane's soil
Explanation / Answer
24. What is the bulk density (in g/cm3 ) of the soil?
Soil bulk density = mass / volume (g/cm³)
Volume of top 20 cm soil = 1000 cm³
Dry weight of the soil top 20 cm soil = 1300 grm.
Bulk density of top 20 cm soil = 1300/1000 = 1.3 g/ cm³
The soil bulk or dry density, b, is the ratio of the mass of the solid phase of the soil (i.e., dried soil) to its total volume (solid and pore volumes together) and is defined as follows:
25. What is the volume of soil (in m3 ) lost from a 1-ha field in ten years?
Area of the farm = 20 ha = 200,000 sq.m. = 0.2 sq.km.
Soil loss = 1mm/year / 10 years = 10 mm = 0.01
Volume of soil lost in 20 ha = 200000 x 0.01 = 2000 cu.m.
Volume of soil lost in 1 ha in 10 years = 10000 x 0.01 = 100 cu.m.
26. What is the mass of soil (in Mg) lost from a 1-ha field in ten years?
Volume of soil lost in 1 ha in 10 years = 100 cu.m.
Bulk density of top soil = 1.3 g/cu.m.
Mass of the Soil lost from a 1 ha, field in 10 years = 100 x 1.3 = 130 Mg
Mass of the soil/ha/year = 130/10 = 13 Mg/ha/year
27. Will Farmer Jane win the Golden Toupee?
Yes Will Farmer Jane win the Golden Toupee as her Farm T = 13 Mg/ha/yr.
28. How do you expect the capacity of the soil in Farmer Jane’s fields to change as a result of erosion?
The fertility of soil decreases due to erosion. The soil erosion can be controlled by chaning crop, controlling run-off water, adding more soil etc.