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NZ Scholarship Agricultural and Horticultural Science study materials
NZ Scholarship Agricultural and Horticultural Science study resources

NZ Scholarship Agricultural and Horticultural Science practice questions

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Question 1Agricultural and Horticultural Science

A dairy farmer wants to estimate the metabolisable energy (ME) content of a pasture sample from its digestibility. Which relationship best describes how ME is conventionally estimated from digestible organic matter in pasture?

  1. ME (MJ/kg DM) ≈ 1.6 × digestible organic matter (%)
  2. ME (MJ/kg DM) ≈ 0.16 × digestible organic matter (%) Correct answer.
  3. ME (MJ/kg DM) ≈ digestible organic matter (%) ÷ 0.16
  4. ME (MJ/kg DM) ≈ 0.016 × digestible organic matter (%)

Explanation

For temperate pasture, metabolisable energy is commonly estimated as approximately 0.16 MJ per kilogram of dry matter for each percentage unit of digestible organic matter. This gives realistic values around 9–11 MJ ME/kg DM for high-quality pasture at 60–70% digestibility. The relationship is an approximation used in feed budgeting rather than a precise thermodynamic constant.

Question 2Agricultural and Horticultural Science

In New Zealand pastoral systems, which pasture species is a C4 grass that grows most productively during summer and is often used to fill the summer–autumn feed gap?

  1. Cocksfoot
  2. Kikuyu Correct answer.
  3. White clover
  4. Perennial ryegrass

Explanation

Kikuyu is a subtropical C4 grass that responds strongly to warm summer temperatures and can out-produce C3 pasture species such as ryegrass in northern regions during summer. C4 photosynthesis gives it a temperature advantage in hot conditions. White clover is a legume, not a grass, and cocksfoot is a C3 grass.

Question 3Agricultural and Horticultural Science

A farmer applies nitrogen fertiliser to boost winter pasture growth. Which mechanism best explains why nitrogen application increases dry matter production in a grass sward?

  1. It increases the water-holding capacity of the soil profile
  2. It stimulates nitrogen fixation by clover in the sward
  3. It increases the rate of leaf appearance and tiller density by supporting protein synthesis and canopy expansion Correct answer.
  4. It raises soil pH, which directly increases phosphorus availability

Explanation

Nitrogen supports the synthesis of proteins and chlorophyll, driving leaf expansion, tillering and canopy development, which raises intercepted light and growth rate. Applications also commonly increase the rate of leaf appearance in grasses. The other options describe effects that are not the primary mechanism by which nitrogen fertiliser boosts grass dry matter.

Question 4Agricultural and Horticultural Science

Which soil condition most directly limits pasture root growth and nutrient uptake on a compacted, poorly drained paddock?

  1. Low soil phosphorus
  2. Low soil temperature
  3. Reduced oxygen supply to roots Correct answer.
  4. High soil organic matter

Explanation

Compaction and poor drainage reduce air-filled porosity, so roots experience hypoxia, which restricts respiration and nutrient uptake and limits root extension. This is the direct physical effect of compaction and waterlogging. Low phosphorus or low temperature may reduce growth but are not the direct consequence of compaction and poor drainage.

Question 5Agricultural and Horticultural Science

In a breeding programme, a trait with high heritability and easily measured phenotype is best managed by which selection strategy?

  1. Reciprocal recurrent selection across breeds
  2. Mass selection based on individual phenotype Correct answer.
  3. Progeny testing of sires before any selection
  4. Marker-assisted selection using only genomic data

Explanation

When a trait is highly heritable and cheaply measured, selection on individual phenotype (mass selection) gives rapid genetic gain because the phenotype closely reflects breeding value. Progeny testing is costly and slow, and is used where heritability is low or the trait is sex-limited. Genomic or cross-breed schemes are unnecessary when the phenotype is reliable.

Question 6Agricultural and Horticultural Science

A horticultural grower wants to reduce post-harvest water loss from leafy vegetables during cool storage. Which practice most directly reduces transpiration and wilting?

