Term
Essential nutrients are chemicals that all
plants require to complete their______ ______. |
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Definition
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Term
___________ __________refers to the ability of a soil to
supply nutrients and provide favorable
conditions for plant growth |
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Definition
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Term
| The dry components of plants include the following nutrients: |
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Definition
N, nitrogen
K, potassium
P, phosphorus
Ca, calcium
Mg, magnesium
S, sulfur |
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Term
| The dry components of plants include the following essential elements: |
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Definition
C, carbon
H, hydrogen
O, oxygen |
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Term
| What are the micronutrients? |
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Definition
Iron (Fe)
• Manganese (Mg)
• Molybdenum (Mo)
• Chlorine (Cl)
• Copper (Cu)
• Boron (B)
• Zinc (Zn)
• Nickel (Ni) |
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Term
30‐50% of total U.S. food production
is due to the use of ______ _______. |
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Definition
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Term
| N losses from soil can be controlled,but not _________. |
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Definition
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Term
N is a significant and widespread
environmental contaminant of ____ and ____. |
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Definition
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Term
| 4 Sources of Nitrogen pollution. |
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Definition
- auto exhaust
-agricultural use (fuel and fertilizer)
-animal waste
-human waste |
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Term
| What is the nutrient most often limiting to plant growth and productivity in terrestrial ecosystems? |
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Definition
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Term
| What part of the plant is affected first when there is a nitrogen deficiency? |
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Definition
General yellowing (chlorosis) of oldest
leaves, followed by death (necrosis). |
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Term
| Nitrogen is _______ within plant. This is why oldest leaves are affected first. |
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Definition
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Term
| How does the loss of Nitrogen from soils pollute the atmosphere? |
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Definition
| Nitrous oxide, N2O, is a greenhouse gas and contributes to heating the atmosphere. |
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Term
| How can loss of Nitrogen from soils pollute groundwater? |
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Definition
| NO3- is leached into groundwater and is harmful to humans and animals. |
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Term
| How can Nitrogen loss from soils pollute surface water? |
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Definition
| Eutrophication- Nitrogen stimulates algal growth which can cause hypoxia (dead zones), killing fish and other aquatic life. |
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Term
| Plants take up N from the soil solution in either of two inorganic ionic forms: |
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Definition
– Ammonium (NH4+)
– Nitrate (NO3‐ )
• Most plants can use both forms |
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Term
| What form of N is most prevalent in well drained soils? |
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Definition
| NO3- (oxidized,valence +5) |
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Term
| What form of Nitrogen is dominant in waterlogged soils? |
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Definition
| NH4+ (reduced, valence -3) |
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Term
| More than 95% of N in surface soils is organic N, how is this relevant to plants? |
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Definition
| It is found in Humus, plant & animal residues and is not directly bioavailable and must be mineralized |
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Term
| What are the 5 forms of Nitrogen found in solution? |
|
Definition
– Ammonium, NH4+ (plant nutrient)
– Nitrate, NO3‐ (plant nutrient)
– Nitrite, NO2‐
– Urea (NH4)2CO
– Amino acids & other soluble organics |
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Term
| What are the two bioavailable forms of soil N? |
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Definition
| ammonium (NH4+) and nitrate (NO3‐) |
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Term
| What are the inputs of the N cycle? |
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Definition
| – N2 Fixation, Organic Matter deposition, Rainfall, Fertilization |
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Term
| What are the transformations of Nitrogen in the N cycle? |
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Definition
| – Immobilization, Mineralization, Nitrification |
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Term
| What are the losses found in the Nitrogen cycle? |
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Definition
– Denitrification, NO3
‐ leaching, NH3 volatilization |
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Term
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Definition
| The process wherein N2 is converted into NH4+ or NO3 |
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Term
| What are possible causes of N2 fixation? |
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Definition
| • microorganisms, lightning, industry |
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Term
| Biological N2 fixation is: |
|
Definition
| A symbiotic association between bacteria or actinomycetes and plants |
