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
Tillages shapes the soil by?
Smooth soil surface
Raise beds
Why till?
Control weeds, Only method before herbicides Bury seeds, rhizomes Some weeds become more problematic Reduce disease inoculum Bury plant residue Disrupt insect life cycles
Two types of tillage?
Primary and Secondary
Leaves the soil surface rough?
Primay Tillage
Moldboard, Chisel, Disk, Sweep
Primary Tillage
Follows primary tillage, prepares seedbed, weed control incorporate herbicides adn uproot weeds
Secondary tillage
Tandem Disk, Rotary Hoe, Harrow, Bedder, Field cultivator
Secondary Tillage
Compare and contrast primary and secondary?
Both used in tillage practices, primary is more economical and secondary is not as economical. Primary leaves the soil rough and secondary is leaves the soil smoother than primary.
Involves plowing and or multiple tillage passes
Conventional
Leaves less than 15 percent residue cover after planting?
Conventional
Advantages of Conventional Tillage?
Excellent Seedbed
Improved aeration
Helps control pests
Levels field for easier harvest
Disadvantages of Conventional Tillage?
More trips across field (time, money for fuel)
Compaction (plow pan may form)
Reduced organic matter
Increases potential for soil erosion
Poor water infiltration and no stopping wind and rain
More than 30 percent of crop residue remains on soil surface?
Conservational
Advantages of conservation tillage?
Reduce erosion by 95%
Better water infiltration increased water use efficiency
Increased amount of land capable of supporting row crops
Increased amount of land managed by one person
Save money on fuel
Disadvantages of conservation tillage
lower yeilds with cool wet springs lower yeidls on poorly drained soils poor distribution of fertilizer increased problems with certain pests increased dependence on herbicides
Zero till, direct seeding or planting
No till
Soil is undisturbed
No Till
Tillage just for seeding
No till
Tillage only for weed control with sweep
Mulch till
Soil is disturbed
Mulch till
Minimum tillage
Strip till
Combining advantages of both conventional and conservation
Strip till
Soil is partially disturbed
Strip till
Planting occurs on the ridge
Ridge till
Formation of ridges 1 year before seeding on ridge
Ridge till
Residue remains in between ridges
Ridge till
Seedbed
Conventional
Pest managment
Conventional
Soil organic matter
Conservational
Compaction
Conventional
Potential Erosion
Conventional
Efficiency Managemtn
Conservation
Slows water runoff, more efficient and easier on equipment
Contour farming
Different than strip till-Alternates grass adn crops, reduce erosion and slows water runoff
Strip Cropping
Remove water in excess, keep level moisture down
Drain tile
Wide strips of native grasslange
Grassed waterways
Variety or hybrid selection consider
Yield, environment, pest resistance, pest management strategy, other desirable traits
An indicator of the ability of a seed to develop into a productive plant
Seed quality
Seed quality factors
Viability Purity Vigor Presence of pathogens, insects, or weed seed Mechanical damage
One way to quantify viable seeds is to calculate the
percent germination
The ability of a seed to germinate under favorable conditions
viability
germinated/total x 100
percent germination
Testing viability
Rolled towel, petri dish
Tetrazolium test
viability of dormant seeds
Potential for rapid emergence of normal seedlings in field conditions
Seed vigor
Tests for seed vigor
Cold test and accelerated aging
Measures the percentage of the desired seed in teh sample
Seed purity
Seed purity must determine
seeds of other crops
weed seeds
inert materials
100%-%other crop-%weed-%inert material =purity
seed purity
Injurious to health or to the environment cant sell or transport
Prohibited
Must be controlled to avoid infestation, only have in small quantities
Restricted
Canada thistle, quackgrass
prohibited
dodder, giant foxtail
restricted
State associations that provide high quality seeds of varieties developed by university breeders
Public seed associations
Most common source of agronomic seeds
Private seed companies
Lowest quality of seed
Farmer saved seed
Farmer saved seed also called
Bin-run or brown bagged
Variation of single row, better use of space, more plants per area
Twin row
Reduce problems with depth, way to push the seeds, developing countries
hill drop
Amount of seeds per area
Seeding rates
Potimum seeding rate is important; too low resluts in
wasted resources
too high results in seeding rates
intraspecific competition
Planting dpth is influenced by
seed size
seed emergence pattern
soil conditions
How efficiently plant uses water
Plant water use efficiency
WUE=
Dry matter produced/water consumed
Total water consumed in teh production of plant biomass
Evapotranspiration
Water lost through transpiration by the plant plus water lost through evaporation from the soil?
