Term
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Definition
The amount of an element that will replace or combine with one mole of H+ (1.008 grams of H+)
=Atomic weight/Valence
ex:
Ca 2+ = 40.08g/2
Al 3+ = 26.98 g /3 |
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Term
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Definition
=equivalent weight / 1000
also
= atomic weight / (valence * 1000)
ex:
1 meq Ca 2+ / 100 g soil = ((40.08 g /2000) / 100g soil = .02 g Ca 2+ / 100 g soil |
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Term
| Centimole of Charge (cmolc) |
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Definition
= (Atomic weight / 100) / Valence
ex:
1 cmolc Ca 2+ = 40.08/200 = 0.20 g |
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Term
| Conversions between units |
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Definition
meq/100g soil = cmolc/kg soil
kg/ha = lb/ac
1 meq Ca / 100 g soil = 0.02 Ca / 100 g soil
0.02 g Ca / 100 g soil = x kg Ca / ha = x kg Ca / 2,000,000 kg soil
x = 400 kg Ca
CaCO3 has 40% Ca
1 t CaCO3 / ha = 400 kg Ca/ha = 1 meg Ca / 100 g soil |
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Term
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Definition
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Term
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Definition
1. montomorillonite and vermiculite
difference between these two is the amount of charge imbalance
2. Micas - potassium (exchangeable cation) in inter-layer region
3. Chlorite - Mg, Al, Fe in interlayer region. Not easily exchangable |
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Term
| Intergradient clay materials - Al |
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Definition
| Al - hard to move big chunks of Al hydroxide out. Not exchangable, and keeps interlayer region propped open, creating islands between layers |
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Term
| Intergradient clay materials - oxides and hydroxides of Fe |
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Definition
| variable charge surfaces in clay minerals, don't always fit silicate structure. at lower pH surface activity on outside with a lot of H+ |
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Term
| Cation Exchange Properties |
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Definition
traditional measurements:
wash a soil with NH4 acetate adjusted to pH 7.0
CEC = NH4 retained on exchange sites = sum of exchangeable Ca, Mg, K, Na and acidity |
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Term
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Definition
CEC at native soil pH - as plant sees it - wash soil with a neutral, unbuffered salt solution
ECEC= sum of exchangeable Ca, Mg, K, Na and acidity displaced by the KCl wash |
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Term
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Definition
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Term
| CEC Montmorillonite (smectite) |
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Definition
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Term
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Definition
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Term
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Definition
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Term
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Definition
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Term
| CEC intergradient clay minerals |
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Definition
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Term
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Definition
| the progressive development of an organism |
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Term
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Definition
1. seed germination
2. vegetative development
3. reproductive development
4. seed maturity |
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Term
| Implications to crop nutrient management |
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Definition
1. growth stages considered depend on harvested crop component. ex: forages, tobacco - vegetative growth. soybean, rice, corn, potato - seed or tuber production at maturity
2. how do different stages of growth impact harvested component?
ex: rice/wheat
grain yield = f (# tillers, #panicles, #seed/panicle, assimilate translocation to seed)
note: an early freeze or a drought may affect yields by interrupting translocation
see also, formulas for peach palm and soybean in packet |
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Term
| factors affecting plant growth 1 |
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Definition
1. genetic - fixed ranges manipulated through breeding
ex: acidity tolerance in sorghum and nitrogen response in rice |
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Term
| factors affecting plant growth 2 |
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Definition
2. environmental:
a. light
b. CO2
c. water
d. temperature
e. soil aeration
f. nutrients |
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Term
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Definition
light mediated
CO2 + 2H2O --> CH2O + H2O + O2 |
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Term
| Photosynthesis: effect of radiation |
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Definition
1. light intensity - C4 vs C3 metabolic systems explain diffs btwn plants
2. light compensation - compensation point - light intensity where CO2 fixed in photosynthesis equals that evolved during respiration
3. saturation - light intensity above which it is not rate limiting to photosynthesis (plateau point). Light saturation point increases with CO2 concentration. Canopy can shade lower leaves, thus making them below saturation point. Management of plant density and type of plant can maximize saturation. |
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Term
| Photosynthesis: effect of temperature |
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Definition
| 4. Temperature - the compensation point in light intensity increases with ambient temperature |
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Term
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Definition
| under moisture stress, leaf stomates close, limiting CO2 entry from atmosphere, thus reducing photosynthesis |
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Term
| Photosynthesis and leaf area index (LAI) |
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Definition
