LCA Agriculture/Horticulture flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Slope gradient formula

Slope percent equals rise divided by run, multiplied by 100. Run is horizontal distance, so a 1 m rise over 10 m horizontal run is a 10% slope.

Aspect and microclimate

Aspect is the compass direction a slope faces. South-facing slopes receive more solar radiation, warm and dry earlier, and favor drought-tolerant plants; north-facing slopes stay cooler and moister.

Percolation test

A field test measuring how fast water level drops in a prepared hole. Results, usually reported in minutes per inch, determine whether soil can support a drainfield or infiltration system.

Utility locate tolerance zone

The marked band around buried utilities where excavation must be done by hand or non-destructive methods. Always confirm locates before digging to avoid striking lines.

Soil texture triangle

A USDA diagram that classifies soil by percent sand, silt, and clay. The three percentages must sum to 100, and the intersecting lines identify the textural class.

Cation exchange capacity

CEC measures a soil's capacity to hold positively charged nutrients such as calcium, magnesium, and potassium. It increases with clay and organic matter and is low in sands.

Plant-available water

The water held between field capacity and permanent wilting point. It is the portion of soil moisture plants can actually extract, and it is greater in loams than in sands.

Soil bulk density

The mass of dry soil per unit volume. High bulk density indicates compaction that restricts root growth, air movement, and water infiltration, commonly above 1.6 g/cm³ in loam.

Right plant, right place

Selecting species that match the site's light, soil moisture, pH, space, and climate. Correct matching reduces water, fertilizer, and pesticide inputs and lowers maintenance.

Root flare placement

The widened base of the trunk where roots begin. It must sit at or slightly above grade; burying it causes girdling roots and decline.

Nursery stock caliper

Trunk diameter measured at a specified height above the root flare, used with height, spread, and root ball size to grade nursery stock under ANSI Z60.1.

Pruning timing by bloom

Prune spring-flowering shrubs right after bloom because they set buds the previous season. Prune summer-flowering shrubs in late winter or early spring before new growth.

Distribution uniformity

A measure of how evenly an irrigation system applies water. It is commonly computed as the average of the lowest quarter of catch readings divided by the overall average.

Matched precipitation rate

A design condition where all heads in a zone apply water at the same rate, preventing wet and dry stripes. It requires coordinating nozzle flow, arc, and spacing.

Backflow prevention

A device or assembly that stops contaminated water from reversing into a potable supply. Required on irrigation connections, with the assembly type chosen by hazard level.

French drain

A perforated pipe set in washed gravel and wrapped with filter fabric, sloped to carry subsurface water away. It lowers the water table and relieves saturated soils.

Economic threshold

The pest density at which the cost of control equals the crop loss that would otherwise occur. It guides whether treatment is economically justified.

Disease triangle

A model stating disease requires a susceptible host, a virulent pathogen, and a favorable environment. Removing any one factor prevents or reduces disease development.

Pre-emergent herbicide

A product applied to soil before weed seeds germinate, forming a barrier that inhibits seedling growth. It does not control weeds already emerged.

Herbicide mode of action rotation

Alternating herbicide groups with different modes of action across seasons to slow the evolution of resistant weed populations. It is combined with cultural and mechanical controls.

Fertilizer N-P-K meaning

The three numbers are percent nitrogen, available phosphate expressed as P2O5, and soluble potash expressed as K2O by product weight. They are not elemental P and K.

P2O5 to elemental phosphorus

Multiply the P2O5 percentage by 0.44 to get elemental phosphorus. Similarly, multiply K2O by 0.83 to get elemental potassium for nutrient budgeting.

Fertilizer product rate

Divide the nutrient needed by the nutrient fraction in the product. For example, 2 kg of N from a 20% N product requires 2 ÷ 0.20 = 10 kg of product.

Fertilizer buffer setback

An unfertilized strip between application areas and waterways or impervious surfaces. It intercepts runoff and reduces nutrient movement into surface water.

Paver base compaction

Aggregate base is placed in thin lifts, commonly 50 to 75 mm, and compacted with a plate compactor. Thin lifts achieve specified density better than one deep layer.

Retaining wall drainage

Granular backfill, filter fabric, and weep holes or perforated pipe relieve hydrostatic pressure behind a wall. Poor drainage is a leading cause of wall failure.

Hardscape drainage slope

Paving is sloped away from buildings, typically around 1 to 2%, so water drains off the surface. Verify with a level and straightedge before finishing.

Chain saw kickback

A sudden upward reaction when the upper tip of the guide bar contacts an object. A chain brake, low-kickback chain, and proper stance reduce injury risk.

Two-stroke fuel mix

Two-stroke engines require gasoline mixed with oil at the manufacturer's ratio for lubrication. Four-stroke engines use straight gasoline with a separate crankcase oil supply.

Ladder 4:1 rule

For every four units of height, the ladder base sits one unit out from the wall. Maintain three points of contact and secure the top before climbing.

Change order

A written, signed amendment to a contract that modifies scope, price, or schedule. Work should not proceed on a change until it is documented and approved.

Silt fence installation

A sediment barrier installed on the contour with the bottom edge trenched and backfilled. It ponds runoff so sediment settles and must be inspected and repaired after storms.