AGRY 105 Exam 3 (Lectures 25-37)
Potassium sulfate
0-0-50
Potassium choloride
0-0-60
Triple superphosphate (TSP)
0-46-0
Final soil sample
1 pint, mixture of all the subsamples to create sample
Factors that add nutrients to the soil (5)
1. Atmosphere 2. Fertilizers 3. Biological fixation 4. Microbial decomposition of organic matter 5. Weathering of parent materials
Factors that add nitrogen to the nitrogen pool (4)
1. Atmosphere (lightning/air) 2. Fertilizers/manure 3. Microbial decomposition of organic matter (free living bacteria) 4. Biological nitrogen fixation (symbiotic bacteria)
Common liming materials
1. Calcitic limestone (calcium carbonate) 2. Dolomitic limestone (Ca & Mg)
Factors influencing crop injury from seed-placed fertilizers
1. Crop sensitivity 2. Distance from seed 3. Soil factors (pH) 4. Rainfall after planting 5. Fertilizer factors
Factors that remove phosphorus from the phosphorus pool (4)
1. Crop/plant uptake 2. Crop removal 3. Soil erosion/runoff 4. Leaching
Factors that remove potassium from the potassium pool (4)
1. Crop/plant uptake 2. Crop removal 3. Soil erosion/runoff 4. Leaching
Factors that remove nitrogen from the nitrogen pool (6)
1. Crop/plant uptake 2. Crop removal 3. Soil erosion/runoff 4. Leaching 5. Volatilization 6. Denitrification
Factors that add phosphorus to the phosphorus pool (3)
1. Fertilizers/manures 2. Weathering of parent materials 3. Microbial decomposition of organic material
Factors that add potassium to the potassium pool (3)
1. Fertilizers/manures 2. Weathering of parent materials 3. Microbial decomposition of organic matter
Ways to reduce manure runoff
1. Incorporation 2. Application to fields with growing crops or substantial residue 3. Avoid steep slopes or land close to surface waters 4. Avoid spreading in winter, especially on frozen soils
Factors that remove nutrients from the soil (5)
1. Leaching 2. Nutrient Fixation 3. Erosion/runoff 4. Volatilization 5. Plant uptake
Functions of Nitrogen (N) in plants
1. N is a major part of the chlorophyll molecule (essential for photosynthesis) 2. N combines with C, H, O, and S to create amino acids, the building block of proteins 3. Amino acids are used in forming protoplasm, the site for cell division in thus for plant growth and development 4. Since all plant enzymes are made of proteins, N is needed for all of the enzymatic reactions in a plant
Function of Phosphorus (P) in plants
1. Plays major role in energy storage and transfer as ADP and ATP 2. Is part of RNA and DNA structure (major components of genetic information) 3. Seeds have high concentration of P in a mature plant and is required in large quantities in young cells where metabolism is high and division is rapid
Function of potassium (K) in plants
1. Promotes metabolism 2. Controls opening and closing of leaf stomates 3. Maintains balance of electrical charges at site of ATP production 4. Improves disease resistance, improve size of grains and seeds, and improves quality of fruits and vegetables 5. Seeks have a high concentration of K in a mature plant
Importance of soil pH
1. Root growth 2. Nutrient availability 3. Microorganism activity 4. Symbiotic nitrogen fixation 5. Effectiveness of some pesticides and heavy metals 6. Growth and development (crop yield and quality)
Soil Sampling (timing)
1. Sample at the same time of year 2. Most soils should be sampled every 3-4 years (sandy soils every 1-2) 3. Time of year - in fall after harvest or spring before planting
Factors important for tissue sampling
1. Sampling location (field) 2. Sampling location (plant) 3. Growth stage 4. Number of samples 5. Time of day 6. Sample handling
Field characteristics influencing nutrients
1. Soils - texture, organic matter, etc. 2. Past crop management practices - crops grown, former fence lines, etc. 3. Previous nutrient application method 4. Nutrient stratification 5. Nutrient availability changes over time (e.g., K levels from late summer to early fall) 6. Weather 7. pH
Factors influencing nitrification (4)
1. Temperature (as temp increases, so does nitrification) 2. Soil moisture (increased moisture=increased nitrification 3. Soil pH (as pH increases, so does nitrification) 4. Nitrification inhibitors (chemical compounds that slow nitrification)
Products to improve fertilizer efficiency
1. Urease inhibitors 2. Nitrification inhibitors 3. Polymers 4. Chelated 5. Slow release fertilizers
Nutrient status assessment methods (5)
1. Visual appearance 2. Remote sensing 3. Crop yields 4. Soil testing 5. Plant tissue sampling
Contributors to the soil solution (6)
