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SACE Stage 2 Agricultural Production study materials
SACE Stage 2 Agricultural Production study resources

SACE Stage 2 Agricultural Production practice questions

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Question 1Agricultural Production

Which soil characteristic most directly determines the amount of plant-available water a soil can hold?

  1. The concentration of soluble salts in the soil
  2. The slope of the paddock
  3. The depth of the water table below the surface
  4. The proportion of clay and organic matter in the soil Correct answer.

Explanation

Plant-available water depends mainly on texture and organic matter, because fine particles and humus create small pores that retain water against drainage while still releasing it to roots. Sandy soils hold little water, whereas clay-rich and organic soils hold much more. Salinity, water-table depth and slope affect water supply but not the storage capacity itself.

Question 2Agricultural Production

A farmer wants to reduce wind erosion on a bare paddock over summer. Which practice is most effective?

  1. Maintaining surface cover such as stubble or a cover crop Correct answer.
  2. Irrigating heavily once at the start of summer
  3. Increasing the stocking rate to trample the surface
  4. Cultivating the surface to create a rough, loose seedbed

Explanation

Wind erosion occurs when bare, dry, fine particles are exposed to wind above the threshold velocity. Keeping the surface covered with stubble or a growing cover crop shields particles and reduces wind speed at the soil surface. Cultivation and trampling break down aggregates and increase the risk of loss.

Question 3Agricultural Production

In a legume-based pasture, which process supplies nitrogen to the grazing system?

  1. Leaching of ammonium from subsoil layers
  2. Breakdown of soil minerals releasing nitrate
  3. Symbiotic fixation of atmospheric nitrogen by rhizobia in root nodules Correct answer.
  4. Volatilisation of ammonia from urine patches

Explanation

Legumes such as clover and lucerne form nodules with rhizobia that convert atmospheric nitrogen into forms the plant can use. When the legume is grazed or senesces, this nitrogen enters the soil nitrogen pool. Mineral weathering, leaching and volatilisation do not add new nitrogen from the atmosphere.

Question 4Agricultural Production

Which statement best describes the purpose of a rotation that alternates cereals with a break crop?

  1. It removes the need for any fertiliser application
  2. It ensures the same herbicide can be used every year
  3. It interrupts pest and disease cycles and improves soil condition Correct answer.
  4. It guarantees higher prices for the cereal crop

Explanation

A break crop changes the host plant available to pathogens and pests, so populations decline between cereal crops. Diverse rotations also improve soil structure, weed control options and nutrient cycling. Rotations do not remove the need for fertiliser or guarantee prices.

Question 5Agricultural Production

A producer records the following for a mob of steers over one month: initial liveweight 400 kg, final liveweight 430 kg, and the mob consumes 3000 kg of dry matter. What is the feed conversion ratio?

  1. 3:1
  2. 30:1
  3. 10:1 Correct answer.
  4. 100:1

Explanation

Weight gain is 30 kg and dry matter intake is 3000 kg. Feed conversion ratio equals intake divided by gain, giving 3000 divided by 30, which is 100:1 expressed as kg feed per kg gain. The other values arise from misplacing the decimal or confusing gain with intake.

Question 6Agricultural Production

A soil test shows pH 4.8 in a paddock intended for a sensitive cereal crop. Which management response is most appropriate?

  1. Apply gypsum to increase calcium levels
  2. Deep-rip the soil to mix the profile
  3. Apply nitrogen fertiliser to stimulate growth
  4. Apply agricultural lime and monitor pH over subsequent seasons Correct answer.

Explanation

A pH of 4.8 indicates strong acidity that limits nutrient availability and can cause aluminium toxicity. Agricultural lime neutralises acidity and raises pH, but it reacts slowly, so application should be followed by monitoring. Gypsum supplies calcium and sulfur but has little effect on pH.

Question 7Agricultural Production

Which grazing strategy is most likely to improve pasture persistence on a heavily grazed paddock?

  1. Rotational grazing with adequate rest periods between grazings Correct answer.
  2. Grazing only during flowering to reduce seed set
  3. Continuous set stocking at a high rate throughout the year
  4. Removing all stock and never grazing the paddock again

Explanation

Rotational grazing allows plants to recover leaf area and replenish root reserves before being grazed again, which supports persistence. Continuous heavy stocking depletes reserves and weakens plants. Rest periods are the key mechanism, not total exclusion or grazing at flowering.

