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