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TAMU SCSC 301 Final Exam 2024/2025 Latest Exam Accurate
Fall/Spring Term Score A (Answered)
Acid Dissolution The transformation of a primary mineral to a secondary mineral could occur through which weathering process? Increases macroporosity, allowing a better mix of air and water Fine-textured soils require aggregation to become more suitable for plant growth because it ________. Soil Texture Which soil property is not affected by land management practices (i.e., it is an inherent property of the soil)? O, A, B A soil contains O, A, B, and C master horizons. Which of the horizons in this soil are included in the soil solum? Climate Which soil forming factor is active? Hydrolysis Which process is an example of chemical weathering? sandy clay Which soil structure has the highest clay content?
weak coarse granular What phrase best describes soil structure? Al Which element is not essential for plants, but is common in rocks and soils? Particle volume only Particle density is the oven dry mass of soil divided by_____. Oxygen A soil that supports plant life must provide___ to the roots of the plants. 2.6 g/cm What is the most probable (likely) particle density for a mineral soil? 1.2 to 1. The range in bulk density found in typical mineral soils is _________ g/cm3. all of the answers represent factors affecting microorganism growth Which of the following affects microorganism growth?
- soil pH and exchangeable Ca
- type and abundance of organic compounds in soil
- all of the answers represent factors affecting microorganism growth
- soil moisture and temperature
- oxygen concentration in the soil Mycorrhizae This organism is able to form a symbiotic relationship with plants that improves the plant's ability to acquire water and nutrients and may also protect against pest, while the organism receives carbohydrates directly from the plant
The soil bulk density is 1.2 g/cm3 and the particle density is 2.6 g/cm3. What is the percentage of pore space (i.e., porosity) of the soil________% Biota; Parent Material Soil is a dynamic natural body having properties due to the combined effects of climate and _______as modified by topography acting on ________over time. 2,000,000 lbs The mass of 1 acre of soil with a 6 inch depth and a soil bulk density = 1.5 g/cm3 is approximately Organic matter and clay Aggregation of soil particles is related to the content of_________. organic matter decomposition Which of the following is a major role of soil microorganisms? mycorrhizae and yeast Which of the following are types of fungi? Redox Which type of chemical weathering involves the change in oxidation state of an element caused by the transfer of electrons? Loess Deposits of sediments by wind are known as_____. Disperse clay colloids Which of the following is something soil organisms DO NOT typically do in the soil?
Soil texture Soil compaction has no effect on___. Glacial The parent material transported by ice is___. Lower percentage of basic cations (i.e., Ca, Na, Mg, K) As rocks weather into soil, some elements are lost and are removed from the system. Thus, the chemical composition of soil (developed as residuum) will have a______________than its parent rock
A soil sample has a wet mass of 180 g, dry mass of 130 g, a total volume of 100 cm3, and particle volume of 80 cm3. What is the soil's bulk density in g/cm3? Sodium (Na) This cation is most likely to promote dispersion and not flocculation or dispersion. Large surface area Small soil particles with high reactivity have a___________. Fe and Al oxides The ultimate products of weathering are secondary minerals that are resistant to further weathering. These include minerals, such as hematite and gibbsite, which are described as (i.e., made up of) ________. Texture The percentage of sand, silt, and clay particles in soil define the ____________of a soil
0 kPa A soil that is saturated and starting to flood will have a soil water potential around ________ Water will move into the clay as soon as the wetting front reaches it Water moves from the A horizon (loamy sand) down into the B horizon (clay), which is true? Umbric Thick (i.e., >20 cm), dark, mineral surface horizons having >1% organic matter and low base saturation would describe a(n) _________epipedon. Humus or stabilized organic matter Which term includes unidentifiable (by organism or chemical composition) organic materials in soil that are not living? VIIs Which land use capability unit has a severe limitation based on soil depth? Aerobic, temperature warm (>18°C/65°F), and moist (not saturated) Decomposition of residues occurs most rapidly when soil is _______ Bss A subsoil horizon in which slickensides are present is a ______ horizon Weswood silt loam, 0 to 3% slope Which soil mapping unit is the most homogenous (i.e., most uniform and least variable in the area where it is mapped) New Mexico (warm arid to semi-arid climate)
Which environment would likely have the LEAST soil organic matter? The amount of water in a soil after excess water has drained completely from it Which answer describes field capacity best? udic The Songag series is classified as medial, ferrihydritic, thermic Typic Hapludands. What is the soil moisture regime? (Hint, it is in the subgroup) A-E-Bt-C Which of the following represents a possible sequence of master horizons from the surface downward? Polyphenols/tannins Which compound is considered the most difficult to degrade by soil organisms? Hairy Vetch (11:1) Which cover crop will contribute the most N to the soil if it was left to decompose in the field after it was grown (i.e., via green manuring)? Immobilization Which process is likely to result in a nitrogen depression period after residues are added to the soil? All water pores are filled and gravitational flow is dominant force moving water When water moves under saturated flow, which is true Alfisol A subsoil horizon containing an accumulation of clay with high bases could be indicative of which soil order?