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Term
| What are some examples of biological N2 fixation? |
|
Definition
• Rhizobium leguminosarum trifoli and white clover
• Bradyrhizobium japonicum and soybean
• Actinomycete Frankia and alders, other shrubs and trees
• Between 40 and 275 kg N/ha/year can be fixed by Sinorhizobium meliloti
living symbiotically with alfalfa |
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Term
| What organisms perform non-symbiotic N2 fixing? |
|
Definition
-cyanobacteria
-heterotrophic bacteria
(they fix less than symbiotic N fixers) |
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Term
| What is the Haber Bosch process? (equation) |
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Definition
|
|
Term
| Haber-Bosch accounts for what percentage of all global N2 fixation? |
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Definition
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Term
| Organic Nitrogen stability depends on 3 things. What are they? |
|
Definition
1. Complexity of N containing compound
2. C:N ratio
3. Soil conditions |
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Term
| Immobilization is the conversion of ________________ and has a _______ C:N ratio. |
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Definition
| inorganic to organic, high |
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Term
| Mineralization is the conversion of ________________ and has a _______C:N ratio. |
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Definition
| organic to inorganic, low |
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Term
| A 2‐step biological oxidation of NH4+ to NO3‐: |
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Definition
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|
Term
2NH4+ + 4O2 -----> 2NO3‐ + 2H2O + 4H+
What is represented by this equation? |
|
Definition
|
|
Term
| Why is nitrification important? |
|
Definition
• consumes NH4+ produced by N fixation
• produces NO3‐
• produces acidity (H+) |
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Term
| In warm, moist soils NH4+ is converted to NO3‐within _____________. |
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Definition
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Term
_____________ is the biological reduction of NO3‐ (oxidized N) to more
reduced forms |
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Definition
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Term
Approximately ___ of all fertilizer N is lost from soils
by denitrification. |
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Definition
|
|
Term
| Denitrification can occur rapidly under what favorable conditions? |
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Definition
• low O2 levels (flooded soils)
• supply of readily available carbon
• presence of nitrate or nitrite
• favorable temperatures |
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Term
| Denitrification is the major source of what gas to the atmosphere? |
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Definition
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Term
| Nitrate is very susceptible to leaching, because: |
|
Definition
it is an
anion and is not adsorbed to soil colloids |
|
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Term
| Nitrate leaching degrades _______ ______. |
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Definition
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|
Term
NH3/NH4+ balance is determined by pH.
– NH3 prevails under _______ conditions (it is a volatile gas)
– NH4+ prevails in _____ conditions |
|
Definition
|
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Term
| In most natural ecosystems, Most N is: |
|
Definition
| tied up in plant biomass and soil organic matter |
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Term
| Most crops cannot host symbiotic N fixers, so they need N from: |
|
Definition
• Animal manures
• Chemical fertilizers
• Soil organic N mineralization |
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Term
| How can you properly manage efficient use of N fertilizer? |
|
Definition
– Incorporate NH4+ fertilizers
– Do not over‐irrigate
– Do not apply a whole season’s N at once (split applications) |
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Term
| Sulfur is critical for _____ _______. |
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Definition
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Term
| WHat is the most abundant form of Sulfur in temperate region soils? |
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Definition
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Term
| In anaerobic soils, sulfur is present in ________ ________. |
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Definition
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Term
| In anaerobic soils, sulfur is present in _____ ______. |
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Definition
|
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Term
| The main form of sulfur in desert soils is _______. |
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Definition
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Term
| What is the main inorganic form of S in aerobic soils? |
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Definition
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Term
| ________ is the form of sulfur taken up by plants. |
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Definition
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Term
| In aerated soil, reduced S is ________ ______. |
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Definition
|
|
Term
| How is sulfur dioxide SO2 produced? |
|
Definition
| coal combustion, metal ore smelting |
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|
Term
S Deficiencies are most
likely in: |
|
Definition
– sandy soils
– low organic matter soils
– highly leached soils |
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|
Term
| S deficiencies are not likely in: |
|
Definition
– irrigated areas (most irrigation water contains enough sulfate salts to satisfy plant S needs)
– desert soils |
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