SOIL 153 Unit 2 Quizzes

Which soil textural classes will be more prone to nutrient deficiency for plants?

Coarse soil textures, because they have lower clay contents and less negatively charged surface area which corresponds to a smaller amount of nutrient cations per kilogram of soil

Which soil textural types may be more susceptible to ground water pollution (e.g. by nitrogen fertilizers)?

Coarse textures, because they have a lower CEC and greater hydraulic conductivity (permeability) than finer textures

There are multiple ways that salt-affected soils may form. Which of the following describes a scenario prone to salt build-up

High water tables

The process indicated by arrow 1 on the above diagram of the N cycle is ...

mineralization

Which of the following pH values would indicate and acidic soil condition?

pH = 6.2

What does ESP measure?

percent of exchangeable cations that are sodium (Na+)

To which box would you connect for the addition of manure or composts used as a fertilizer?

Organic Matter

Which box represents where the greatest amount of soil nitrogen is stored?

Organic matter

_____ is when a root grows to the nutrient in the soil

Root extension

Match the salt- affected soils to their problem

Saline- Excess soluble salt Saline-Sodic- Excess soluble salt and exchangeable sodium Sodic- Excess exchangeable sodium Non-salt affected soils- There is no excess of anything

The total amount of negative charge in the soil solids is measured by how many cations the soil can hold and is called

cation exchange capacity

Which of the following soils would be expected to have the greatest pH buffering capacity

high amount of clay

The process occurring by arrow(s) 2 in the above diagram of the N cycle is ...

immobilization

Composting results in the volume fo the composting material being ____ and the C:N ration of the material being ____

reduced, reduced

For soils, the buffering capacity relates to the ability of the soil to

resist a change in pH

The process of decomposition of organic materials in soil can be written as a chemical formula that closely resembles the formula for

respiration

To which box would you connect for the addition of gaseous anhydrous ammonia used as a fertilizer?

soil solution

Which form of nitrogen fertilizer (NH4+ or NO3-) would be expected to be found i surface waters (streams and lakes) if erosion occurs?

Ammonium (NH4+) because it is a cation and is attracted to the negatively charged soil particles

The ability of soil to resist or counteract a change in pH is known as the soil buffering capacity. Since most of the H+ and Al3+ present in a soil exists as exchangeable or 'reserve' acidity, the extent of a soils buffering capacity is closely correlated with the CEC of that soil. Estimate the cation exchange capacity (CEC) of each soil listed below, then rank their pH buffering capacities from highest (at the top) to lowest (on the bottom). Average CEC of clay in Central Plains = 80 cmolc/kg Average CEC of soil organic matter = 200 cmolc/kg

1- clay = 5% and soil organic matter = 35% 2- clay = 35% and soil organic matter = 2% 3- clay = 22% and soil organic matter = 6% 4- clay = 15% and soil organic matter = 3.5% 5- clay = 18% and soil organic matter = 1%

Using the C:N ratio in calculations. The situation: We have an organic residue pile (300 lbs dry weight) made up of deciduous tree leaves. The carbon content of the residue (leaves) is 50%, and the C:N ratio = 60. Under ideal decomposition, 40% of the organic carbon becomes humus (or compost) which has a C:N ratio = 15. The nitrogen (N) content of residue influences how much carbon will be efficiently decomposed. Given the N content of these leaves, calculate the mass of C that can efficiently become compost.

37.5

Using the C:N ratio in calculations. The situation: We have an organic residue pile (300 lbs dry weight) made up of deciduous tree leaves. The carbon content of the residue (leaves) is 50%, and the C:N ratio = 60. Under ideal decomposition, 40% of the organic carbon becomes humus (or compost) which has a C:N ratio = 15. The nitrogen (N) content of residue influences how much carbon will be efficiently decomposed. Calculate the mass of C that would be converted to compost under ideal conditions.

60

Nitrification occurs fastest under which of the following conditions?

