Mixed Deck — All CCA Topics Flashcards

Which instrument is commonly used in the field to measure soil water matric potential and assist in irrigation scheduling?

Answer: Tensiometer

Tensiometers measure the matric potential (tension) with which water is held in the soil, providing a direct indicator of how hard plant roots must work to extract water and when irrigation is needed.

What is the primary benefit of conservation tillage in soil management?

Answer: Reduces soil erosion

Conservation tillage helps reduce soil erosion by maintaining crop residue on the soil surface, which protects the soil from wind and water erosion.

Which factor is most important when choosing crops for correctional institution farming?

Answer: Compatibility with local climate

Climate compatibility ensures the crop can thrive in the local conditions, reducing failure and resource waste.

Which cover crop species is BEST suited for scavenging residual nitrate from the soil profile following corn harvest?

Answer: Cereal rye

Cereal rye has an extensive root system, germinates in cold temperatures, and has high nitrate uptake capacity, making it ideal for fall nitrogen scavenging.

A nutrient management plan for a corn-soybean rotation includes organic matter decomposition credits. If a field has 3.5% organic matter, what approximate annual nitrogen credit (lbs N/ac) from mineralization is used in most Midwest state guidelines?

Answer: 20–35 lbs N/ac

Most Midwest guidelines credit approximately 20 lbs N/ac per 1% organic matter annually, so 3.5% OM yields roughly 20–35 lbs N/ac from mineralization.

What is the term for the water lost from the soil-plant system through both evaporation and plant transpiration?

Answer: Evapotranspiration

Evapotranspiration (ET) combines soil evaporation and plant transpiration and is a key measure for irrigation scheduling.

Sulfur deficiency in crops is most commonly associated with which of the following soil and environmental conditions?

Answer: Sandy, low-organic-matter soils in areas with reduced atmospheric sulfur deposition

Sulfur deficiency has increased as atmospheric SO2 deposition declined; coarse, low-OM soils hold little sulfate and are most vulnerable.

Which fertilizer application method is most appropriate for correcting zinc deficiency observed mid-season in corn?

Answer: Foliar application of zinc sulfate or zinc chelate solution

Mid-season foliar application of soluble zinc sources provides rapid correction of zinc deficiency since root uptake is slow when soil conditions limit zinc availability.

Which of the following describes the concept of 'harvest index' in crop science?

Answer: The ratio of harvestable product (grain) to total aboveground biomass

Harvest index (HI) is the proportion of total above-ground dry matter partitioned into the harvested organ (grain), typically ranging from 0.45–0.55 in modern corn.

Which of the following is a liming material rather than a fertilizer, but is often applied to improve nutrient availability?

Answer: Calcitic limestone (CaCO3)

Calcitic limestone is a liming material that raises soil pH, improving the availability of most macro and micronutrients rather than supplying large amounts of plant-available nutrients directly.

A grower is selecting a fertilizer for an in-furrow (pop-up) application at planting. Which of the following common fertilizer sources has the highest salt index, posing the greatest risk of seedling injury if applied at excessive rates?

Answer: Potassium Chloride (KCl)

The salt index measures a fertilizer's effect on the osmotic potential of the soil solution. A high salt index can cause 'fertilizer burn' by drawing moisture out of seedling roots. Potassium chloride (0-0-60), also known as muriate of potash, has one of the highest salt indices among common fertilizers (around 116) and must be used with extreme caution for in-furrow applications. By comparison, Urea is high (75), MAP is low (30), and TSP is very low (10).

When computing a nitrogen budget using the maximum return to nitrogen (MRTN) approach, the primary economic inputs are:

Answer: Corn price and nitrogen fertilizer cost

MRTN calculations identify the N rate that maximizes profit by comparing the cost of N fertilizer against the value of the resulting yield response.

Which of the following is the best example of biological weed control in US crop production?

Answer: Releasing Rhinocyllus conicus weevils to suppress musk thistle

Rhinocyllus conicus is a seed head weevil introduced as a classical biocontrol agent for musk thistle (Carduus nutans), a noxious invasive weed.

Which tillage system typically results in the LEAST surface residue after planting?

Answer: Conventional tillage

Conventional tillage inverts the soil with a moldboard plow, burying most surface residue and leaving the surface bare.

Which scenario BEST describes a situation where drip irrigation would be preferred over overhead center pivot irrigation in a crop management system?

Answer: High-value vegetable or fruit crops on irregular terrain where foliar disease management is critical

Drip irrigation delivers water directly to the root zone without wetting foliage, reducing disease pressure and making it economically justified for high-value crops on varied terrain.

A constructed pond built across a drainage way to intercept runoff and allow sediment to settle is called a:

Answer: Sediment basin

A sediment basin is specifically designed to trap sediment from runoff before water leaves the field or construction site.

A CCA is interpreting a base saturation report showing Ca=65%, Mg=10%, K=3%, Na=1%, and H=21%. What is the approximate CEC of this soil if calcium is 1,300 lbs/ac in the top 6 inches?

Answer: 16 meq/100g

Ca at 65% saturation = 1,300 lbs/ac; Ca contributes 2 meq per mmol, and 1,300 lbs/ac Ca ÷ 400 lbs per meq/100g = ~CEC 16 meq/100g (using the standard 2 million lbs/ac furrow slice).

Strip-till is best described as a system that:

Answer: Tills only narrow bands where seeds will be placed, leaving inter-row residue intact

Strip-till disturbs only the planting zone, preserving inter-row residue for erosion control while warming the seedbed.

Why is soil testing essential before planting crops?

Answer: Determines fertilizer needs

Soil testing reveals pH and nutrient levels, guiding proper fertilization and improving plant health outcomes.

A crop consultant recommends intercropping corn and squash using the Three Sisters system. The primary agronomic advantage of this system is:

Answer: Diverse species use space, light, and nutrients complementarily, reducing weed pressure and improving system productivity

The Three Sisters system uses complementary niches — corn for vertical structure, beans for nitrogen fixation, and squash for ground cover — to maximize overall system productivity.