Soil C: A-C Soil D: A-Bo1-Bo2-C Tropical rainforest with hyperthermic soil temperatures (e.g., Brazil, Puerto Rico) A soil with ochric and oxic horizons would most likely be found in a(an) ___ the soil has many preferential flow pathways Water can sometimes move rapidly through the soil when_____ Entisol A soil that does not have an E or B horizon is most likely going to classify as ___ Stabilizing aggregates Organic matter affects soil structure by _______ Becomes more negative (i.e., decreases) As soil dries the matric potential_______. Adhesion When water is attracted to soil particles, this attraction is called____. It is faster than anaerobic and results in a more complete decomposition Which is true regarding aerobic organic matter decomposition? kandic and oxic Soils that form in warm temperate to hot tropical climates on stable landforms and allow the soil plenty of time to develop (i.e., weather) without any influence from volcanos are likely to contain these horizons:
In any direction Water movement due to matric forces can occur___________ Wilting Point; Field Capacity Plant available water is held between the _________ and ___________ Addition of organic residues with C/N ratio of 100: Which of the following is likely to result in immobilization of N? Humus Formation of ______ occurs due to the incomplete oxidation of organic residues by soil organisms. Matric forces acting on it Water movement upwards and horizontally in a profile is due primarily to _________ Andisol The Songag series developed on cinder cones and are derived from pyroclastic materials. They are classified as medial, ferrihydritic, thermic Typic Hapludands. What soil order would they fall into? K+ ions The interlayer of mica is dominated by ________ all of the answers contribute to soil acidification over time Which process contributes to soil acidification over time?
- continuous crop production
- leaching of basic cations
- all of the answers contribute to soil acidification over time
- acid rain
- nitrification
Which of the following is a component of the water balance equation that represents evaporative and transpiration losses of water from a soil? Gully erosion Which type of water erosion can NOT be repaired by standard soil moving equipment (e.g., plow)? Mulching the soil surface Which practice reduces evaporation from the soil surface? soil air < soil solids < soil water The soil components (i.e., soil water, soil solids, soil air) arranged in order of increasing heat capacity (lowest heat capacity first) are ______________ decrease As a generalization, the weathering of soils causes the pH to _______ over time leaving crop residue on the soil surface ET losses from soils can be reduced most by: compaction Which property of the soil has the most influence in soil warming in the Spring, assuming the soil is bare? (Hint: heat must be conducted from atmosphere down) Adding furrow dikes and contour rows Which management encourages infiltration? strip cropping The erosion control practice of ______ involves planting crops in narrow strips and alternating them across a landscape, particularly perpendicular to erosive forces.
