Soils 101 Practice Exam 1

A It describes soils individually.

A soil pedon is _________________. A) A three-dimensional soil unit that embodies the primary characteristics of an individual soil B) Generally larger in area than a polypedon C) A nearly horizontal layer of soil that differs visibly from soil above and below D) A category of Soil Taxonomy E) A diagnostic horizon used to distinguish between soils of different orders

A Silt is smooth like flour, and sand is similar but a bit rougher than silt.

A soil that is very sticky when wet and very hard when dry likely contains a lot of ___________. A) Clay B) Sand C) Glue D) Silt E) Organic matter

A Difference between field capacity and wilting point.

According to the figure above, soil of which textural class has the largest plant available water holding capacity? A) Silt Loam B) Sandy Loam C) Clay D) Sand

B Rate of flow ALLOWS affect by pore size. Small pore size decreases rate of flow and large pore size increases rate of flow.

Because unsaturated flow in soils is driven by differences in matric potential the rate of unsaturated flow is not influenced by pore size. A) True B) False

A 10YR-Hue 3-Value 4-Chroma

In the Munsell color designation 10YR3/4 the hue is indicated by A) 10YR B) YR C) 3 D) 3/4 E) 4

A Paleud(ert)s. ert is in V(ert)isols. Vertisols have clay in them and when clay gets wet it expands, and when clay dries it shrinks. This can cause cracking and literally move the soil up and down. Think vertical movement to remember Vertisols.

In which of the soils listed below would you most likely find wide surface cracks during periods of dry weather? A) Paleuderts B) Kandiaquults C) Aquolls D) Ochraqualfs E) Albaqualfs

B Decreases macropore space.

Soil compaction decreases the amount of micropore space in a soil. A) True B) False

B Soil structure to form by freezing, animals burrowing, rainfall, etc. Microbes wrap around and strengthen soil structure otherwise this would not happen. It would happen very slowly by freezing, animals, etc. Soil fungal hyphae speeds up the process.

Soil fungal hyphae have an important influence on soil structure because they ___________. A) Actively form soil crusts B) Help to stabilize soil aggregates C) Create large bio-pores D) Help to flocculate soil colloids E) Dissolve sand grains

B Organic matter increases available water holding capacity.

Soils A and B are both surface horizon soils, both have silt loam texture and both have a bulk density of 1.2 Mg/m3. Soil A contains 1% organic matter and Soil B contains 3% organic matter by weight. Which soil likely has the greatest plant available water holding capacity? A) Plant available water holding capacity will be similar in Soils A and B. B) Soil B C) Soil A

E Relative amount of sand, silt and clay. Structure is how soil is put together for aggregates, this is DIFFERENT than texture.

The amount of different sizes of mineral particles in a soil defines the soil ____________. A) Value B) Profile C) Pore space D) Structure E) Texture

A Water into soil, matric forces decreases energy in water.

The attraction of water molecules to solid surfaces in soil decreases the potential energy of the water. A) True B) False

E E-Horizon is grey zone and orange zone contains Spodosols

The highly leached soil shown above developed under coniferous forest vegetation in coarse textured (sandy), acidic parent material. This soil would most likely be classified as which of the following orders? A) Alfisol B) Oxisol C) Andisol D) Mollisol E) Spodosol

B The soil is darker because of additional minerals from O-Horizon.

The master horizon designation for the dark colored mineral horizon indicated in the soil profile above is _____________ . A) O B) A C) C D) B E) E

B -1500 kPa is wilting point. Finer texture would increase water holding capacity.

The volume of water in soil at a moisture potential of -1500 kPa ________________________. A) Would be greater in a sandy soil than in a clayey soil B) Would be greater in a clayey soil than in a sandy soil C) Would be the same in a sandy soil as it is in a clayey soil

A Eutrud(ept)= Inc(ept)isols

To which soil order does the following soil belong; Fluventic Eutrudept? A) Inceptisols B) Vertisols C) Aridisols D) Ultisols E) Alfisols

A

What is the textural class of a soil with 20% clay, 40% silt, and 40% sand? A) Loam B) Silt loam C) Silty clay loam D) Loamy sand E) Sandy clay loam

C Saturated flow is driven by gravity. Osmotic is salt in the soil. A deals with Darcy's law and slows water flow. D deals with water going in/out of soil.

Which of the following factors would have the least influence on the rate of saturated water flow in soil? A) The tortuosity and connectivity of soil pores B) Water potential gradient C) Osmotic potential D) The size (radius) of soil pores

E O-Horizon is organic matter above the first mineral horizon (A). If mixed it would mix with A-Horizon and become Ap-Horizon. O-Horizon would be found in undisturbed forests

Which of the following horizons would not be found in a tilled corn field? A) E B) B C) A D) C E) O

D Glacial till is being deposited by glacials or moved by glacial. Colluvial is moved by gravity.

Which of the following is an example of water transported and deposited parent material? A) Glacial Till B) Residual C) Colluvial D) Alluvial

A Climate Biota Topography Parent Material Time

Which of the following is not considered one of the soil formation factors? A) Combustion B) Climate C) Biota D) Topography E) Parent materials

C Oxisols are found in very humid high temperature areas, very wet soil and they leech the soil. Wisconsin gets cold in the winters and the ground will freeze. Mollisols are found in grasslands, perfect for Iowa. Aridisols are found in dry desert, perfect for Nevada. Ultisols are found in very weathered places, perfect for S. Carolina. Alfisols are found in decusious forest, perfect for Pennsylvania.

Which of the following pairings is least likely? A) A Mollisol in Iowa B) An Aridisol in the Nevada C) An Oxisol in Wisconsin D) An Ultisol in South Carolina E) An Alfisol in Pennsylvania

C, B and D

Which of the following statements are true concerning saturated water flow in a well-structured soil? (Select all correct responses) A) Flow occurs primarily in water filled micropores. B) Flow is driven primarily by gravitational potential. C) Flow occurs primarily in water filled macropores. D) Flow is more rapid than unsaturated flow. E) Flow is driven primarily by matric potential. F) Flow is strongly influenced by osmotic potential.

A Plowing or compacting won't change TEXTURE. Texture is fixed. If soil pore size distribution, and soil structure were changed that would affect saturated flow.

Which soil characteristic is NOT affected by an increase in bulk density? A) Soil textural class B) Saturated flow rate C) Soil pore size distribution D) Soil structure

B Prismatic, Columnar and Sub-angular blocky are found in B-Horizon.

Which type of soil structure is typically found in A horizons? A) Prismatic B) Granular C) Columnar D) Sub-angular blocky

B Between rainfall events, roots have small contact w/ soil, it decreases chance at water. Water moves with unsaturated flow.

Plant roots obtain access to soil water primarily by root extension into moist soil. A) True B) False

B Without transporting Ex:Limestone, shale, sandstone

Residual parent materials are best described as ___________________. A) Materials formed under anaerobic conditions B) Materials formed by weathering of rocks and minerals in place. C) Materials removed by erosion from highly weathered soils D) Materials in upland locations with relatively little chemical weathering E) Materials transported by water, ice or wind