Aerobic soils, pH 7.5

Match the 'Organism Functional Group' with the 'Examples of Organisms' that would belong to that functional group.

Bacterial and fungal feeders (aka Grazers) Protozoa, Nematodes, and Microarthropods Mutualists Rhizobium Bacteria and Mycorrhizal Fungi Shredders Earthworms and Macroarthropods Pathogens and Parasites Bacteria, Fungi, Nematodes, and Microarthropods Primary Decomposers Bacteria, Fungi, and Actinomycetes Root-Feeders Nematodes and Microarthropods Higher-Level Predators Predatory Nematodes, Larger Macroarthropods, Small Mammals

Peak decomposition occurs at...

C:N ratio of 10

Which arrow represents nutrient release from decomposition of dead plants?

D

Considering what you now know about pH buffering capacity of soils and how it is related to properties of soil texture, clay mineral type, humus content, reserve acidity, and the amount of lime required for pH adjustment, select four of the following that are TRUE statements.

-Sandy soil has a lower buffering capacity as compared ot a clayey soil -If all other factors are equal, a coarse textured soil will acidify faster than a medium or fine textured soil -Soils with a higher buffering capacity will require more lime to be added to get a change in the pH -Increasing organic matter content will increase the buffering capacity of a soil

Four soils of different textural classes were sampled from different locations and were tested for solution pH. All four soils were found to have a solution pH of exactly 5.0. Two tons of lime per acre were applied to each of the four soils and incorporated with similar tillage operations at each location. The soil pH values taken one year after the addition of the lime are given below. Rank the soils from greatest (1) to least (4) pH buffering capacity:

1- pH 5.4 2- pH 5.8 3- pH 6.2 4- pH 6.7

Choose three statements below, selecting one statement that accurately describes each of the following: How the amount of CO2 produced from a soil by OM decomposition responds to increasing temperature over time. How the amount of NO3- accumulated responds with soil temperature over time. How the temperature of the soil affects the amount or rate of organic matter decomposition by soil microorganisms.

1. CO2 Evolution vs Time The amount of CO2 evolved from soil in the NCSoil Model increased with increasing temperature, in a direct type of relationship. 2. NO3- Evolution vs Time The amount of NO3- evolved from soil in the NCSoil Model increased with increasing temperature, in a direct type of relationship. 3. General effect of soil temperature on OM decomposition and available N: Decomposition of organic matter in soils increases with increasing temperature, and results in greater amounts of CO2 evolution and available mineral N accumulation.

Suppose we have manure (500 lbs dry weight) applied as fertilizer on a small organic farm growing sweet corn and other vegetables. The applied manure has a C:N ratio of 20, with carbon content of 45%. Typically, organic materials applied to soil have an efficiency of 40% in turning carbon from raw materials into humus (C:N =10), with 60% of C lost as CO2. Use the information given to calculate the following:How much N (lbs) is in the applied raw materials (manure)?

11.3

According to the Course Manual Notes, how many elements are deemed 'essential' for plant growth

16

Suppose we have manure (500 lbs dry weight) applied as fertilizer on a small organic farm growing sweet corn and other vegetables. The applied manure has a C:N ratio of 20, with carbon content of 45%. Typically, organic materials applied to soil have an efficiency of 40% in turning carbon from raw materials into humus (C:N =10), with 60% of C lost as CO2. Use the information given to calculate the following:How much C (lbs) is in the raw material (manure)?

225

A C:N ratio where the processes of N immobilization and N mineralization are occurring at about the same rate is near

25:1

Suppose we have manure (500 lbs dry weight) applied as fertilizer on a small organic farm growing sweet corn and other vegetables. The applied manure has a C:N ratio of 20, with carbon content of 45%. Typically, soil microorganisms decomposing organic materials applied to soil have an efficiency of 40% in transforming carbon from raw materials into humus (C:N =10), with 60% of the C in the raw materials lost as CO2 gas. Use the information given to calculate the following:How many pounds of the Carbon in the applied manure is potentially converted into humus?

