Chapter 2 Flashcards
(101 cards)
1
Q
What do crops require?
A
Water
Sun
CO2
2
Q
Define soil.
A
(i) The unconsolidated mineral or organic material on the immediate surface of the Earth that serves as a natural medium for the growth of land plants
3
Q
How many soil orders are there?
A
10 different soil orders
4
Q
Why are soils important?
A
- Medium for plant growth
- Part of hydrologic cycle (water supply and purification)
- Part of nutrition cycle (capture, soil and supply nutrients)
- Habitat for soil organisms
- Also an engineering medium
5
Q
What are the components of soil?
A
- Air(25%)
- Water (25%)
- Organic Matter (5%)
- Mineral Particles (45%)
6
Q
Define Porosity
A
Amount of open space between soil particles
7
Q
What are the primary particles of soil?
A
- Gravel (2mm to 75mm)
- Sand (0.05mm to 2mm)
- Silt (0.002mm to 0.05mm)
- Clay(<0.002mm)
8
Q
What is the most important fraction of soil and why?
A
Clay
- vary large surface area
- surfaces are negatively charges (ability to store and release some nutrients)
9
Q
What is soil structure?
A
The arrangement of primary particles into secondary particles (aggregates or peds)
10
Q
What are binding agents of soil?
A
- Roots and fungal hyphae
- Organic material
- Clays
11
Q
What are the benefits of soil texture and structure?
A
- Water holding capacity/drainage
- Susceptibility to erosion
- Fertility (ability to store plant nutrients)
- Pollutant movement and leaching
- Compactability
12
Q
How many trophic levels are there?
A
5 and higher
13
Q
What is in the first trophic level?
A
Photosynthesis
14
Q
What is in the second trophic level?
A
Decomposers
Pathogens
Parasites
Root feeders(nematodes)
15
Q
What is in the third trophic level?
A
Predators (protozoa)
16
Q
What is in the fourth and fifth trophic level?
A
Higher level predators
17
Q
What are beneficial effects of soil organisms?
A
- Decomposition of organic material (nutrient cycling and carbon cycling)
- Plant protection
- Aeration
18
Q
What is soil organic matter?
A
- Biologically derived organic material
- Unaltered materials (forest litter layers)
- Altered decomposed materials (soil humus)
- The dead stuff
19
Q
Define Heterogeneous
A
Material at different stages of decomposition
20
Q
What is the biological importance of SOM?
A
Source of energy for plants and animals
Source of nutrients for plants and animals
21
Q
What is the physical importance of SOM?
A
Stability of soil (stable structure)(Water retention) Soil colour (affects soil temperature)
22
Q
What is the chemical importance of SOM?
A
Nutrient cycling
23
Q
What percentage of organic soils, is organic matter?
A
30%
24
Q
When can organic soils be productive?
A
When properly drained and managed
25
Soil Air is low in ____ and high in ____
Low in oxygen
| High in Carbon dioxide
26
Define aerobic soil
Soil that is high in oxygen
27
Define anaerobic soil
Soil that is low in oxygen
28
Anaerobic and aerobic environments can affect?
Plant growth
Nutrient content
Greenhouse gas emissions
29
What is the importance of soil water?
Serves as a carrier of nutrients
Regulates soil temperature
Soil forming process depends on water
30
How much water goes to agriculture?
58%
31
Define tillage
Preparation of soil often with mechanized equipment
32
What is used for primary tillage?
Ploughs
33
What is used for secondary tillage?
Harrows and cultivators
34
Benefits of Tillage
Soil loosening and aeration
Organic material and nutrient mixing
Mechanical weed destruction
35
What are disadvantages of tillage
```
More exposed soil surface
Increases organic matter decomposition
Decreased organisms
Fuel consumption/greenhouse gas emissions
Soil compaction
```
36
Which type of tillage leaves the most plant residue?
Conservation tillage
37
What types of tillage are used for conservation tillage?
Chisel plough
Strip till
No till
38
What are benefits of conservation tillage?
Reduced soil erosion
Increased organic matter
Reduced evaporation
Reduced energy consumption
39
What are the costs of conservation tillage?
Specialized equipment needed
Colder and wetter soils
Increased herbicide use
40
What are some macronutrients?
C, H, O,N, P, K, Ca, Mg, S
41
How are macro nutrients measured?
PPM parts per million
| 1 PPM = 1 1/4 two litre bottle
42
What are some micro nutrients?
Fe, Mn, Mo, B, Cu, Zn, Cl, Co, Ni
43
How are micro nutrients measured?
PPB parts per billion
| 1 PPB = 1/2 teaspoon
44
What might lead to nutrient deficiencies?
Leached, sandy soil
Intensive cropping
Eroded soils
Soils with low organic matter
45
What pH levels are most soils?
6 - 7.5 pH (neutral)
46
Define Eutrophication
Over fertilization with respect to nitrogen
47
What does nitrogen add to soil?
Atmospheric deposition
Added organic matter
Inorganic fertilizer addition
Biological N fixation
48
In relation to nitrogen what are some losses to the soil?
Very easily lost via leaching
Erosion and run off
Plant uptake
Gaseous losses
49
What are the three biological nitrogen fixation systems?
1. Symbiotic with plant, nodule-forming -
Legumes (Rhizobia bacteria with soybeans)
2. Symbiotic with plants, non-nodule-forming
- Lichens = fungus + cyanobacteria or other bacteria
3. Non-symbiotic – cyanobacteria
50
What is the importance of phosphorus in the soil?