  1. Maintaining high relative humidity around the produce Correct answer.
  2. Increasing air velocity through the cool store
  3. Storing produce at higher temperature to speed air movement
  4. Removing the outer leaves before storage

Explanation

The rate of water loss from produce depends largely on the vapour pressure deficit between the tissue and the surrounding air. High relative humidity reduces this deficit and therefore reduces transpiration and wilting. Higher temperature or faster air movement increases the deficit and accelerates water loss.

Question 7Agricultural and Horticultural Science

Which statement best explains why crop rotation reduces the build-up of soil-borne pathogens in a vegetable production system?

  1. Rotation eliminates all soil organisms, including pathogens
  2. Rotation increases the use of nitrogen fertiliser, which suppresses pathogens
  3. Rotating crops always increases soil pH to a level that kills pathogens
  4. Different crop species support different pathogen populations, so the host is removed and pathogen inoculum declines Correct answer.

Explanation

Soil-borne pathogens are often host-specific, so growing a non-host crop starves the pathogen of its host and reduces inoculum build-up over successive seasons. Rotation also diversifies the soil microbial community and can improve soil structure. Rotation does not sterilise soil or act through a simple pH or fertiliser mechanism.

Question 8Agricultural and Horticultural Science

In an apple orchard, biennial bearing is a problem. Which management practice most reliably reduces the tendency for heavy and light crops to alternate between years?

  1. Pruning heavily in the light-crop year
  2. Removing all flowers every second year
  3. Applying more nitrogen in the light-crop year
  4. Thinning flowers or fruitlets in the heavy-crop year Correct answer.

Explanation

Biennial bearing is driven by the heavy crop suppressing flower initiation for the following season. Thinning flowers or fruitlets in the heavy year reduces the crop load and allows return bloom, smoothing the cycle. Removing all flowers or relying on nitrogen and pruning does not address the crop-load mechanism.

Question 9Agricultural and Horticultural Science

A greenhouse tomato crop shows interveinal yellowing on older leaves with green veins and poor fruit set. Which nutrient deficiency is most consistent with these symptoms?

  1. Magnesium Correct answer.
  2. Boron
  3. Iron
  4. Calcium

Explanation

Magnesium is mobile in the plant, so deficiency appears first on older leaves as interveinal chlorosis while veins remain green, because magnesium is remobilised to younger tissue. Poor fruit set can follow from reduced photosynthesis. Iron deficiency also causes interveinal chlorosis but typically appears on young leaves because iron is immobile.

Question 10Agricultural and Horticultural Science

Which grazing management principle best explains why rotational grazing can increase pasture dry matter utilisation compared with set stocking?

  1. It allows animals to select a diet of higher digestibility from a rested sward Correct answer.
  2. It removes the need for nitrogen fertiliser
  3. It prevents any pasture from reaching reproductive growth
  4. It increases the total number of animals carried on the farm

Explanation

Rotational grazing controls grazing duration and allows swards to recover leaf area between grazings, improving regrowth and enabling animals to graze leafy, higher-digestibility pasture. Better utilisation refers to the proportion of grown pasture consumed. It does not automatically raise stocking rate, prevent all reproductive growth, or remove fertiliser needs.

Question 11Agricultural and Horticultural Science

A farmer is considering using a long-acting anthelmintic drench in a sheep flock. Which practice best slows the development of drench resistance?

  1. Drenching animals immediately after moving them to clean pasture
  2. Leaving a proportion of animals untreated to maintain a refugia population of susceptible worms Correct answer.
  3. Using the same drench family every season for consistency
  4. Drenching all animals frequently to keep worm burdens low

Explanation

Refugia are the susceptible worms in untreated animals and on pasture that are not exposed to the drench. Maintaining refugia dilutes resistant survivors and slows the selection for resistance. Frequent whole-flock drenching, repeated use of one family, and drenching onto clean pasture all increase selection pressure.

Question 12Agricultural and Horticultural Science

In a dairy herd, which factor most directly determines the amount of pasture dry matter an animal can consume per day?

  1. The breed of the neighbouring herd
  2. The colour of the pasture sward
  3. The animal's liveweight and the digestibility of the pasture Correct answer.
  4. The number of paddocks on the farm

Explanation

Intake is driven mainly by the animal's metabolic demand (closely related to liveweight and production level) and by pasture digestibility, which controls passage rate and the physical limit to intake. Higher digestibility generally allows greater intake. Sward colour, paddock number and neighbouring breed do not directly set daily intake.