| measure of amount of leaf area to soil surface area. LAI of 4 means there is 4 times as much leaf area on the plant as soil area occupied by the plant. Max photosynthesis occurs where LAI value interception of light is maximized. Some crops can get a higher LAI over a longer period of time with N application. |
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Term
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Definition
| can restrict root proliferation and access to nutrients. response to fertilization is diminished. soil can be compacted by tillage and restrict root penetration into subsoils, limiting plant access to nutrients and soil water reserves |
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Term
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Definition
| plant roots and soil microbes respire. Aeration is the exchange of gases between the atmosphere, the soil and the roots. In well-drained soils aeration occurs through gas filled pore space. O2 could be limited by diff water table depths --> making pore space filled with water and not O2 |
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Term
| Essential nutrients criteria |
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Definition
1. involved directly in a metabolic process of the plant (such as N in protein and Mg in chlorophyll)
2. omission of the element results in abnormal growth, failure to complete life cycle, or premature death of the plant
3. no other chemical compound can replace the metabolic function of the element |
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Term
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Definition
quantity needed by plants is higher
1. C
2. H
3. O
4. N
5. P
6. K
7. Ca
8. Mg
9. S |
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Term
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Definition
quantity needed by plants is lower
1. Fe
2. Zn
3. Mn
4. Cu
5. B
6. Mo
7. Cl |
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Term
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Definition
| C, basic molecular component of carbohydrates, proteins, lipids and nucleic acids. Uptake form: CO2 |
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Term
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Definition
| H, important in ionic balance and as main reducing agent; key role in energy relations of cells. uptake form: H2O |
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Term
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Definition
| O, occurs in virtually all organic compounds in living organisms. uptake form: H2O, O2 |
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Term
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Definition
| N, component of organic compounds ranging from proteins to nucleic acids. uptake form: NH4+, NO3- |
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Term
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Definition
| P, energy transfer and protein metabolism. uptake form: H2PO4-, HPO4 2- |
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Term
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Definition
| K, osmotic and ionic regulation; cofactor or activator for many enzymes of carbohydrate and protein metabolism. uptake form: K+ |
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Term
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Definition
| Ca, cell division and maintenance of membrane integrity. uptake form: Ca 2+ |
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Term
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Definition
| Mg, chlorophyll component and cofactor for many enzyme reactions. uptage form: Mg 2+ |
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Term
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Definition
| S, component of proteins and enzymes; involved in plant cell energetics. uptake form: SO4 2-, SO2 |
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Term
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Definition
| Fe, component of enzymes and carriers; involved in N fixation, photosynthesis and electron transfer. uptake form: Fe 2+, Fe 3+ |
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Term
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Definition
| Zn, component of several enzymes. uptake form: Zn 2+ |
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Term
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Definition
| Mn, involved in O2 evolving system of photosynthesis; component of enzymes. uptake form: Mn 2+ |
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Term
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Definition
| Cu, constituent of many enzymes. uptake form: Cu 2+ |
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Term
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Definition
| B, carbohydrate metabolism and synthesis of cell wall components. uptake form: H3BO3 |
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Term
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Definition
| Mo, required for N assimilation; component of N2-fixation enzymes. uptake form: MoO4 2- |
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Term
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Definition
| Cl, activator of enzymes involved in splitting H2O in photosynthesis; osmoregulation of plants in saline soils. uptake form: Cl- |
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Term
| Measurements of plant growth response to nutrients |
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Definition
1. harvested component - yield
2. physical measurements:
a. root length - liming alleviates Al toxic effect on root elongation, gives plants better access to water as roots are able to grow deeper
b. plant height - good indicator of response to fertilizer P
c. dry weight distribution among plant components
d. leaf area - nutrient applications can increase leaf area for photosynthesis
3. Chemical determinations - analyze plant material for the nutrient which is under investigation. fertilizer --> uptake? Also, nutrient interactions, ie - N limiting ability of P uptake in corn. Measure photosynthesis and respiration and specific products like amino acids, carbs, etc.
4. growth analysis -
a. top:root ratio - where fertility treatment effect manifests in plant. favorable conditions: top growth. stress conditions: root growth.
b. crop growth rate - change in dry weight with respect to time. (W2 - W1)/ (t2 - t1)
c. relative growth rate - change in plant dry weight per unit of dry weight present (similar to acceleration)
d. net assimilation rate - change in dry weight per unit of leaf area per unit of time |
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