Free International CCA Exam Flashcards

Carbon, hydrogen, and oxygen; the primary macronutrients nitrogen, phosphorus, and potassium; the secondary nutrients calcium, magnesium, and sulfur; and the micronutrients boron, chlorine, copper, iron, manganese, molybdenum, nickel, and zinc.

Mass flow carries dissolved nutrients with water moving toward roots. Diffusion moves nutrients down a concentration gradient toward depleted root zones. Root interception occurs as growing roots physically contact new soil surfaces.

Mineralization converts organic nitrogen into plant-available ammonium. Immobilization is the reverse short-term pathway: microbes take up inorganic nitrogen and incorporate it into organic biomass, temporarily reducing crop availability.

Under aerobic conditions, microbes oxidize ammonium to nitrite and then nitrate. Nitrate is readily available to plants but is mobile and susceptible to leaching or denitrification; the process also contributes acidity.

Risk is greatest when nitrate, readily decomposable carbon, warm temperatures, and oxygen-limited conditions coincide—often in saturated or poorly drained soil. Microbes reduce nitrate to gaseous nitrogen forms that can leave the field.

Warm conditions, moist surface residue, high surface pH, and leaving urea unincorporated raise risk. Timely incorporation, sufficient rainfall or irrigation to move urea into soil, or an appropriate stabilizer can reduce loss.

Negatively charged clay and organic-matter surfaces retain positively charged ions such as potassium, calcium, magnesium, and ammonium. A higher CEC generally increases cation buffering; it does not comparably retain mobile anions such as nitrate.

Use a consistent depth, collect enough cores in a defensible random, grid, or management-zone pattern, combine only areas with similar history and conditions, and keep unusual spots separate. Avoid fertilizer bands and contamination unless they are the sampling target.

A calibrated soil test estimates the soil's nutrient-supplying status and helps plan inputs. Tissue analysis shows what the crop has actually taken up at a defined growth stage. Either result needs field history, sampling quality, and crop symptoms for interpretation.

Soil pH measures current active acidity. Buffer pH estimates reserve acidity and the soil's resistance to pH change, so it helps determine lime requirement. Two soils with the same soil pH can require different lime rates.

Its calcium carbonate equivalent measures chemical neutralizing capacity, while particle fineness affects reaction rate. Effective neutralizing value combines these factors; application rate comparisons should use effective material, not product weight alone.

Right source matches nutrient form to crop and site; right rate matches crop need and soil supply; right time synchronizes availability with demand; right place positions nutrients for uptake while limiting loss. The four decisions work as a system.

Divide the nutrient requirement by the nutrient fraction: 120 ÷ 0.46 = about 261 lb of product. Always convert the fertilizer grade percentage to a decimal before calculating.

The relative percentages of sand, silt, and clay in the fine-earth fraction determine texture on the textural triangle. Texture is a particle-size property and is not changed simply by tillage or compaction.

Texture describes the proportions of sand, silt, and clay. Structure describes how those particles and organic materials form aggregates. Management can improve or degrade structure even though the underlying texture remains the same.

Bulk density is oven-dry soil mass divided by total bulk volume. For the same particle density, a higher bulk density means lower total porosity and often more compaction, with possible restrictions on rooting, aeration, and infiltration.

Plant-available water is approximately the water held between field capacity and permanent wilting point. Field capacity follows drainage of excess gravitational water; at permanent wilting point, remaining water is held too tightly for the crop to recover.

Infiltration is water entering the soil surface. Percolation is its subsequent downward movement through the profile. Surface sealing can limit infiltration, while a restrictive subsurface layer can slow percolation even after water enters.

Combine field evidence—root restriction, ponding, wheel-track patterns, or poor emergence—with measurements such as bulk density or penetration resistance at comparable moisture. Then identify depth and cause before choosing traffic control, biological improvement, or tillage.

Sheet erosion removes a thin, relatively uniform layer. Rill erosion forms small flow channels that normal tillage can erase. Gully erosion creates larger channels that normal tillage cannot remove and requires concentrated-flow control.

A is predicted average annual soil loss; R is rainfall erosivity; K is soil erodibility; LS combines slope length and steepness; C is cover-management; and P is supporting conservation practice. Reducing C or P can lower predicted loss on a fixed site.

Cover intercepts raindrop energy, slows overland flow, increases surface roughness, and often improves aggregation and infiltration. Those effects reduce both soil detachment and transport.

Contouring places operations across the slope to slow runoff. Strip cropping alternates protective and erosion-prone crops to shorten flow paths. Buffers trap sediment and slow flow before it reaches a sensitive area; none substitutes for controlling concentrated gullies.

A survey maps soil associations at a stated scale, so inclusions and boundary uncertainty are expected. Field observations, sampling, slope, drainage, and rooting restrictions confirm whether the mapped interpretation fits the exact management area.

Estimate crop water use, account for effective rainfall, measure or estimate root-zone water, know the soil's available-water capacity and allowable depletion, and consider system application rate and efficiency. Apply enough to refill the managed root zone without avoidable runoff or deep drainage.

