Exam 3 Flashcards
A dynamic natural body composed of minerals and organic material and living organisms in which plants grow is what?
Soil
Composition of a soil with 45 degrees is what?
minerals
Composition of a soil with 5 degrees is what?
organic matter
Composition of a soil with 25 degrees is what?
air
Composition of a soil with 25 degrees is what?
water
Soil develps as a result of the combined effect of? Which acts on? And is influenced by ?
climate and organisms
soil
topography over time
What is a layer of soil parallel to the surface differing in characteristics from the soil above and below?
Soil Horizon
Which horizon is the mineral horizon enriched with organic matter?
A
Which horizon is the less-weathered horizon where materials such as clay accumulate?
B
Which horizon is unconsolidated parent material; least weathered horizon?
C
Which horizon is consolidated rock?
R
Which is horizon is the most important for plant development?
A
What is the organic horizon?
Grass
What horizon are most roots found in?
A
Soil provides plants with?
A place to anchor roots
Water
Mineral nutrients
Soil tilth-the physical condition of the soil as it relates to?
tillage
planting
germination
emergence
A soil with good tilth will have adequate? Which holds? and will have an adegquate supply of?
pore space
water and air
nutrients
What physical condition is texture, structure, soil organic matter, density, and porosity?
Tilth
Soil tilth is the function of soil?
Structure
Texture
Fertility
Organic Matter
Maintaining soil tilth requires careful?
It is improved by reducing?
Timing of farming operations
Tillage
Soil properties that influence soil tilth and crop growth?
Texture Structure Soil Organic Matter Density Porosity
The relative proportion of various sizes of soil particles is?
Soil texture
What soil particle size is < .002 mm
Clay
What soil particle size is 0.002-0.05 mm
Silt
What soil particle size is 0.05-2.0 mm
Sand
Soil Textures are
Clay
Silt
Sand
Loam
Is loam considered a soil particle?
NO
What is the arrangement of soil particles in to groups called?
Soil structure
Soil structure groups are called?
Peds or aggregates
Soil structure may be an indicator of soil…
organic matter content or compaction
Resembles cookie crumbs and is usually less than .5 cm in diameter. Commonly found in surface horizons where roots have been growing
Granular
What horizon are most roots located on?
A horizon
What soil structure is thin, flat plates of soil that lie horizontally and are usually found in compacted soil?
Platy
Platy have low accumilation of?
water
What soil structure is irrgular blocks that are usually 1.5-5.0 cm in diameter and are common in subsoils or C horizon
Blocky
What soil structure has vertical columns of soil that might be a number of cm long and are usually found in lower horizons and are very long adn deep within the soril adn are B or C horizons?
Prismatic
What soil strucuter has vertical columns of soil that have a salt “cap” at the top and are found in soils of arid climates with dense, low water movement?
Columnar
Which soil structure has high organic matter?
Granular
The residues of plants, animals, and microorganisms broken down over time is?
Soil organic matter
Most soils contain how much organic matter?
1 to 6%
Decompostition of living organisms is how much carbon?
45-50%
Release of NPK is?
Nutritional
Important for living organism is?
Biological
Increase water and air capactiy and also improves the porosity is?
Physical
What is the porosity?
How many pores are in the soil
Functions of soil organic matter?
Contributes to soil tilth
Increases water holding capacity
Releases mineral nutrients for plants
What is the mass of soil per unit volume or Dry soil mass/soil volume?
Bulk Density
High bulk density makes what difficult?
Root growth and tillage
Higher organic matter=
lower bulk density
Soils with low porosity have?
Higher bulk density
A portion fo a volume of soil that is not occupied by soil particles and are spaces filled with water or air is?
Pore space or Porosity
Large pores are called?
Macropores
Small pores are called?
Micropores
Macropores have roots that?
Penetrate easier here and there is a higher amount of air
Micropores is where what is found?
Water
Pore space is occupied by?
Either air or water
Total pore space is usually what and water content what?
Lower and higher at greater depths
Which horizon has a higher porosity?
A
The process of exchanging gases between the soil and the atmosphere is what?
Soil aeration
What is organisms living in the soil (including plants) use oxygen to produce carbon dioxide in respiration?
Soil aeration
Unbalanced aeration can accumulate what?
Toxins
The amount of water a soil is able to hold is?
Soil water content
Soil water content is determined by?
The number of pore spaces available adn the size of the pores that hold water
Soil water content can be measured as?
Weight or volume
Water content does not equal water?
Availability
The more negative the water potential, the ….. the plant has to work
harder
Do soil characterisitcs affect how land is used?
Yes
Only about what percent of the earth’s surface is arable land?
11
Most of the world’s utlized arable land is in?
US, Europe, and Asia
Soil characteristics and land use can be predicted by knowing?
Soil orders
How many soil orders are there?
12
Agriculturally important soil orders are?
Mollisol, Alfisol, and Ultisol
What soil order is dark coloration formed under grasslands and are very fertile and high in nitrogen?
Mollisol
What soil order looks like clay, translocation of clay, and naturally fertil so less fertilization?
Alfisol
What soil order has red coloration, humid and warm regions, adn need right management to be reproductive?
Ultisol
Reasons for tilling?
Improve soil condition, shape soil, and manage pests
Agricultural preperation fo the soil is?
Tillage
Prepare seedbeds, controls weeds: eliminates competition, adn improves physical conditions of the soil is?
Tillage
Tillage improves?
Seed/soil contact
Tillage influences?
Soil structure
Water holding capacity
Drainage
Aeration