90

Which arrow represents the dissolution of calcium ions from lime?

A

Match the following descriptions or definitions with its correct term.

A species of bacteria which infect roots and fixes Nitrogen from the atmosphere into organic form- Rhizobium Organisms that live at the expense of other organisms while providing no benefits in return- Parasites Organisms that cause or promote disease in other organisms or plants- Pathogens A type of fungi that engages in symbiotic relationship with the roots of plants- Mycorrhizae The region of increased biological activity immediately adjacent to a live plant root- Rhizosphere Organisms that directly consume organic residues, e.g. bacteria, actinomycetes, and fungi- Primary decomposers

A grower has a 5-acre upland spot in a field on which he says crops do not do as well as in compared to the rest of the field. He says he has tried everything to improve this spot without success. He is convinced the soil in this spot is "alkali" (common term for salt-affected soils). He describes the field in question as follows: The slope is about 4% and the soil class is silt loam. According to the soil survey report, the soil is underlain to a depth of about 20 feet by permeable loess. According to a soil test he had done three years ago, the soil pH is 6.5 and the organic matter content is 1.8%. No saline-sodic soil test has been done. Which of the above conditions could be cited as counter-arguments to the growers claim of 'alkali' soils? Select four of the statements below that apply.

According to the soil survey report, the soil is underlain to a depth of about 20 ft by permeable loess According to a soil test he had done three years ago, the soil pH is 6.5 The slope is about 4% and soil class is silt loam A 5-acre upland spot

Consider the summaraized soil test report for a field in Northeastern NEbraska sampled for pH and nutrients (below) What is the average % acid saturation and % base saturation for this field?

Acid % = 55.8 Base % = 43.8

A soil tested at a laboratory returns the following results: CEC = 18 cmolc/kg Base saturation = 80% Exchangeable Ca2+ = 11 cmolc/kg Use the information provided to calculate the following and select the correct answers from the choices below: Acid Saturation (%) Exchangeable acidity (cmolc/kg) Ca Saturation (%)

Acid Saturation = 20% Exchangeable acidity = 3.6 cmolc/kg Ca saturation = 61%

A diversion canal, installed in 1933 and belonging to a power company, runs along the uphill side of a farmer's field. The land in the field is nearly level. The farmer claims that seepage from the canal has raised the water table in the field and made his field "alkali." He has noticed problems with plant growth only within the last few years. A soil test of the field shows EC = 2.86 and SAR = 18. Which of the following is a viable option for the farmer to take in managing this land?

Add CaSO4 and organic matter, improve drainage and leaching

For the following statements, match the answer that creates a true statement about optimal conditions for soil microorganism activities.

Aerobic organisms would prefer a water potential of about _______________ KPa. -33 Anaerobic organisms would prefer a water potential of about _____________ KPa zero The optimum temperature range for most soil microorganisms is about _______________ degrees C. 20 to 40 The optimum pH range for most soil microorganisms is about pH = ______________ . 6.5 to 7.2 Generally the _____________ are able to tolerate lower soil pH conditions than other organisms. fungi The _________________ become inactive at lower soil pH conditions (e.g. pH less than 5.5). bacteria For soil microorganisms, the maximum amount of biological activity is expected to occur at a soil temperature of ________ degrees C. 30 to 35

Match the following cations to their chemical formulas

Ammonium- NH4+ Potassium- K+ Calcium- Ca++ Magnesium- Mg++

Denitrification rates are expected to be greatest under which of the following conditions?

Anaerobic (saturated) soil

Which arrow represents the formation of an insoluble phosphorus compound?

B

Two colored ions (blue and orange) were mixed at equal concentrations to form a purple solution. When this solution was added to a sandy soil, the color of leachate (solution coming out the bottom) remained purple. However, when the solution was added instead to a dark colored clay loam soil, the color of leachate was orange. Which ion is positively charged?