Question 13Agricultural and Horticultural Science

Which process in the rumen allows ruminants to utilise fibrous plant material that monogastric animals cannot digest efficiently?

  1. Absorption of intact fibre through the rumen wall
  2. Mechanical grinding of fibre by the teeth alone
  3. Enzymatic breakdown of cellulose in the stomach
  4. Microbial fermentation of fibre by rumen bacteria and protozoa Correct answer.

Explanation

Rumen microbes produce cellulolytic and hemicellulolytic enzymes that ferment fibre into volatile fatty acids, which the animal absorbs as an energy source. This symbiotic fermentation is the key reason ruminants exploit fibrous pasture. Monogastric animals lack this microbial population and enzyme capacity in a pre-gastric fermentation chamber.

Question 14Agricultural and Horticultural Science

A grower uses integrated pest management (IPM) in a glasshouse. Which action is most consistent with an IPM approach?

  1. Increasing pesticide rates after every pest sighting
  2. Monitoring pest populations and releasing a biological control agent only when thresholds are reached Correct answer.
  3. Applying a broad-spectrum insecticide on a fixed calendar regardless of pest numbers
  4. Removing all beneficial insects to simplify pest control

Explanation

IPM combines monitoring, thresholds and multiple control tactics, using biological control where it is effective and reserving chemicals for when thresholds are exceeded. Calendar spraying and removing beneficial insects are the opposite of IPM. Threshold-based decisions avoid unnecessary pesticide use and slow resistance development.

Question 15Agricultural and Horticultural Science

A soil test reports an Olsen P value of 12 on a dairy farm where the target for the enterprise is 25–30. Which interpretation and action is most appropriate?

  1. The soil is below target, so phosphorus should be applied to build soil fertility Correct answer.
  2. The soil is above target, so phosphorus application can be stopped
  3. Olsen P is irrelevant to pasture production and should be ignored
  4. The soil is at target, so no change is needed

Explanation

Olsen P is a measure of plant-available phosphorus, and a value well below the target range indicates a need to build soil fertility with phosphorus inputs. Applying phosphorus to raise Olsen P towards the target supports pasture growth. Stopping phosphorus would further deplete available reserves.

Question 16Agricultural and Horticultural Science

Which management practice most effectively reduces nitrate leaching from a grazed pasture system on a free-draining soil?

  1. Applying nitrogen fertiliser in late autumn when plant uptake is low
  2. Avoiding grazing and fertiliser inputs during periods of high drainage and low plant demand Correct answer.
  3. Cultivating the paddock to increase soil aeration
  4. Increasing stocking rate to cycle nitrogen faster

Explanation

Nitrate leaching depends on the amount of nitrate in the soil and the volume of drainage. Avoiding grazing and fertiliser applications when plant uptake is low and drainage is high reduces the pool of nitrate available to leach. Applying nitrogen in late autumn or increasing stocking rate increases the risk.

Question 17Agricultural and Horticultural Science

In a plant breeding programme, which method is most appropriate for producing a new cultivar that combines desirable traits from two distinct parent lines?

  1. Clonal propagation of one parent
  2. Hybridisation followed by selection among progeny Correct answer.
  3. Tissue culture of a single elite plant
  4. Mutation breeding using gamma irradiation alone

Explanation

Hybridisation crosses the two parents to recombine their traits, and selection among the segregating progeny identifies individuals that combine the desired characteristics. Clonal propagation and tissue culture multiply an existing genotype without combining traits. Mutation breeding introduces random variation rather than combining specific parental traits.

Question 18Agricultural and Horticultural Science

A vineyard experiences a late frost event during budburst. Which factor most influences the extent of damage to the developing shoots?

  1. The colour of the grape variety
  2. The number of vines per hectare
  3. The stage of bud development at the time of the frost Correct answer.
  4. The soil type of the vineyard block

Explanation

Susceptibility to frost damage increases as buds develop, with newly burst shoots being more sensitive than dormant buds. The temperature reached and its duration also matter, but the developmental stage is the key determinant of tissue sensitivity. Soil type and vine density influence site factors but not the intrinsic sensitivity of the bud stage.