Question 8Agricultural Production

A grower applies 120 kg of urea per hectare, which contains 46% nitrogen. How much nitrogen is applied per hectare?

  1. 120 kg
  2. 46 kg
  3. 26 kg
  4. 55 kg Correct answer.

Explanation

Nitrogen applied equals product rate multiplied by nitrogen concentration, so 120 kg multiplied by 0.46 gives about 55 kg of nitrogen per hectare. The other figures confuse the concentration with the total or misapply the percentage.

Question 9Agricultural Production

Which practice best reduces nitrate leaching from a paddock after a heavy autumn rainfall?

  1. Applying nitrogen fertiliser just before the rain
  2. Leaving the paddock bare and fallow
  3. Establishing a fast-growing cover crop to take up residual nitrogen Correct answer.
  4. Deep ploughing to bury surface organic matter

Explanation

Nitrate is mobile and moves with water through the profile. A fast-growing cover crop takes up residual nitrate into plant tissue, reducing the amount available to leach. Applying fertiliser before heavy rain increases the pool at risk, and bare fallow leaves nitrate exposed to leaching.

Question 10Agricultural Production

A dairy farmer wants to estimate pasture intake of a herd. Which measurement is essential?

  1. The number of paddocks on the farm
  2. Pre-grazing and post-grazing pasture mass plus the grazed area Correct answer.
  3. The colour of the pasture at grazing
  4. The age of the pasture

Explanation

Pasture intake is estimated from the difference between pre-grazing and post-grazing herbage mass, multiplied by the area grazed and adjusted for the number of animals. These measurements account for the feed actually removed. Colour, paddock number and pasture age do not quantify intake.

Question 11Agricultural Production

Which of the following is an example of biological pest control in an integrated management program?

  1. Releasing a predatory mite to suppress a pest mite population Correct answer.
  2. Applying a broad-spectrum insecticide at calendar intervals
  3. Burning crop residue to destroy overwintering pupae
  4. Planting a single susceptible variety over a large area

Explanation

Biological control uses living organisms such as predators, parasitoids or pathogens to reduce pest populations. Releasing a predatory mite is a direct example. Calendar spraying, residue burning and monoculture are chemical, cultural and genetic approaches rather than biological control.

Question 12Agricultural Production

Which factor most strongly influences the rate of organic matter breakdown in soil?

  1. Temperature, moisture and the carbon-to-nitrogen ratio of the residue Correct answer.
  2. The number of earthworm species present
  3. The depth of the plough layer
  4. Soil colour and particle density

Explanation

Decomposition is driven by microbial activity, which responds strongly to temperature, moisture and the quality of the residue. Residues with a high carbon-to-nitrogen ratio break down more slowly because microbes must obtain more nitrogen. Colour and plough depth are not primary drivers.

Question 13Agricultural Production

A crop shows interveinal yellowing on older leaves while veins remain green, and a soil test indicates high pH. Which nutrient deficiency is most likely?

  1. Manganese
  2. Iron
  3. Magnesium Correct answer.
  4. Copper

Explanation

Magnesium is mobile in the plant, so deficiency appears first on older leaves as interveinal chlorosis. Iron and manganese are immobile and typically show symptoms on young leaves. Copper deficiency usually causes distortion and poor grain set rather than this pattern.

Question 14Agricultural Production

Which statement correctly describes the role of a shelterbelt on a farm?

  1. It reduces wind speed and can lower evaporation and stock stress Correct answer.
  2. It increases soil salinity by blocking drainage
  3. It eliminates the need for irrigation
  4. It increases wind speed at the leeward edge

Explanation

A shelterbelt slows wind across a protected zone downwind, reducing evaporation, wind erosion and cold stress on stock and crops. It does not remove the need for irrigation and may affect salinity only indirectly through changes in water balance.

Question 15Agricultural Production

A farmer is choosing between two crops with the same expected yield but different input costs and prices. Which approach best supports the decision?