Blue ions

A soil test confirms that a soil contains the following amounts of cations: Ca2+ = 13 cmolc/kg Mg2+ = 4 cmolc/kg K+ = 1 cmolc/kg Na+ = 1 cmolc/kg H+ = 5 cmolc/kg Al3+ = 3 cmolc/kg The soil test showed no other exchangeable cations present on the soil. Find the following quantities:

CEC ( cmolc/kg)=27 H saturation (%)=18.5 Ca saturation (%)=48.1 Na saturation (%)=3.7 Mg saturation (%)=14.8 TEB (cmolc/kg)=19 K saturation (%)=3.7 Base saturation (%)=70.4

Match how the soil pH would change due to the application of the following compounds:

Calcium carbonate (CaCO3) - Increase Large amounts of ammonium based fertilizer- Decrease

Using the C:N ratio in calculations. The situation: We have an organic residue pile (300 lbs dry weight) made up of deciduous tree leaves. The carbon content of the residue (leaves) is 50%, and the C:N ratio = 60. Under ideal decomposition, 40% of the organic carbon become humus (or compost) which has a C:N ratio = 15. The nitrogen (N) content of residue influences how much carbon will be efficiently decomposed. Following one growing season, some decomposition has occurred. In which C pools would carbon from the leaves be expected to found after one growing season.

Carbon Dioxide, Organic C in leaves, Humus/Compost

The C:N ration relates what two aspects of plant residue?

Carbon and Nitrogen

From the list below, identify eight nutrients taken up as cations by plants.

Copper, Manganese, Nitrogen, Calcium, Zinc, Magnesium, Potassium, Iron

Select four soil conditions that result form high levels of soluble salts in the soil

Create negative osmotic potential in the soil Increase the amount of unavailable water in a soil Increase the volumetric water content at wilting point Make the total water potential in the soil more negative

Select four of the following statements that are TRUE regarding the effects of high levels of exchangeable sodium ions in soil?

Creates a strongly alkaline pH Reduces soil permeability Causes aggregates to disperse Contributes to surface crusting

The graph above shows cumulative CO2 evolved from soil over 180 days at 60% and 80% WFPS. The reason for the difference in CO2 evolved from the 80% WFPS soil compared to the 60% WFPS soil is ...

Decomposition is aeration limited at 80% WFPS.

_______ is a microbial process that converts nitrate to gaseous forms. This process ______ the amount of plant available nitrogen

Denitrification, decreases

Which of the following soils classify as saline? Select all that apply

EC= 5.8 SAR= 8 pH = 7.4 EC= 4.2 SAR = 15 pH = 8.7 EC = 6.5 SAR = 11 pH = 7.5

The soil test used to measure the amount of soluble salts present in the soil solution is:

Electrical conductivity

Which letter in the image above shows nutrient release from CEC?

F

Select three of the following actions or environments that increase soil acidity by addition of H+

Growth of roots Use of ammonium fertilizers Rain water passing through the soil

The soil acidic cations are

H+ , Al^3+

Soil pH is a measure of which of the following?

H+ ion concentration in the soil solution

Total soil acidity includes the dissolved H+ and exchangeable acidity. Which ions contribute to exchangeable acidity?

H+, Al^3+

Select three of the following actions or environments that increase soil acidity by removal of soil bases

Heavy rainfall environment Animals grazing forage crops Growth of plant roots

______ is where mineral forms of nitrogen (ex. nitrate and ammonia) are incorporated into organic materials (ex. microbial cells and humus) This process ___ the amount of plant available nitrogen

Immobilization, decreases

A gardener bought 20 acres of bottomland last August. As she examined the soil late this spring she found that "there was some kind of white gunk on the soil surface" and that the soil seemed to dry out very slowly. The field is very level and relatively high in organic matter. She has asked you whether there might be a problem here when she starts growing vegetables next year. You have gotten a soil test (good idea) and have found that the EC is 7.4 dS/m, the soil pH is 8.4, and the SAR is 5. From an examination of the site (also a good idea) you find that the water table, which is established by the river about 3/4 mile away, is now (May) about 2 feet below the surface. What is a likely impact of this soils current condition?

