Exam 5 Flashcards
3 sources of phosphorous uptake
Organic
Inorganic
Soil solution
2 uses for phosphorous in plants
- essential in energy transfer
- part of DNA
Phosphorous molecule
Acid: H2PO4-2
Basic: H2PO4-4
Type of movement of soil solution is most phosphorous absorbed by the plant
Most by diffusion
Some by mass flow
Available means
Unavailable means
Available means in a form a plant can use, during the growing season.
Unavailable means it is not in a form a plant can use during the growing season.
2 soil processes that would cause inorganic phosphorous in soil solution to become unavailable.
- Combines with cations
- binds with soil particles
6 functions of potassium (k) in plants
Some enzyme activation Water relations Energy relations Translocation of photosynthate Needed for nitrogen uptake Starch synthesis
4 general sources of k in soil, and which contains most k?
-soil solution (primary source)
-exchangeable-held on soil particles by electrostatic charge (cec)
-nonexchangable- associated with the internal clay structure.
Unavailable-becomes unavailable through normal degradation
K taken up from mass flow vs diffusion
75% diffusion
20% mass flow
K replenish in the soil solution
Exchangeable- primary means to replace soil solution k
Where is the solid exchangeable k located in the soul
.
Where is the solid exchangeable k located in the soil?
.
Where is the non-exchangeable k located?
.
K-fixation
Reduced under acidic conditions?
When expanding clay gets wet k gets trapped between layers
Because under acidic conditions aluminum gets between layers which prevents clay from getting in-between layers.
Luxury consumption of k
When plant takes up more k than needed= wastes. Interferes with ca2+ and mg2+ uptake
Function of ca in plants
Cell division
Elongation
Bud development
2 sources from which ca is slowly available
Calcite
Dolomite
Does available ca revert to a slowly available or unavailable form
No
4 possible fates of ca in ss
-taken up by plant
-held on cec
-microorganisms
Leached
2 functions of mg in plants
Activate enzymes
Critical in photosynthesis
Source of slowly available mg
Dolomite
Mg revert to slowly available or unavailable forms
Yes
6 micronutrients
Boron Copper Iron Manganese Molybdenum Zinc
Micronutrients toxicity?
High quantities in ag/turf soils?
Narrow range from deficient to toxic.
Lots of micronutrients present in fungisides
3 factors that influence micronutrient availability in the soil
- ph
- cec
- om
- parent materials
What are chelates?
Why are they important for micronutrient uptake?
Organic molecules with cation components
- makes metals less reactive
- lets them go into solution
3 reasons nutrient management is needed in agro-forest soils.
-Nutrients are removed faster than normal replacement
????
4 goals of nutrient management
- Cost effective production of quality plants/animals
- Effective use of natural resources
- Maintain soil quality
- Protect Eco system
General nutrient balance situation in poor countries rich countries and regional animal production centers
Poor- expert nutrients- crops low (negative) nutrient levels
Rich- absorb nutrients
Regional- large feed lot operations
Not nutrients….what does nutrient balance sheet need to account for?
1 ability of soil to hold nutrients
2 microbe populations
3 toxin amelioration and processed
Nutrients recognized as pollution
Nitrogen
Phosphorous
What is a nutrient management plan? And examples
A document that specifies a strategy and specific practices for nutrient management
Ie- crop and animal production sequences
Accounting for all for imported nutrient
Max allowed daily loading
Max allowed leaching
4 best mgmt practices for plant production
- Riparian buffer strip-slows run off and absorbs nutrients slows water-flow
- Use of legumes- provide n in soil
- Conservation tillage- reduce erosion
- Maintain vegetation- reduce erosion reduce leaching slow water-flow
3 causes nutrient loss fire/clear-cutting
- Leaching/run-off
- Erosion of A and E horizons where most nutrients reside
- Fire volatilizes nutrients
Diversified farms use should utilize manure?
Manure is a byproduct
Contains nutrients
Om
Why can’t manure sustain fertility?
Animals are sold which removes them from the system
Primary goal Manure collection storage and utilization
-reduce n losses
-collect quickly as possible
-storage-seal it
Utilization- below surface of soil incorporate
How quick is n from manure mineralized after added to soil?
Most released in first year
Main sources of sewage sludge?
Human waste 75 %
industrial waste 25%
What is sewage sludge?
Effluent?
Sewage sludge- solid portion of waste
Effluent- liquid waste
3 main stages of sewage processing
Sewage enters treatment plant as combination of solid and liquid
Water separated from solid
Sludge is treated microbes are added lime and chemicals added
Sludge composition
Mostly carbon, k is low, presents of heavy metal micronutrients
4 potential problems with using sludge in an ag settings
Toxic heavy metals added to food chain Some elements will be toxic to plants Some human pathogens still present Odor Organic poisons
From what are most n fertilizers derived?
- most inorganic salts
- Some are mined (p&k)
- n is mostly derived from atmosphere
What do the numbers of a fertilizer grade indicate exactly?
Amount of nutrients in fertilizer
Fertilizer strategies
Predicted use-amount to reach goal
Annual application-same amount
Replacement-put back utilized
Carry-over- one application over multiple crops
Application operations
Broadcast Banding Fortigation- in irrigation Injection- liquid or gas in soil Pop-up-seed is mixed with fertilizer
Fertilizer concepts
Optimal growth have access to the nutrients needed when it is needed
Apply fertilizer when convenient
Don’t over fertilize
High nutrient demand
Early growth phase and reproduction
Determine the amount of fertilizer needed?
How much is present and how much is needed to reach production goals.
4 means of evaluating fertility
1 problem
Soil test-ability of the soil to provide nutrient. (does not indicate actual uptake)
Plant tissue analysis- if it’s not in plant soil is not supplying (can’t analyze till plant is big enough
Growth analysis- requires extensive historical experience
Symptom deficiency analysis- damage already done.
Diff geological and accelerated erosion
Geo- naturally occurring
Acc-more than geo rate more than 5 tons/acre/year
Acceptable and why?
5 tons natural rate + natural accumulation
Soil-vegetation interdependence related to soil degradation
Poor vegetation creates downward spiral
2 categories of damage erosion
Onsite Loss of soil Loss of best quality Remaining soil has lower whc lower cec lower ph Loss of nutrience Lower biological activity Loss or death of plants Difficulty with equipment use Offsite Smother crop seeds Clog drainage systems Raise stream bed Fills lakes and reservoirs Destroy fish habitat
3 step process of water erosion
Detachment-caused by rain, some by water flow across soil
Transport-caused by water flow downhill fix by terracing contour plowing
Deposition
What causes detachment?
Caused by rain
Some by water flow across soil
What causes transport
3 types of flows
Water flow down hill and splashing
Sheet flow-thin layer evenly spread across soil
Rill-small channels form
Gully larger channels form
Control detachment and transportation
Detachment- Regulation Residues Conservation tillage Transport- Conservation tillage Terraces Contour tillage Stripp cropping
Causes wind erosion to worsen
Wind is strong and soil is weak bare and dry
Wind induced soil particle movement
Suspension- small particles in air
Saltation- sand size particles bounce across ground
Creep- largest soil particles that roll along surface
3 processes of wind erosion
Detachment
Transport
Deposition
Factors wind erosion
Wind velocity Wind turbulence of particles Surface roughness Soil properties Vegetation
Control wind erosion
Wind breaks
Maintain soil moisture
Conservation tillage
Maintain vegetation cover