Question 19Agricultural and Horticultural Science

Which statement best describes the role of a shelterbelt in a horticultural enterprise?

  1. It reduces wind speed, thereby reducing evapotranspiration and mechanical damage to crops Correct answer.
  2. It increases wind speed to improve pollination
  3. It increases soil temperature to extend the growing season
  4. It eliminates the need for irrigation

Explanation

Shelterbelts reduce wind speed in their lee, which lowers evapotranspiration, reduces mechanical damage to foliage and fruit, and can improve pollination and fruit quality. They do not eliminate the need for irrigation or substantially raise soil temperature. Increased wind speed would be counterproductive.

Question 20Agricultural and Horticultural Science

A farmer is deciding whether to conserve surplus spring pasture as silage. Which factor most strongly affects the feeding value of the resulting silage?

  1. The colour of the silage wrap
  2. The stage of maturity of the pasture at cutting Correct answer.
  3. The number of bales produced
  4. The size of the silage stack

Explanation

The feeding value of silage depends largely on the digestibility and water-soluble carbohydrate content of the pasture at cutting, which decline as the sward matures. Cutting at the right stage preserves energy and protein. Wrap colour, stack size and bale number affect preservation and logistics but not the intrinsic feed value of the forage.

Question 21Agricultural and Horticultural Science

Which factor is most likely to cause a high somatic cell count in a dairy herd?

  1. Grazing pasture with a high clover content
  2. Using a rotational grazing system
  3. Milking machine malfunction and poor teat hygiene Correct answer.
  4. Feeding a diet high in pasture

Explanation

Somatic cell count is an indicator of udder inflammation, most often caused by intramammary infection. Milking machine faults and poor teat hygiene increase bacterial exposure and teat damage, raising infection risk and cell counts. Diet and grazing system are not direct causes of elevated somatic cell count.

Question 22Agricultural and Horticultural Science

In a crop rotation, a legume such as clover is included. Which benefit most directly explains its inclusion?

  1. It increases soil phosphorus through weathering of rock phosphate
  2. It increases soil bulk density to improve drainage
  3. It fixes atmospheric nitrogen through rhizobia, adding nitrogen to the system Correct answer.
  4. It eliminates all weeds from the following crop

Explanation

Legumes form symbiotic associations with rhizobia that fix atmospheric nitrogen, which can be transferred to the soil and following crops through residues and grazing returns. This reduces reliance on nitrogen fertiliser. Legumes do not add phosphorus by weathering rock phosphate or eliminate weeds, and higher bulk density would impair drainage.

Question 23Agricultural and Horticultural Science

A researcher wants to compare the effect of three fertiliser treatments on pasture yield. Which experimental design feature is most important to ensure valid comparison?

  1. Random allocation of treatments with replication across the site Correct answer.
  2. Using different pasture species in each treatment
  3. Applying all treatments to one small plot
  4. Measuring yield only once at the end of the season

Explanation

Randomisation and replication distribute unavoidable site variation across treatments and provide a basis for estimating experimental error, which is essential for valid comparison. A single plot cannot separate treatment effects from site effects, and using different species confounds the treatment effect.

Question 24Agricultural and Horticultural Science

A farmer observes that a pasture sward has become dominated by low-growing weeds and bare ground after several years of set stocking. Which explanation best accounts for this change?

  1. Nitrogen fixation by clover directly killed the grasses
  2. The soil became too fertile for any pasture species to grow
  3. The pasture species mutated into weeds over time
  4. Selective grazing and trampling reduced the vigour of desirable pasture species, allowing weeds to establish Correct answer.

Explanation

Continuous set stocking allows selective grazing of palatable species and causes trampling damage, reducing the vigour and competitive ability of desirable pasture plants. This creates gaps that weeds exploit. Pasture plants do not mutate into weeds, and clover nitrogen fixation or high fertility does not directly kill grasses.

Question 25Agricultural and Horticultural Science

A horticultural export business is assessing fruit quality for a long sea freight. Which combination of measures best predicts storage life?