Lack of available water for plants

_____ is the loss of nitrate downward through the profile This process decreases the amount of plant available nitrogen

Leaching, decreases

The graphs above show nitrate accumulation versus time at different water filled pore space levels. Why is the amount of soil NO3- accumulated in the 40% WFPS graph less than the amount in the 60% WFPS graph?

Mineralization and nitrification are water-limited at 40% WFPS compared to 60%.

The graphs above show nitrate accumulation versus time under different residue rates. Overall, the process(es) that combine to increase the nitrate accumulation (NO3-) over time are ...

Mineralization followed by nitrification

_____ is the process that converts an organic form of a nutrient to an inorganic form. This process _____ the amount of plant available nitrogen

Mineralization, increases

Match the names of the Type of Organism with the best description of the Organism Group that fits it.

Mostly single-celled and very numerous in soils Bacteria These are predatory on the other groups of organisms, especially bacteria. Protozoans Single or Multi-celled organisms with hyphae Fungi, yeasts, and molds A highly varied group of non-segmented worms Nematodes These activities of these 'mixers' of the soil enhances soil structure Earthworms Living near the surface, these organisms shred organic materials, increasing surface area and hastening decomposition Arthropods Organisms that use solar energy to fix atmospheric CO2 into biomass Algae

If Nitrogen fertilizer is applied to a soil over many years, which form of N would be expected to be found in the ground water beneath that soil?

Nitrate (NO3-) because it is an anion and is not attracted to the negatively charged soil particles

Match the following anions to their chemical formulas

Nitrate- NO3- Monophosphate- H2PO4- Sulfate- SO42- Diphosphate- HPO42-

______ is a microbial process that brings atmospheric nitrogen gas (N2) into the soil. Can be done symbiotically (with a host plant) or non-symbiotically The process ______ the amount of plant available nitrogen

Nitrogen fixation, increases

A grower has a 5-acre upland spot in a field on which he says crops do not do as well as in compared to the rest of the field. He says he has tried everything to improve this spot without success. He is convinced the soil in this spot is "alkali" (common term for salt-affected soils). He describes the field in question as follows: The slope is about 4% and the soil class is silt loam. According to the soil survey report, the soil is underlain to a depth of about 20 feet by permeable loess. According to a soil test he had done three years ago, the soil pH is 6.5 and the organic matter content is 1.8%. No saline-sodic soil test has been done. What is the likely condition of this field?

Non-saline

The graph above shows the soil carbon dioxide accumulation versus time under different residue rates. Where does the CO2 come from in the 0 tons/acre applied residue treatment?

OM already in the soil

For the following, match the potential information desired with the type of measurement that is likely to provide it.

Organism type or group that may be active or inhibited. Soil pH (acidity level) The relative rate of current biological activity in the soil compared with the maximum rate. Soil temperature The relative level (amount) of current biological activity compared with the maximum expected biological activity. Soil water potential (kPa) The current amount of respiration by soil organisms, and the overall level of biological activity in the soil. Soil CO2 flux

A gardener bought 20 acres of bottomland last August. As she examined the soil late this spring she found that "there was some kind of white gunk on the soil surface" and that the soil seemed to dry out very slowly. The field is very level and relatively high in organic matter. She has asked you whether there might be a problem here when she starts growing vegetables next year. You have gotten a soil test (good idea) and have found that the EC is 7.4 dS/m, the soil pH is 8.4, and the SAR is 5. From an examination of the site (also a good idea) you find that the water table, which is established by the river about 3/4 mile away, is now (May) about 2 feet below the surface. What is the likely condition of this soil as indicated by the soil test?

Saline

What is the correct term for the process by which water-soluble salts accumulate in the soil?