A wet soil will take longer to warm up in the spring than a dry one Which is true about the specific heat of a soil? Displacing exchangeable Al and H into the soil solution allowing them to be neutralized When applying lime, calcium and magnesium assist the pH increase by ______ Having a maximum temperature later in the day In the summer, daily fluctuations in temperature at 30 cm depth differ from those at the soil surface by: O Under normal aerated conditions, soil air compared to the atmospheric air almost always contains a lower percentage of ______ smectite Which of the following is a colloid that is found in soils? crop management including vegetative cover In the equation of soil losses due to water erosion, A=RKLSCP, the C variable represents the: All of the above Oxygen concentration in the soil is dependent on_________
- Air-filled pore volume
- Macroporosity
- Microbial Activity
- Water content
- All of the above Fe/Al oxide < chlorite < smectite < humus
Al3+ 1 agricultural CaCO The most economical means of increasing soil pH from 4.5 to 7.0 in a non-calcareous soil is by the addition of _____ measured pH of the soil Active acidity represents ______________ imperfections in the crystal lattice caused by substitution of one cation for another of similar size, which is called isomorphic sustitutions Permanent charge on colloids occurs due to ________ none of the answers are correct The strong buffering action in soils ,when the soil pH is between 5 and 7, is most likely due to
- The presence of exchangeable Al3+
- none of the answers are correct
- High levels of oxide-containing minerals
- high levels of soil organic matter
- The presence of carbonates all answers are correct Why is the liming effect rarely permanent?
- acidification processes are not halted
- weathering of minerals likely results in addition of Al, which is acidic
- all answers are correct
- lime rates do not completely neutralize all residual and exchangeable acidity P If a farmer was installed grassed waterways and strip cropping, which factor of the Universal Soil Loss equation would he be affecting?
Climate and biota Soil is a dynamic natural body having properties due to the combined effects of ____________ as modified by topography acting on parent material over time. 25 A typical moist surface soil ideally contains _________% water on a volume basis. Carbon dioxide A soil that supports plant life must provide which of the following, EXCEPT Feldspars, Hornblende, and Mica Primary minerals that may weather to form secondary clay minerals in soils include: Quartz A primary silicate mineral that is resistant to weathering is: Hornblende and feldspar Which of the following weathers to form silicate clay minerals in soils Gypsum Which of the following mineral is the most soluble? This high solubility causes it to easily weather and be lost from soil profiles. Profile A two dimensional vertical cross sectional view of a soil is referred to as a soil __________ A, B Which horizons in a soil containing A, B, C, and R horizons are included in its soil solumn?
Particles will settle in order of decreasing size and density (i.e., large dense particles settle first) A major assumption made in applying Stoke's Law to sedimentation of soil particles in a cylinder is: Sandy loam, clay loam, clay The most probable sequence of soil textures surface to subsoil (e.g., A, B1, B2) is More porous Surface soils are ____ than subsoils Hydrolysis The transformation of a primary mineral to a secondary mineral could occur through which process? Soil texture Which physical soil property is an inherent property of the soil that cannot be changed in our lifetime? Organic matter and clay Aggregation of soil particles is related to the content of .Granular, subangular blocky, massive The most probable sequence of aggregate types from the surface downward in a soil is: Medium The structure of a soil horizon is reported as "strong, medium, crumb". Which is the structural size? Particle + pore volume
Bulk density is the oven dry mass of soil divided by ________________ 1.2 to 1. The range in bulk density for typical mineral soils that are suitable for plant growth is ________g/cm 32 The porosity of the soil with a bulk density of 1.7 g/cm3 and a particle density of 2.5 g/cm is_____%
Which value is most likely represents the particle density of a soil? Increases macroporosity Aggregation helps fine-textured soils become more suitable for plant growth because it
Consistence The behavior of a soil in response to manipulation at a specified moisture content is: Soil texture Soil compaction has no effect on _________ Macroporosity From a plant's perspective, the most important role of soil structure in fine-textured soils is to increase____. Hue The dominant wavelength of light (i.e., color) reflected by a soil is called _______.