  1. Comparing gross margins, calculated as income minus variable costs Correct answer.
  2. Choosing the crop with the lowest seed cost
  3. Selecting the crop that was grown last season
  4. Selecting the crop with the highest gross income regardless of costs

Explanation

Gross margin analysis compares the income from each enterprise after deducting variable costs, giving a measure of profitability per hectare. It accounts for both price and cost differences rather than one factor alone. Lowest seed cost or past practice may not maximise returns.

Question 16Agricultural Production

Which of the following best describes the purpose of a soil test in a fertiliser program?

  1. To replace the need for plant tissue testing entirely
  2. To determine the exact crop yield for the coming season
  3. To estimate available nutrient levels and guide application rates Correct answer.
  4. To identify the species of soil microbes present

Explanation

Soil tests measure extractable nutrient levels and other chemical properties, providing a basis for deciding application rates. They cannot predict yield exactly and are usually complemented by tissue tests. They are not designed to identify microbial species.

Question 17Agricultural Production

A producer observes that a flock's condition score is declining despite adequate pasture availability. Which explanation is most plausible?

  1. The flock has been drenched recently
  2. The flock is grazing in the morning
  3. The pasture is rank and low in digestibility Correct answer.
  4. The paddock has a gentle slope

Explanation

Pasture availability does not guarantee adequate nutrition if the feed is rank and low in digestibility, with high fibre and low protein. Animals cannot extract enough energy from such feed and lose condition. Recent drenching, slope and grazing time do not explain a decline under adequate availability.

Question 18Agricultural Production

In a controlled traffic farming system, which outcome is expected?

  1. Uniform soil disturbance across the whole paddock
  2. Elimination of the need for crop rotation
  3. Increased compaction across the entire paddock
  4. Concentration of compaction to permanent wheel tracks Correct answer.

Explanation

Controlled traffic confines machinery to permanent lanes so that most of the paddock is not compacted by wheels. This protects soil structure in the crop zone and improves infiltration. It does not remove the need for rotation or disturb the whole paddock.

Question 19Agricultural Production

Which practice is most likely to reduce the risk of herbicide resistance developing in a weed population?

  1. Spraying only when weeds are mature
  2. Rotating herbicide groups and integrating non-chemical control Correct answer.
  3. Using the same herbicide group repeatedly at full rate
  4. Applying reduced rates of a single herbicide

Explanation

Herbicide resistance is selected for when the same mode of action is used repeatedly. Rotating herbicide groups and combining them with cultural controls such as cultivation or crop competition reduces selection pressure. Reduced rates and late spraying increase the risk of survivors.

Question 20Agricultural Production

Which of the following best explains why stubble retention can improve soil water storage in a dryland cropping system?

  1. Stubble increases the rate of evaporation from the soil surface
  2. Stubble prevents any water from entering the soil
  3. Stubble adds large amounts of nitrogen to the soil immediately
  4. Stubble reduces runoff and evaporation, allowing more water to infiltrate Correct answer.

Explanation

Retained stubble protects the soil surface from raindrop impact, improves infiltration and reduces evaporation losses. This leaves more water stored in the profile for the following crop. Stubble does not prevent water entry and its nitrogen release is slow.

Question 21Agricultural Production

Which statement about the use of legumes in a pasture mix is correct?

  1. Legumes compete with grasses for water and should never be sown together
  2. Legumes can improve feed quality and reduce reliance on nitrogen fertiliser Correct answer.
  3. Legumes are only useful in tropical environments
  4. Legumes reduce the protein content of the pasture

Explanation

Legumes typically have higher protein and digestibility than grasses and fix atmospheric nitrogen, reducing the need for nitrogen fertiliser. They are used in a wide range of environments and are commonly sown with grasses to balance the sward.

Question 22Agricultural Production

A farmer wants to reduce the risk of groundwater contamination from a nitrogen fertiliser application. Which timing is most appropriate?

  1. Applying to bare soil in winter
  2. Applying before a forecast heavy rainfall event
  3. Applying when the crop is actively growing and demand is high Correct answer.
  4. Applying to waterlogged soil

Explanation

Applying nitrogen when the crop is actively growing maximises uptake and reduces the amount left in the soil to leach. Heavy rain, waterlogging and bare winter soil all increase the risk that nitrate moves below the root zone.

Question 23Agricultural Production

Which of the following is the most direct measure of soil compaction in a paddock?