Salinization

For each of the following samples, match their C:N ratio and expected impact on soil mineral N supply (net mineralization or immobilization).

Sample 1 C:N = 63, Net Immobilization Sample 2 C:N = 79, Net Immobilization Sample 3 C:N = 19, Net Mineralization Sample 4 C:N = 16, Net Mineralization

Estimate the charges of the soils described in the table below then match the charge amounts with their corresponding soil textures from the options listed

Sandy Loam= 7 Silty Clay= 44 Silty Clay Loam= 37 Loam= 35 Silt Loam= 22 Clay= 10

A diversion canal, installed in 1933 and belonging to a power company, runs along the uphill side of a farmer's field. The land in the field is nearly level. The farmer claims that seepage from the canal has raised the water table in the field and made his field "alkali." He has noticed problems with plant growth only within the last few years. A soil test of the field shows EC = 2.86 and SAR = 18. What is the condition of the soil in this field?

Sodic

To which box would you connect for the loss of nutrients due to leaching?

Soil Solution

Which of the following conditions would be most favorable for aerobic biological activity?

Soil Water Potential of -50 kPa

Which of the following conditions would be expected to be the most favorable (optimum) for soil biological activity?

Soil temperature of 30 degrees C

When comparing rates of decomposition, which of the following would be considered as environmental cariables?

Soil temperature, Moisture status

From the list below, identify five nutrients taken up as anions by plants.

Sulfur, Boron, Molybdenum, Chlorine, Nitrogen

Match the "Described Organism" with the benefit it receives from the symbiotic relationship. Hint: The host is the larger organism; the hosted organism lives within the host organism.

The algal cell in a 'Lichen' receives shelter and mineral nutrients from the host organism The fungal organism of a Lichen receives 'food' (chemical energy) from the hosted organism rhizobium bacteria in symbiotic nitrogen fixation receives water, food (chemical energy), and shelter from the host organism A legume plant in symbiotic Nitrogen fixation receives nutrients from the hosted organism A Plant root engaged with a mycorrhizal fungi receives water and nutrients from the hosted organism a mycorrhizal fungi colonized with a plant root receives food (chemical energy) from the host organism

What is WFPS

The fraction of soil pore space filled with water

In natural and managed soil ecosystems, growing plants derive most needed nutrients from...

The remains of dead plants that are decomposing in the soil

Using the C:N ratio in calculations. The situation: We have an organic residue pile (300 lbs dry weight) made up of deciduous tree leaves. The carbon content of the residue (leaves) is 50%, and the C:N ratio = 60. Under ideal decomposition, 40% of the organic carbon become humus (or compost) which has a C:N ratio = 15. The nitrogen (N) content of residue influences how much carbon will be efficiently decomposed. Use the information given above to determine the following and then match the answers to the correct quantities listed below. Total mass of raw material (leaves): ___________ pounds Mass of carbon in the raw material: ___________ pounds C:N of the raw material: _______________ Mass of nitrogen in the raw material: ___________ pounds

Total mass of raw material (leaves): 300 Mass of carbon in the raw material: 150 C:N of the raw material: 60 Mass of nitrogen in the raw material: 2.5

Which of the following statements explain why the relative soil microbial activity is greatest (peaks) at 60% WFPS? Select two.

WFPS less than 60% is water-limiting to soil microbial activity. WFPS greater than 60% is aeration limiting to soil microbial activity.

A diversion canal, installed in 1933 and belonging to a power company, runs along the uphill side of a farmer's field. The land in the field is nearly level. The farmer claims that seepage from the canal has raised the water table in the field and made his field "alkali." He has noticed problems with plant growth only within the last few years. A soil test of the field shows EC = 2.86 and SAR = 18. Is the presence of the canal a possible cause of the problem?