1. Weathering of soil rocks and minerals 2. Decomposition of organic matter 3. Biological fixation 4. Atmosphere 5. Fertilizer/other additions 6. Number of exchange sites and organic matter
Ammonium polyphosphate
10-34-0
Monoammonium Phosphate (MAP)
11-52-0
Potassium nitrate
13-0-44
Diammonium phosphate (DAP)
18-46-0
Ammonium sulfate (S)
21-0-0 (NH4)2SO4 Solid, forms ammonium in soil Made by reacting ammonia with sulfuric acid Well suited as top-dress application Not subject to volatilization
UAN Solution (L)
28-0-0 Urea ammonium nitrate solution Mixture of urea and ammonium nitrate in water About 3/4 ammonium, 1/4 nitrate Clear, corrosive liquid Can mix with herbicides
Ammonium nitrate (S)
34-0-0 NH4NO3 Solid, forms both ammonium and nitrate in soil Used for explosives as well as fertilizer (highly regulated)
Urea (S)
46-0-0 (NH2)2CO Ammonium forms in soil Solid, made from anhydrous ammonia High use around world Occurs naturally (animal urine)
Anhydrous ammonia (G)
82-0-0 NH3 Ammonium forms in soil Gas at room temp, compressed to store and handle Dangerous to handle
Analysis
A fertilizer's formulation of the three macronutrients (nitrogen, phosphorus, and potassium
Surface application
A method by which a fertilizer is applied directly on the surface of a field (soil and/or plants)
Factors that increase soil pH (more basic)
Addition of liming materials Accumulation of basic cations Irrigation of high pH water
Adsorption
Adhesion of atoms, ions, or molecules from a gas, liquid, or dissolved solid to a surface
Liquid manure storage
Advantages: Can handle with conventional pumping and irrigation equipment Treatment reduces odors Disadvantages: Large land area Higher loss of nutrients during storage
Solid manure storage
Advantages: Relatively low odor Relatively high nutrient retention Disadvantages: More labor than liquid or slurry Runoff from outside lots
Slurry manure storage
Advantages: Higher nutrient retention than liquid system Less labor than solid Disadvantages: Odor Danger of toxic gas buildup
Aspects of manure fertilizers
Amount of nutrients more variable and less reliable Both organic and inorganic forms of nutrients in manure Organic nutrients must be mineralized Not all nutrients in manure available to plants the same year as application Cheap source of fertilizer
Factors that decrease soil pH (more acidic)
Application of acid-forming fertilizers (N & S) Leaching of basic ions by water (Ca, Mg, K) Removal of basic cations by crops (Ca, Mg, K)
Soil zone sampling
Based on field characteristics: 1. Soils present 2. Size 3. Topography 4. Past crop yields 5. Cropping history
Micronutrients (needed in very small amounts) (8)
Boron, Iron, Molybdenum, Manganese, Zinc, Copper, Chlorine, Nickle
Secondary nutrients (needed in larger amounts, but less than macros) (3)
Calcium, Magnesium, Sulfur
Non-mineral nutrients (3)
Carbon, Hydrogen, Oxygen
Immobilization
Conversion of ammonium (NH4+) and Nitrate (NO3-) to organic nitrogen (nitrogen becomes less available to plants); Taken up by soil organisms - Microbes always win because of their numbers
Nitrification
Conversion of ammonium (NH4+) to nitrate (NO3-); nitrogen becomes more susceptible to leaching
Mineralization
Conversion of organic matter (nitrogen) to ammonium (NH4+); Nitrogen becomes more available to plants
Mass flow
Dissolved nutrients move to the root in soil water that is flowing towards the roots as the plant takes up water for transpiration
Sidedress
Fertilizer is applied along the side of a crop
Topdress
Fertilizer is applied on the surface of a field
2x2 fertilizer application
Fertilizer is placed below and to the side of the seed (2", 2")
Pop-up fertilizer application
Fertilizer is placed directly under the seed
Organic fertilizers
Fertilizers derived from living materials: animal manure, vegetable matter (compost); slow release fertilizers
Inorganic fertilizers
Fertilizers that are synthesized or mined from nonliving materials; quick release fertilizers
Injected application
Forcefully introducing a fertilizer into the soil
Common soil cations (positive charge)
H+ (hydrogen), K+ (potassium), Na + (sodium), Mg +2 (magnesium), Ca +2 (calcium), Fe +2 (ferrous), Fe +3 (ferric)
Ideal and common pH for agricultural soils
Ideal: 6.5 to 7 Common: 5-8
Nitrogen deficiency symptoms
In corn, V-shaped yellowing In soybeans, light green color
Phosphorus deficiency symptoms
In corn, blueish-green with reddening of margins In soybeans, dark to blueish-green leaves
Sulfur deficiency symptoms
In corn, light green with interveinal striping In soybeans, pale yellow-green new leaves