Evapotranspiration
Oldest method of irrigation?
Gravity flow or flood irrigation
Flood irrigation is used for soils that are not easily?
Permeable
Advantages of gravity flow irrigation?
Low initial cost
Disadvantages of gravity flow irrigation
High labor costs, land leveling needed, high water losses
Center pivot, lateral move water moves under pressure high investment at beginning
Sprinkler irrigation
Advantages to Sprinkler irrigation
Very uniform application
Lillte land preperation
Low labor costs
Disadvantages to Sprinkler irrigation
High initial cost
Energy needed to pressurize system
High evaportaive losses
Subsurface drip
sUrface drip
Initial cost $1200/AC, Delivers small amount of water, easy to control
Microirrigation
Advantages to Microirrigation?
Very efficient
Low erosion
Disadvantages to microirrgation
High initial cost
Energy need to pressurize system
System may interfere with tillage
Irrigation water should be free of
Particulates and low in salt content
An association between a fungus and the roots of a plant
Mycorrhizae
Improves nutrient and water uptake
Mycorrhizae
Most plants form….associations
Mycorrhizae
Mycorrhizae is a what relatioship
Symbiotic
Non-mineral nutrients
Carbon
Hydrogen
Oxygen
Non-mineral nutrients account for how much dry weight?
96%
Macronutrients
Nitrogen Phosphorus Potassium Sulfur Calcium Magnesium
Account for 3.5% of a plants dry weight
Macronutrients
Micronutrients
Iron Zinc Manganese Copper Boron Chlorine Moybdenum
Sources of Nitrogen, Phosphorus, and Potassium?
Synthetic fertilizer adn organic material (manure)
Is loam a type of soil particle?
No
Correct order for the soil horizon starting from the soil surface:
Horizon A, Horizon B, Horizon C, Horizon R
Physical Condition of the soil is?
Soil Tilth
Soil structure that is the arrangement of soil particles into groups. These groups are called?
Peds
Soil Structure associated with high organic matter?
Granular
Largest constituent of a typical soil?
Minerals
Why is tillage done?
To shape the soil, to manage pests, and to improve soil conditions
PWhich of the following is classified as a primary tillage implement? Tandem disk, Field Cultivator, Chisel Plow, or Lister
Chisel Plow
Advantage of a conventional tillage system?
Helps pest/weed control
Disadvantage of a conservational tillage system?
Increase dependence on herbicides
Name of the form of conservation tillage in which soil is undisturbed and weed control is accomplished with herbicides?
No Till
Characteristic of the conservation practice drain tile?
Removing excess water from soil surface
Type of viability test?
Rolled towel
Define germination?
Process of resuming growth in a seed
Source of agricultural seeds has the lowest quality seeds?
Farmer-saved seed
If a farmer plants too many seeds per acre?
Intraspecific competition
Advantage of the twin-row planting pattern
Better use of available space and increase the amount of plants per area
A small seeded crop should be planted
less deep in the soil
Measure of the total amount of water required to produce one unit of dry matter?
Water Use Efficiency
Oldest method of irrigation?
Gravity flow irrigation
Main disadvantage fo a center-pivot irrigation system?
High initial cost
Irrigation water of good quality sould be low in?
Salt
Irrigation should be done when?
Water potential is preventing plant uptake of water and when the crop is at the critical growth stage
Evapotranspiration differs from transpiration?
ET considers the water lost from the soil and by the plant; transpiration just considers the water lost by the plant.
Association between fungus adn roots?
Mycorrhizae
3 non-mineral nutrients that account for 96% of plant dry weight?
Carbon, Hydrogen, and Oxygen
What are magnesium, nitrogen, and sulfur
Macronutrients
Nutrients required in small concentrations?
Micronutrients
Organic fertilizers can be considered a good source of which nutrients?
Nitrogen and phosphorus
Non-mineral nutrients account for how much of the plants dry weight?
96%
What weeds are only allowed in small quantities in commercial seed?
Restricted noxious weeds
Accelerated aging tests can dtermine the what of seeds?
Vigor
Macronutrients are required in what amounts by the plant?
Large
Soils with what porosity have higher bulk density?
Low porosity