Energy transformations
| Root development
51
What does phosphorus add to the soil? Any losses?
Additions
Fertilizers
Added organic matter
Atmospheric decomposition
Losses
Erosion
Plant uptake and harvest
52
What is the importance of potassium in the soil?
Important in synthesis of proteins, carbohydrates and chlorophyll; helps plants to adapt to environmental stresses
53
What does potassium add to the soil? Any losses?
Additions
Added organic matter
Fertilizer addition
Atmospheric deposition
Losses
Run-off, leaching and erosion
Plant uptake and harvest
54
What are some things in organic fertilizers?
Animal manure
Green manure
Bio solids (industrial waste)
55
What are the benefits to inorganic fertilizers?
Can be applied more precise than with organic fertilizers
| Higher % content
56
When do you apply nitrogen?
Spring
57
When do you apply P, K?
Fall or spring
58
Types of methods to apply fertilizers
Banding prior to, or during, planting
Side - dressing after planting
Foliar application
59
Where is there surplus water?
Areas with high precipitation
Low lying soils or high water tables
Slow draining soils
60
Name the types of soil drainage systems
```
Drainage ditches (follows land contours)
Land smoothing (prevents ponding in depressions)
Tile drainage - buried perforated pipes
```
61
What are the benefits to soil drainage?
Improved workability and aeration
More rapid soil warming
Reduced fungal diseases
Decreased gas emissions
62
What are some problems with soil drainage?
Loss of wildlife habitat
Loss of N
Loss of organic matter
63
Where is there water deficits?
Areas with low precipitation and/or high evaporation
| Excessively well drained soils
64
How do you control loss of water?
```
Control evapotranspiration - controlling weeds and fallow periods
Control evaporation (conservation tillage)
```
65
What is the largest consumptive user of water in agriculture?
Irrigation
66
Name the types of irrigation
Surface irrigation
Sprinkler irrigation
Micro - irrigation (drip or trickle - most efficient)
67
What areas do not have access to good water?
Arid and semi - arid areas
68
What is a pest?
Any organism that has a negative effect on human health or economics
69
Name 3 methods to control pest
```
Chemical control (pesticides)
Cultural control
Physical/mechanical control
Biological control
Genetic control
Natural chemical control
```
70
Benefits of pesticides
Protects crops
Protects health ( malaria)
Convenience/Aesthetics
71
What are the 4 ways pesticides are grouped?
Pests they control
Chemical structure
How/when they work
Mode of action
72
What does postemergent mean?
A weed emerges after seeding
73
What does PCPA stand for?
Pest control products act
74
What does PCPA do?
Pesticide registration and re-evaluation
Human health and safety
Environmental impact
Compliance and enforcement
75
Name 3 commonly used pesticides in Ontario
```
Glyphosate
Atrazine
Diazinon
Chlorothalonil
Neonicotinoids
```
76
What does IPM stand for?
Integrated pest management
77
What is IPM?
Environmentally sensitive approach to pest control
78
What is at the top of the IPM pyramid?
Chemical (pesticide)
79
Soil structure describes the proportion of sand, silt and clay particles present in the soil while soil texture refers to the arrangement of these soil particles into aggregates.
False
80
Top soil is the most productive soil layer because:
It is where most organic matter is found
81
The process by which organisms can take nitrogen from the atmosphere and convert it to soil nitrogen.
Biological Nitrogen Fixation
82
The macronutrient that is difficult to manage because it is very strongly held by most soils is:
Phosphorous
83
In conservation tillage operations at least _____ of the soil surface is covered with plant residues.
30%
84
We generally do NOT find nutrient deficiencies associated with the following soil condition:
Soils with high organic matter contents
85
The Haber-Bosch process is the industrial process used to produce:
Nitrogen fertilizers
86
The first trophic level of a soil food web consists of:
Plants
87
Which of the following statements about soil organic matter is NOT true:
a) Soil organic matter is biologically derived
b) Soil organic matter usually constitutes between 1 and 5% of a mineral soil
c) Soil organic matter is a very homogeneous mixture of materials
d) Soil organic matter constitutes approximately 30% of an organic soil
e) Soil organic matter is very important for soil structural stability
C - Soil organic matter is a very homogeneous mixture of materials
88
Nitrification describes the process whereby:
Ammonium is converted into nitrate (the more plant available form of nitrogen)
89
The following is a broad spectrum herbicide used to kill broad-leaf weeds and grasses:
Glyphosate
90
The following is the commonly used insecticide linked to Honey Bee Colony Collapse Disorder:
Neonicotinoids
91
Systemic pesticides are pesticides that kill as a result of direct contact.
False
92
The environmentally sensitive approach to pest control that uses pesticides judiciously is called:
IPM
93
A soil with greater than 30% organic matter is considered to be an organic soil.
True
94
Moldboard ploughs are generally associated with conservation tillage operations.
False
95
An important benefit of conservation tillage is decreased weeds.
False
96
No-till operations are particularly suitable for cereal crops.
True
97
Soil phosphorous is particularly important for plant root development.
True
98
Broadcasting is better than side-dressing because it involves the localized placement of fertilizers.
False
99
Draining soils can lead to increased fungal diseases in the soil.
False
100
Irrigated agriculture is the largest consumer of freshwater in the world.
True
101
In order to improve the water use efficiency of irrigation the following can be used:
Drip irrigation