  1. Soil colour in the topsoil
  2. Penetrometer resistance readings at depth Correct answer.
  3. The number of plant species present
  4. The pH of the surface soil

Explanation

A penetrometer measures the resistance of soil to penetration, which increases when soil is compacted. Readings at depth can reveal compacted layers. Colour, species number and pH do not directly measure compaction.

Question 24Agricultural Production

A grower is comparing two irrigation schedules. Schedule A applies small amounts frequently, while Schedule B applies larger amounts less often. Which statement is most accurate?

  1. Schedule A is unsuitable on sandy soils
  2. Schedule A always uses less water overall
  3. Schedule B guarantees higher yields
  4. Schedule B may encourage deeper root growth but risks greater deep drainage on light soils Correct answer.

Explanation

Larger, less frequent applications can wet the profile more deeply and encourage roots to grow down, but on light soils water may drain below the root zone. Small frequent applications keep the surface moist but can promote shallow roots. Neither schedule guarantees lower total water use or higher yields.

Question 25Agricultural Production

Which of the following best describes the concept of carrying capacity in a grazing system?

  1. The weight of a single animal at sale
  2. The amount of fertiliser applied per hectare
  3. The number of paddocks on a property
  4. The maximum number of animals a pasture can support sustainably over time Correct answer.

Explanation

Carrying capacity is the stocking rate a pasture can sustain without degrading the resource, balancing pasture growth with animal demand. It is expressed in animals or dry sheep equivalents per hectare. Paddock number, sale weight and fertiliser rate are different measures.

Question 26Agricultural Production

Which soil structure type generally provides the best combination of drainage and root penetration for most agricultural crops?

  1. Platy structure with horizontal layers
  2. Crumb structure with stable aggregates Correct answer.
  3. Massive structure with no visible peds
  4. Single-grain structure of loose sand

Explanation

A crumb structure consists of small, rounded, water-stable aggregates that create pore spaces for air, water and roots. These pores allow rapid drainage while retaining moisture in micropores, supporting healthy root growth.

Question 27Agricultural Production

Which term describes the loss of nitrogen from soil as ammonia gas into the atmosphere?

  1. Volatilisation Correct answer.
  2. Leaching
  3. Denitrification
  4. Nitrification

Explanation

Volatilisation is the conversion of ammonium nitrogen to ammonia gas, which is then lost to the atmosphere. It is most common when ammonium-based fertilisers are surface-applied to warm, moist, alkaline soils.

Question 28Agricultural Production

A producer wants to estimate the dry matter content of a pasture sample. Which method is most appropriate?

  1. Weighing the fresh sample and multiplying by two
  2. Measuring the height of the pasture before cutting
  3. Placing the sample in a sealed bag at room temperature
  4. Oven drying the sample at 60-70 degrees Celsius to constant weight Correct answer.

Explanation

Dry matter is determined by removing all moisture from a sample, usually in a forced-draught oven at 60-70 degrees Celsius until the weight becomes constant. The remaining mass represents the dry matter fraction.

Question 29Agricultural Production

Which livestock reproductive measure refers to the proportion of females exposed to a sire that give birth?

  1. Growth rate
  2. Condition score
  3. Weaning weight
  4. Lambing or calving percentage Correct answer.

Explanation

Lambing or calving percentage expresses the number of offspring born relative to the number of females joined. It is a key indicator of flock or herd reproductive efficiency.

Question 30Agricultural Production

Which practice is most effective for controlling wind erosion on a sandy paddock?

  1. Removing all crop residue after harvest
  2. Deep ploughing to bring clay to the surface
  3. Maintaining surface cover with stubble or a cover crop Correct answer.
  4. Applying nitrogen fertiliser before seeding

Explanation

Wind erosion occurs when bare, dry soil particles are lifted and transported by wind. Maintaining surface cover with stubble or a cover crop shields the soil surface and reduces wind velocity at ground level.

Question 31Agricultural Production

Which nutrient is most commonly deficient in Australian agricultural soils and is supplied by superphosphate?

  1. Phosphorus Correct answer.
  2. Calcium
  3. Potassium
  4. Sulfur

Explanation

Superphosphate is a phosphorus-based fertiliser applied widely in Australian agriculture to correct phosphorus deficiency. Phosphorus is essential for root development, energy transfer and seed formation.