Manganese deficiency symptoms
In corn, slight yellowish stripe on upper leaves In soybeans, interveinal area of leaves becomes yellow or light green to white
Iron deficiency symptoms
In corn, stunting, interveinal area of upper leaves yellow or pale green to nearly white In soybeans, stunting, interveinal yellowing of young leaves
Zinc deficiency symptoms
In corn, white, interveinal stripes (midribs stay green) In soybeans, stunting of stems and interveinal yellowing of younger leaves
Magnesium deficiency symptoms
In corn, yellow to white interveinal striping or beaded streaks of dead spots In soybeans, general symptoms of N deficiency
Potassium deficiency symptoms
In corn, yellowing of leaf margins In soybeans, yellowing of leaf margins
Soil sampling (spatial)
In tilled field, 8" In no till, 0-4" and 0-8" 20-30 core samples, random, zigzag, or diagonal patterns across 25 acres or less
Soil pH
Indicates acidity of soil solution; ACTIVE acidity
Buffer pH
Indicates acidity on the soil particles; RESERVE acidity
Fertigation
Injection of fertilizers or other water soluble products into an irrigation system
Soil pH
Level of acidity or alkalinity; acid soils have more hydrogen ions (H+), basic soils have more hydroxyl ions (OH-)
Organic fertilizer application rate
Limited by the nutrient that causes the greatest problems to plant or environment when overapplied.
Carrier
Materials used to deliver the nutrients: clay based materials and water
Incorporated application
Mixing a surface-applied fertilizer into the soil
Essential nutrients for photosynthesis
N, P, K, Mn, Mg, S, Fe, Cl
Nitrogen compounds
N2 - Atmospheric NH3 - Ammonia NH4+ - Ammonium NO3- - Nitrate NO2- - Nitrite N2O - Nitrous Oxide
Nitrification inhibitors
Nitrate is negatively charged, susceptible to leaching Nitrification inhibitors slow the conversion of ammonium to nitrate
Macronutrients (elements needed in large amounts) (3)
Nitrogen, Phosphorus, Potassium
Diffusion
Nutrients move from higher concentration to lower concentration at the root
Common soil anions (negative charge) (5)
OH- (hydroxide), SO4 -2 (sulfate) Cl- (chloride), NO3 - (nitrate), H2PO4 - (dihydrogen phosphate)
Plant tissue analysis
Performed to verify visual deficiency symptoms and identify plant nutrient shortages before they appear
Foliar application
Placement of a fertilizer directly on the foliage (leaves/stems) of a crop (often used for specific micronutrient deficiencies)
Liming materials
Reduce soil acidity Ca2+ ions from aglime replace Al3+ at the exchange sites; Al reacts with water, releasing H+ Carbonate ions (CO3 2-) from aglime react in the soil solution, creating an excess of OH- which combine with H+ ions to form water
Root interception
Roots obtain nutrients by physically contacting nutrients in the soil solution of on soil surfaces
Salt index
Salt around seed reduces water uptake
Rhizobia
Soil bacteria that fix nitrogen after becoming established inside root nodules of legumes; must be kept in moderate temperatures, packages dated for viability; need to inoculate with Rhizobia if crop has not been previously grown in field
Polymer-coated urea
Solid urea or other nutrient core, coated with various polymers (plastics) Slows release of nitrogen Release depends on coat thickness, chemistry, temperature, and moisture
NV (neutralizing value)
The ability of lime to change the pH in the soil
Soil Fertility
The capacity of a soil to provide crops with essential plant nutrients
Leaching
The movement of a material/nutrient in a solution by the drainage of water through the soil
Broadcast application
The spreading of fertilizers (and/or pesticides) over an entire area of a field
Band application
The spreading of fertilizers (and/or pesticides) over, or next to, each row of plants or in bands in a field
Plant nutrition
The study of the chemical elements and compounds necessary for plant growth, plant metabolism, and their external supply
Soil solution
The water content of a soil, which is a solution containing various gases, organic matter, and minerals
Rate
Toxicity of ammonium or thiosulfate components of fertilizers
Urease Inhibitors
Urease breaks down urea More concern for volatilization loss in warm, high pH environment Urease inhibitors keep N as urea in soil (reduces volatilization)
CCE
as CCE increases, limestone can more easily change soil pH As particle size decreases, limestone can more easily change soil pH
Grid sampling
ignores field characteristics; Field is divided into a grid pattern (2.5 acre grids=1 hectare very common), subsamples often taken around each grid center