Salinity is excess soluble salts, commonly assessed with electrical conductivity, and primarily creates osmotic stress. Sodicity is excessive exchangeable sodium, assessed with measures such as SAR or ESP, and can disperse clay, destroy structure, and restrict infiltration.

IPM combines correct identification, monitoring, thresholds, prevention, and compatible cultural, biological, mechanical, and chemical tactics. Decisions consider economics, efficacy, resistance, worker safety, and environmental effects rather than relying automatically on one control.

Insects, diseases, weeds, nutrient disorders, herbicide injury, weather, and compaction can produce similar symptoms. Confirming the causal agent and vulnerable stage prevents an ineffective treatment and helps avoid worsening a non-pest problem.

Use a pattern and sample unit suited to the pest's distribution, examine enough locations across the management area, record pest and beneficial stages plus crop injury, and avoid sampling only field edges or obvious hot spots unless separately evaluating them.

The economic injury level is the lowest pest density at which expected loss equals control cost. The economic threshold is the earlier action point chosen so treatment can prevent the population from reaching that injury level.

A susceptible host, a virulent pathogen, and a favorable environment must coincide over sufficient time for disease to develop. Management can reduce risk by changing any side—for example resistance, inoculum reduction, or canopy-moisture management.

Complete metamorphosis has egg, larva, pupa, and adult stages; larvae often look and feed differently from adults. Incomplete metamorphosis has egg, nymph, and adult stages; nymphs resemble smaller wingless adults and lack a pupal stage.

Annuals reproduce by seed within one year, biennials usually grow vegetatively the first year and reproduce the second, and perennials persist through vegetative structures as well as seed. Preventing seed production and exhausting perennial reserves require different timing strategies.

Examples are crop rotation or competitive stands (cultural), cultivation or trapping (mechanical), conserving predators or using a biocontrol organism (biological), and applying a labeled pesticide (chemical). An IPM plan combines compatible tactics for the site.

Different products can share the same mode-of-action group and select for the same resistance mechanism. Rotate effective modes of action, use labeled rates and timing, limit repeated selection, and combine nonchemical tactics where practical.

The label defines legal uses and restrictions, including crop and target, rate, timing, PPE, buffers, reentry, preharvest interval, and disposal. A recommendation must fit the current label and applicable law; prior practice does not override it.

High water solubility, persistence, and weak adsorption to soil can increase downward movement, especially with permeable soil, shallow groundwater, and heavy water input. Strong adsorption can reduce leaching but may increase transport with eroded sediment.

The REI is the time after application before workers may enter a treated area without specified protections. The PHI is the minimum time between application and harvest. Both are label-specific and serve different exposure controls.

Rotation can interrupt host-specific pests, diversify herbicide and tillage options, improve residue and rooting patterns, spread labor and weather risk, and alter nutrient demand. Benefits depend on the crops and sequence; merely changing varieties may not break a pest cycle.

Match maturity and yield stability to the growing season, then consider soil and drainage adaptation, pest resistance, standability, quality traits, expected management, market requirements, and independent multi-location performance—not yield from one favorable trial alone.

An F1 hybrid is the controlled first-generation cross of selected parents and is genetically uniform. Its offspring segregate for parental traits, so saved F2 seed can vary in maturity, form, quality, and yield rather than remaining true to the hybrid.

PLS percentage = purity percentage × germination percentage ÷ 100. For seed that is 96% pure and 85% germinating, PLS = 81.6%; a bulk seeding rate must be adjusted upward to deliver the intended amount of live seed.

Required seeds = target established plants ÷ expected establishment fraction. Convert seeds to weight with seeds per unit weight, then account for field area. Lower expected emergence or fewer seeds per pound requires more product for the same target stand.

Place seed where moisture and temperature support rapid germination while the seedling can still emerge. Seed size, soil texture, crusting risk, residue, planter performance, and forecast conditions matter; planting deeper is not a universal cure for dry surface soil.

Nutrient demand, pest susceptibility, crop safety, and label timing change during development. A standard staging system communicates actual plant development more reliably than calendar date or plant height alone.

At physiological maturity, the crop has completed dry-matter accumulation in the harvested organ. Harvest maturity occurs when moisture, field losses, quality, and equipment conditions make harvest practical; it may be later and can be accelerated by drying.

Randomization prevents treatment placement from being systematically confounded with field trends. Replication estimates natural variability and makes treatment comparisons more reliable. Side-by-side strips without either can mistake spatial variation for a treatment effect.

At its stated probability level, the LSD is the minimum difference between treatment means needed to call them statistically different in that trial. A difference smaller than the LSD is not proven; statistical significance still does not guarantee economic importance.

GPS supplies field position. GIS stores and analyzes spatial layers such as soil, yield, and elevation. Variable-rate technology uses a prescription or sensor input to change an application by location; its value depends on accurate data, calibration, and a responsive field factor.

Warm, wet grain accelerates respiration, mold, insects, and spoilage. Drying lowers moisture to a safe level for the crop and storage period; aeration manages temperature and moisture migration but is not a substitute for adequate drying.