Yes

The process indicated by arrow 4 in the above diagram of the N cycle is ...

aerobic

The form of N in soil that can be bound to CEC and also used by plants is ...

ammonium (NH4+)

Match the relationship description to the 'Description of Organisms' involved in the relationship.

an algal cell living inside of a fungal organism Symbiotic 'Lichen' Rhizobium bacterium living inside the root nodules of legume plants Symbiotic Nitrogen Fixation various types of fungi that colonize in or on the roots of most plant species. Mycorrhizae the site of relatively intense biological activity in the narrow (~2 mm) region immediately adjacent to a live plant root. Rhizosphere

The process indicated by arrow 6 in the above diagram of the N cycle is ...

anaerobic

As a general rule, ___ move through the soil more easily than ____

anions, cations

In chemistry, the term organic refers to any substance that contains the element

carbon

Organic matter is anything that once lived. As such, soil, organic matter is dominantly composed of ____.

carbon

In soil, nutrient mobility is likely to be greatest in

coarse, sandy textures

Primary Producers fix CO2 from the atmosphere . This is primarily done by plants, algae, photosynthetic bacteria .

fix CO2 from the atmosphere, plants, algae, photosynthetic bacteria

The products in boxes 9 and 11 on the above diagram of the N cycle are ____________ N forms.

gaseous

In soil, plant nutrients would be expected to have greater mobility in a fine textured soil with ____

good structure (well-aggregated soil)

Sodic soils are commonly treated with

gypsum

Which of the following are TRUE regarding soil organic matter in soils?

includes living organisms (e.g. fungi, bacteria, and invertebrates). includes waste materials excreted by living soil organisms. includes both 'active' and 'stable' forms

Nutrient mobility in soil is a function of its chemical nature - including ionic charge, solubility in water, and reaction to acidity (pH). It is also a function of the soil physical environment including texture, structure, pore-size, and water potential. Which of the following would tend to increase the mobility of a nutrient within the soil profile? Select FIVE that apply.

increase in soil water potential from -1250 kPa to -100 kPa change in form of sulfur from elemental So to sulfate (SO42-) change in form of nitrogen from ammonium (NH4+) to nitrate (NO3-) improvement in soil structure from 'puddled' to granular and blocky for phosphorous, a decrease in soil pH from 8.2 to 6.8

The graphs above show the soil carbon dioxide versus days in no-till and tillage systems. In general, how does the use of tillage affect the amount or rate of organic matter decomposition in soils?

increases decomposition by increasing aeration

The most common clay mineral in the soils of Nebraska and surrounding states is

montmorillonite

Soils that contain the clay type _____ will tend to have greater net charge than soils containing similar amounts of _____. Soils found in Nebraska would be expected to contain more _____ minerals while heavily weathered, tropical soils would be expected to contain more ____ minerals

montmorillonite, kaolinite, montmorillonite, kaolinite

The primary net charge on clay minerals is

negative

Soil particles carry an electrical charge that is generally ______. The inorganic soil particles that carry the most charge ______. Soil organic matter is ______ charged.

negative, clay, strongly

The purpose of lime addition to soils is usually to

neutralize H+ in the solution, raise soil pH

During summer, soil ammonium concentration is typically low (near zero). If the soil pH is 6.5 and the water content is at -50 kPa, then the process that most likely explains the low level of ammonium is ...

nitrification

The chemical makeup of a material, especially the amount of ___ present in it, has a major impact on the "digestibility" of any material by soil organisms

nitrogen

The major factor affecting the C:N ratio of any naturally occurring organic material is the percent of nitrogen in that material, because the carbon content of most plants is relatively constant.

nitrogen, carbon

Which of the following pH values indicates that the H+ concentration is greater than the OH- concentration?

pH = 6.2

The cation exchange capacity of a soil depends on all of the following EXCEPT:

particle density of clay

The ability of a nutrient to be mobile (i.e to move) within a soil depends on all of the following except ____

the soil aeration

Which N process is accelerated under high pH conditions?

volatilization

Which of the following N processes is not done by microorganisms?

volatilization