  1. Dry matter content and firmness at harvest Correct answer.
  2. Orchard altitude and row orientation
  3. Fruit colour and size at harvest
  4. Number of fruit per carton and carton colour

Explanation

Dry matter content reflects the accumulation of carbohydrates that support post-harvest quality, and firmness indicates tissue condition and ripening stage; both are established predictors of storage life in crops such as kiwifruit. Colour and size are less directly related to storage potential. Carton attributes and orchard layout do not predict fruit storage life.

Question 26Agricultural and Horticultural Science

In a pastoral system, which soil property is most directly improved by maintaining a high earthworm population?

  1. Soil potassium exchange selectivity
  2. Soil bulk density and macropore formation Correct answer.
  3. Soil pH buffering against liming
  4. Soil phosphorus retention capacity

Explanation

Earthworms burrow through soil and ingest organic matter, creating macropores and casts that lower bulk density and improve aeration and drainage. These physical changes dominate over any direct effect on phosphorus retention, pH buffering or potassium selectivity.

Question 27Agricultural and Horticultural Science

A grower applies lime to a pastoral soil with a measured pH of 5.4 and a target pH of 6.0. Which outcome is the most direct expected benefit?

  1. Reduced clover nodulation and nitrogen fixation
  2. Increased leaching of sulphate below the root zone
  3. Increased soil bulk density in the topsoil
  4. Increased availability of molybdenum and reduced aluminium toxicity Correct answer.

Explanation

Raising pH toward 6.0 reduces the solubility of toxic aluminium and increases the availability of molybdenum, both of which favour legume growth and pasture production. Liming does not increase sulphate leaching, suppress clover nodulation or increase bulk density.

Question 28Agricultural and Horticultural Science

Which statement best describes the role of the abomasum in the ruminant digestive system?

  1. It is the true stomach where acid and enzymes begin protein digestion Correct answer.
  2. It is the site where water and minerals are absorbed from the digesta
  3. It is a fermentation chamber where microbes break down cellulose
  4. It is a storage organ that regulates the flow of ingesta to the reticulum

Explanation

The abomasum is the glandular stomach, secreting hydrochloric acid and enzymes such as rennin and pepsin to begin protein digestion. Fermentation occurs in the rumen and reticulum, while water absorption occurs mainly in the large intestine.

Question 29Agricultural and Horticultural Science

A horticultural crop is grown under a plasticulture system with drip irrigation. Which advantage most directly justifies the capital cost of the plastic mulch?

  1. Increased soil pH through plastic degradation
  2. Reduced need for pollination in the crop
  3. Elimination of the need for fertiliser application
  4. Improved soil moisture retention and weed suppression Correct answer.

Explanation

Plastic mulch reduces evaporation from the soil surface and blocks light, suppressing weed germination, which together improve water use efficiency and reduce weed competition. It does not raise pH, remove pollination requirements or eliminate fertiliser needs.

Question 30Agricultural and Horticultural Science

Which factor most directly determines the storage life of a kiwifruit crop held in a coolstore?

  1. The soil type in which the vines were established
  2. Fruit dry matter at harvest and pulp temperature management Correct answer.
  3. The number of canes retained at winter pruning
  4. The cultivar's flower colour at anthesis

Explanation

Storage life of kiwifruit is closely linked to fruit dry matter at harvest, which reflects carbohydrate accumulation, and to rapid cooling and consistent pulp temperature management after harvest. Flower colour, soil type and cane number influence growth but not storage life as directly.

Question 31Agricultural and Horticultural Science

Which practice best reduces the risk of drench resistance developing in a sheep flock?

  1. Increasing dose rates above label recommendations to ensure kill
  2. Using effective combinations and leaving a proportion of the flock untreated as refugia Correct answer.
  3. Treating all animals frequently with a single long-acting product
  4. Rotating drench families within a single season without efficacy testing

Explanation

Refugia, achieved by leaving a proportion of animals untreated, maintains a population of susceptible parasites that dilute resistant genotypes. Using effective combinations and testing efficacy further slows selection for resistance.

Question 32Agricultural and Horticultural Science

Which management decision best illustrates the principle of matching pasture supply to animal demand in a seasonal calving system?

