ACS CCN1 flashcards
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32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Cation exchange capacity
- The total quantity of exchangeable cations a soil can hold, expressed in cmol(+)/kg or meq/100 g, governed mainly by clay type and organic matter.
- Base saturation
- The percentage of the cation exchange capacity occupied by basic cations (Ca, Mg, K, Na), calculated as basic cations divided by CEC times 100.
- Law of the Minimum
- The principle that crop yield is limited by the essential nutrient in shortest supply relative to need, not by total nutrient availability.
- Mobile vs immobile nutrients
- Mobile nutrients such as N, K, and Mg show deficiency in older leaves first; immobile nutrients such as Ca, Fe, and B show it in new growth.
- Fertilizer grade conversion
- Elemental P equals percent P2O5 times 0.44, and elemental K equals percent K2O times 0.83, used to convert oxide guarantees to elemental amounts.
- Urea volatilization
- Urea hydrolyzes to ammonium and, if left on the surface without incorporation or rainfall, can lose nitrogen as ammonia gas.
- DAP and MAP
- Diammonium phosphate (18-46-0) and monoammonium phosphate (11-52-0) are high-analysis materials supplying both nitrogen and phosphorus.
- Limestone neutralizing value
- The acid-neutralizing capacity of a liming material, expressed as calcium carbonate equivalent and adjusted for fineness of grind.
- Gypsum as amendment
- Calcium sulfate dihydrate that supplies calcium and sulfur without raising soil pH and can help displace excess sodium.
- Composite soil sample
- A sample made by mixing 15 to 20 subsamples from a uniform management zone to represent the field average for laboratory analysis.
- Soil test P and K units
- Extractable phosphorus and potassium are reported in ppm; multiplying ppm by 2 gives pounds per acre in the top 6 to 8 inches.
- Soil test calibration
- The process relating extractable soil test levels to crop yield response and to the fertilizer rates needed to reach sufficiency.
- Tissue sufficiency range
- The range of nutrient concentrations in a defined plant part at a specific growth stage associated with healthy, non-limiting crop growth.
- Presidedress nitrate test
- An in-season soil nitrate measurement used to adjust nitrogen sidedress rates based on nitrogen already available in the root zone.
- Buffer pH and lime requirement
- Buffer pH measures soil reserve acidity and is used to estimate the amount of lime needed to raise pH to a target level.
- 4R nutrient stewardship
- The framework of applying the right nutrient source at the right rate, right time, and right place to meet crop needs and reduce losses.
- Banded fertilizer placement
- Placing fertilizer in concentrated bands below or beside the soil surface near roots, improving phosphorus and potassium efficiency over broadcast application.
- Split nitrogen application
- Dividing total nitrogen into two or more applications during the season to match crop uptake and reduce leaching and denitrification losses.
- Starter fertilizer placement
- A small nutrient application placed near but not in contact with the seed, typically in a 2 by 2 band to avoid salt injury.
- Legume nitrogen credit
- The nitrogen contribution from a preceding legume crop that must be subtracted from the planned fertilizer nitrogen rate.
- Nitrate leaching
- The downward movement of soluble nitrate below the root zone with percolating water, a major nitrogen loss pathway in coarse or wet soils.
- Denitrification
- The microbial conversion of nitrate to nitrogen gases under saturated, low-oxygen soil conditions, causing nitrogen loss and nitrous oxide emissions.
- Nitrification inhibitor
- A compound that slows the microbial conversion of ammonium to nitrate, reducing nitrate leaching and denitrification losses.
- Urease inhibitor
- A compound that delays urea hydrolysis, reducing ammonia volatilization when urea cannot be incorporated promptly.
- Phosphorus loss pathways
- Phosphorus moves mainly with eroded sediment and in runoff as dissolved phosphorus, so erosion control is central to reducing loss.
- Riparian buffer strip
- Vegetated land adjacent to water that traps sediment-bound phosphorus and takes up nitrate before runoff reaches streams.
- Boron and calcium mobility
- Both are largely immobile in plants, so deficiency symptoms appear in new growth and can cause fruit disorders such as blossom-end rot.
- Nitrogen and crop quality
- Nitrogen drives vegetative growth and protein; excess nitrogen can delay maturity, reduce lodging resistance, and lower quality in some crops.
- Potassium and crop quality
- Potassium supports stalk strength, drought tolerance, and fruit quality, with crop demand peaking during reproductive growth stages.
- Anhydrous ammonia safety
- A toxic, corrosive compressed gas requiring pressure-rated equipment, trained operators, personal protective equipment, and emergency response planning.
- Economic optimum nitrogen rate
- The nitrogen rate where the marginal cost of the last unit of nitrogen equals the marginal value of the yield it produces.
- Nutrient use efficiency
- The ratio of crop nutrient uptake or yield produced to nutrient supplied; higher values indicate less nutrient lost per unit of production.