Question 32Agricultural Production

Which weed control approach relies on rotating herbicides with different modes of action?

  1. Mowing only
  2. Integrated weed management Correct answer.
  3. Continuous use of a single herbicide
  4. Flood irrigation

Explanation

Integrated weed management combines cultural, mechanical, biological and chemical tactics, including rotating herbicide modes of action. This diversity reduces selection pressure and slows the development of resistance.

Question 33Agricultural Production

Which soil property is measured by a pH test?

  1. Acidity or alkalinity of the soil solution Correct answer.
  2. Available phosphorus concentration
  3. Soil bulk density
  4. Microbial biomass carbon

Explanation

Soil pH measures the concentration of hydrogen ions in the soil solution, indicating acidity or alkalinity on a logarithmic scale. It influences nutrient availability and microbial activity.

Question 34Agricultural Production

A grower applies 250 kg of a fertiliser containing 18% nitrogen per hectare. How much nitrogen is applied per hectare?

  1. 72 kg
  2. 250 kg
  3. 45 kg Correct answer.
  4. 18 kg

Explanation

The nitrogen applied equals the product of the application rate and the nutrient concentration: 250 kg multiplied by 0.18 gives 45 kg of nitrogen per hectare.

Question 35Agricultural Production

Which grazing management principle best describes the purpose of rotational grazing?

  1. Allowing pasture to recover between grazing periods Correct answer.
  2. Increasing stocking rate without regard to pasture growth
  3. Grazing the same paddock continuously year-round
  4. Removing all animals during the growing season

Explanation

Rotational grazing moves livestock between paddocks so that pastures can rest and regrow. This rest period allows leaf area to recover, roots to replenish and plants to maintain vigour.

Question 36Agricultural Production

A crop is showing poor establishment on a compacted paddock. Which management action is most likely to improve root growth?

  1. Applying a foliar fungicide
  2. Deep ripping to break the compacted layer Correct answer.
  3. Irrigating more frequently
  4. Increasing seeding rate

Explanation

Compacted layers restrict root penetration and water infiltration. Deep ripping mechanically fractures these layers, allowing roots to reach deeper soil moisture and nutrients.

Question 37Agricultural Production

Which factor most directly determines the digestibility of a pasture for grazing livestock?

  1. The colour of the leaves
  2. The height of the sward
  3. The number of species present
  4. The proportion of fibre and lignin in the plant Correct answer.

Explanation

Digestibility is largely determined by the plant's fibre and lignin content, which increases as plants mature. Younger, leafy pasture has lower fibre and higher digestibility than stemmy, mature pasture.

Question 38Agricultural Production

Which statement best describes the purpose of a crop rotation that includes a legume?

  1. To eliminate the need for any pest management
  2. To increase herbicide use
  3. To reduce soil organic matter
  4. To add nitrogen to the soil through symbiotic fixation Correct answer.

Explanation

Legumes form symbiotic relationships with rhizobia bacteria, converting atmospheric nitrogen into plant-available forms. This contributes nitrogen to the soil, benefiting subsequent crops in the rotation.

Question 39Agricultural Production

A producer notices that a herd is gaining weight more slowly than expected despite adequate pasture. Which factor should be investigated first?

  1. The age of the fence
  2. The size of the paddock
  3. The presence of internal parasites or disease Correct answer.
  4. The colour of the pasture

Explanation

Internal parasites and disease can reduce feed conversion efficiency even when pasture is available. Investigating animal health is a logical first step before examining other management factors.

Question 40Agricultural Production

Which irrigation strategy is most water-efficient for a crop with a shallow root system?

  1. Flooding the paddock once per season
  2. Irrigating only at night regardless of crop demand
  3. Infrequent large applications saturating the profile
  4. Frequent small applications matching crop water use Correct answer.

Explanation

Frequent small applications that match crop water use keep moisture in the shallow root zone. This reduces deep drainage losses below the roots and improves water use efficiency.

Question 41Agricultural Production

Which statement best describes the role of soil organic matter in nutrient supply?

  1. It only supplies phosphorus
  2. It has no effect on nutrient availability
  3. It permanently locks nutrients so plants cannot access them
  4. It acts as a reservoir that releases nutrients through mineralisation Correct answer.

