Soil Science WEB Exam 6 - Fall 2007 Dept. of Soil, Water and Climate
Directions 1. There is ONE BEST answer per question. 2. Place your answers on answer sheet, you only need to turn in the answers.
Name______________________
1.________ 2._______ 3._________ 4._______ 5.______ 6._______ 7._________ 8._______
9.______ 10._______ 11. _________ 12.________ 13.______ 14.________ 15._________
Total _____
Soil Bulk Density -----------------------------------------------------------------------------------------------------------------------------
15 Questions
1. The bulk density (BD) of a soil is different from the particle density (PD) of a soil because ___?___
a) BD particles have a different weight than PD particles.
b) BD needs the volume of soil and PD needs the volume of the particles
c) BD needs the pore volume and PD needs the particle volume
d) BD needs the volume of soil pores and PD needs the volume of the soil
2. The weight of a graduated cylinder is 34 grams, the cylinder is filled with 60 ml of oven dry field soil. The weight of soil and cylinder is 108 grams. The bulk density of the soil is _____g/cc
a) 0.45 b) 1.15 c) 1.23 d) 1.41
3. For question 2, the 60 ml sample of soil is filled with water. The water is poured carefully into the cylinder until all the air pores are filled with water. The amount of water that this would take is about ______. (Assume PD=2.65g/cc)
a) 28 ml b) 32 ml c) 34 ml d) 37 ml
4. A soil clod is fixed with plastic to make it rigid when placed in water. The weight of the clod in air is 154 g and the weight in water is 39 g. The bulk density of the clod is ____.
a) 0.94 g/cc b) 1.24 g/cc c) 1.34 g/cc d) 1.44 g/cc
5. A soil core is taken from a field and oven dried. The core radius is 2.5 cm and the height is 6 cm. The weight of the core is 23 grams. The weight of the core and oven dry soil is 244 g. The bulk density of the soil is _____. ---(core vol=Pi × r² ×h)
a) 0.96 g/cc b) 1.07 g/cc c) 1.76g/cc d) 1.88 g/cc
6. You have a very light styrofoam box that you fill with soil from your garden. You place the box in the garage and forget about it for a few months during the summer. The garage is pretty hot and the soil eventually is air dry. You later pick up the box and determine the box and soil weighs about 25 lbs. What is the bulk density of the soil? Box Vol.=(A=14 in. B=8 in. C=5 in.)
a) 77 lbs/ft 3 b) 80 lbs/ft 3 c) 83 lbs/ft 3 d) 132 lbs/ft 3
7. What is the bulk density of the soil in question 6 in grams per cubic centimeter. (BD of water is 62.4 lbs/ft3)
a) < 0.9 g/cc b) between 1.00 and 1.20g/cc
c) between 1.21 and 1.50 d) >1.51 g/cc
8. You determine that a soil sample has a BD of 0.3 g/cc (or Mg/M3 ). This means that the soil______
a) has been oven dried
b) has been cultivated
c) is developed from volcanic lava or basalt rock.
d) is from an organic soil (histic epipedon) of moderate decomposition.
9. You need to purchase some black "SOIL" for topsoil to place in your front yard. A local farmer sells it by the "field condition" ton (soil contains some water or it is called "wet" not oven dry). You determine your yard and is 105 feet wide and 100 feet long. You decide that topsoil 4 inches deep should be adequate for your ornamental plants and turf. If the bulk density of the farmer's soil is 1.65 g/cc, how many "wet" tons should you buy?
a) 1.8 tons b) 18 tons c) 180 tons d) 1800 tons
10. The same farmer indicated that in their corn fields the local soil conservation officer said the soil erosion was about 20 tons per acre in the past year, how many inches of topsoil have been lost per acre/year. The oven dry bulk density is 1.36 g/cc. ( One acre=43560 sq. ft. )
a) 0.13 inch b) 0.23 inch c) 0.33 inch d) 0.43 inches
11. The compactor in the picture will ___?___ of the soil and thus ___?____.
a) increase bulk density .....improve bearing capacity.
b) decrease the bulk density and improve water infiltration
c) increase bulk density....... .increase porosity .
d) smooth the surface .....make it easier to construct a building.
12. The main objective of tillage in this
picture is to __?__
a) lift and turn the soil so the plant residue is covered and thus the dark soil will aid in increased soil temperature.
b) mix the soil only in a strip (at the planting row), while leaving plant residues on the surface between the rows to protect the soil
c) increase the soils porosity over the entire field.
d) promote a very loose soil surface to aid in root and water movement.
13. The diagram for this question shows a constructed wetland for sewage treatment that is the___?___
a) Subsurface flow system.
b) Free Water System
c) Aquatic Plants System
d) Septic tank system.
14. Soil temperature regimes in the USA go from Frigid in the north to Hyperthermic in the far south. States like Iowa are mostly __?__ while states like Mississippi are mostly __?__
a) Frigid and Hyperthermic.
b) Mesic and Thermic.
c) Thermic and Hyperthermic
d) Cryic and Frigid.
15. The equipment shown here is for ________
a) compacting the soil prior to construction.
b) turf tillage of athletic fields.
c) mixing the soil with minimal incorporation of plant .
d) preparing the soil for no-till planting.