Explanation

Soil organic matter stores nutrients in organic forms and releases them gradually through microbial mineralisation. This provides a slow, steady supply that complements applied fertilisers.

Question 42Agricultural Production

A farmer needs to compare the profitability of two enterprises. Which calculation is most useful?

  1. Number of employees
  2. Average rainfall
  3. Gross margin per hectare Correct answer.
  4. Total farm revenue

Explanation

A gross margin subtracts variable costs from gross income for a specific enterprise, allowing a fair comparison per unit area. It highlights which enterprise returns more per hectare after direct costs.

Question 43Agricultural Production

Which practice best reduces the risk of soil erosion on a steep cultivated slope?

  1. Contour cultivation Correct answer.
  2. Removing all vegetation
  3. Cultivating up and down the slope
  4. Increasing tillage depth

Explanation

Contour cultivation runs tillage and crop rows across the slope, slowing water flow and reducing erosion. It traps sediment and water in furrows rather than allowing it to run downhill.

Question 44Agricultural Production

Which factor is most important when selecting a pasture species for a paddock with waterlogged winter soils?

  1. Drought tolerance
  2. Seed colour
  3. Tolerance to waterlogging Correct answer.
  4. Maximum height

Explanation

Species selection should match the limiting environmental factor, which in this case is waterlogging. Species with tolerance to prolonged saturation will persist better than those that cannot survive waterlogged roots.

Question 45Agricultural Production

Which statement correctly describes the relationship between stocking rate and pasture sustainability?

  1. Exceeding carrying capacity leads to pasture decline over time Correct answer.
  2. Stocking rate has no effect on pasture persistence
  3. Higher stocking rates always improve pasture health
  4. Lower stocking rates always reduce profitability

Explanation

When stocking rate exceeds carrying capacity, pasture is grazed faster than it can regrow, depleting root reserves and reducing persistence. Sustainable grazing keeps stocking rate within the pasture's capacity.

Question 46Agricultural Production

A grower wants to determine the most economic rate of nitrogen for a wheat crop. Which approach is most appropriate?

  1. Applying the maximum rate recommended on the bag
  2. Ignoring grain prices
  3. Applying nitrogen only at sowing
  4. Comparing the marginal cost of nitrogen with the marginal value of extra yield Correct answer.

Explanation

The economic optimum occurs where the marginal cost of the last unit of nitrogen equals the marginal value of the additional yield it produces. This requires comparing input costs with grain prices.

Question 47Agricultural Production

In a controlled traffic farming system, why are wheel tracks kept in the same position each season?

  1. To eliminate the need for fertiliser
  2. To increase the number of wheeled passes
  3. To confine compaction to permanent traffic lanes Correct answer.
  4. To reduce crop yield in the lanes

Explanation

Controlled traffic farming confines all machinery traffic to permanent lanes, so compaction is limited to those zones. The majority of the paddock remains uncompacted, improving infiltration and root growth.

Question 48Agricultural Production

Which explanation best accounts for the build-up of herbicide-resistant weeds in a cropping system?

  1. Regular monitoring of weed populations
  2. Increased crop rotation diversity
  3. Use of integrated weed management
  4. Repeated selection pressure from the same herbicide group Correct answer.

Explanation

Herbicide resistance develops when the same herbicide group is used repeatedly, selecting for individuals with resistance genes. These survivors reproduce and increase in frequency in the population.

Question 49Agricultural Production

A producer is planning a grazing system for a paddock with a mix of perennial grasses and annual legumes. Which management approach best maintains both components?

  1. Rotational grazing with rest periods timed to legume seed set Correct answer.
  2. Grazing only during the legume flowering period
  3. Removing all legumes to simplify management
  4. Continuous heavy grazing throughout the year

Explanation

Annual legumes need to set seed to regenerate in the following season, while perennial grasses need rest to maintain root reserves. Rotational grazing with rest periods timed to allow legume seed set balances both requirements.

Question 50Agricultural Production

Which factor most strongly limits the reliability of a single soil test result for making fertiliser decisions?

  1. The brand of testing laboratory
  2. Spatial variability within the paddock Correct answer.
  3. The time of day the sample was taken
  4. The colour of the soil sample bag

Explanation

Soil properties vary spatially across a paddock, so a single sample may not represent the whole area. Composite or grid sampling improves reliability by accounting for this variability.