  1. Purchasing supplementary feed only when pasture is abundant
  2. Running a constant stocking rate regardless of season
  3. Applying nitrogen fertiliser continuously throughout the year
  4. Setting stocking rate and calving date to align peak lactation with peak pasture growth Correct answer.

Explanation

Matching peak lactation demand to peak pasture growth by aligning calving date and stocking rate reduces reliance on supplements and improves feed conversion. Continuous nitrogen use or constant stocking does not achieve this alignment.

Question 33Agricultural and Horticultural Science

Which statement best explains why shelterbelts can increase the yield of a horticultural crop on an exposed site?

  1. They raise soil pH through leaf litter decomposition
  2. They eliminate the need for irrigation by increasing rainfall
  3. They increase soil temperature by blocking cold air drainage
  4. They reduce wind speed, lowering evapotranspiration and mechanical damage to foliage Correct answer.

Explanation

Shelterbelts reduce wind speed, which lowers evapotranspiration and reduces mechanical damage, improving the crop microclimate. They do not increase rainfall, raise pH or reliably increase soil temperature.

Question 34Agricultural and Horticultural Science

A dairy farmer is deciding whether to apply nitrogen fertiliser to a pasture in late autumn on a free-draining soil. Which consideration is most relevant to minimising nitrate leaching?

  1. Applying when soil temperature is below 5 degrees Celsius
  2. Applying at the highest label rate to maximise pasture cover
  3. Applying immediately before forecast heavy rainfall to aid incorporation
  4. Applying when pasture growth is active and demand is high, avoiding heavy rain forecasts Correct answer.

Explanation

Nitrogen should be applied when pasture is actively growing and can take up the nitrogen, and application should be avoided before heavy rain that would move nitrate below the root zone. High rates and cold soils increase the risk of loss.

Question 35Agricultural and Horticultural Science

A glasshouse tomato crop shows blossom-end rot on developing fruit. Which management response is most appropriate?

  1. Reduce calcium in the nutrient solution to avoid antagonism
  2. Increase the electrical conductivity of the solution sharply to concentrate nutrients
  3. Stabilise calcium supply by managing irrigation and vapour pressure deficit Correct answer.
  4. Increase nitrogen application to boost vegetative growth

Explanation

Blossom-end rot is associated with localised calcium deficiency in the fruit, often driven by irregular water supply and high vapour pressure deficit rather than low soil calcium. Stabilising irrigation and humidity improves calcium transport to the fruit.

Question 36Agricultural and Horticultural Science

In an apple orchard, which practice best reduces the risk of resistance in apple scab to a single-site fungicide?

  1. Applying the single-site fungicide alone throughout the season
  2. Tank-mixing or alternating with a multi-site protectant and limiting the number of applications per season Correct answer.
  3. Applying the single-site fungicide more frequently at a lower rate
  4. Using the same single-site fungicide every season without rotation

Explanation

Resistance management relies on reducing selection pressure by limiting applications of single-site fungicides and combining them with multi-site protectants that have multiple modes of action. Frequent or exclusive use of one single-site product accelerates resistance.

Question 37Agricultural and Horticultural Science

A pastoral soil test shows a potassium level well below the target range for a high-producing dairy farm. Which interpretation is most appropriate?

  1. Potassium is adequate because clovers fix nitrogen
  2. Potassium may limit pasture growth and clover persistence, so a maintenance-plus corrective application is warranted Correct answer.
  3. Potassium should be reduced to avoid luxury uptake
  4. Potassium levels are irrelevant to pasture yield

Explanation

Potassium is essential for osmoregulation, enzyme activation and clover persistence, and levels below target can limit growth. A corrective and maintenance application based on soil test results is appropriate.

Question 38Agricultural and Horticultural Science

A grower wants to reduce the incidence of clubroot in a brassica crop. Which management approach is most effective?

  1. Increasing soil moisture and applying fresh manure
  2. Maintaining soil pH near neutral and using long rotations with non-host crops Correct answer.
  3. Applying nitrogen fertiliser at high rates
  4. Growing brassicas continuously to build soil biology

Explanation

Clubroot is favoured by acidic soils, so maintaining pH near neutral reduces disease severity, and long rotations with non-host crops reduce inoculum build-up. Continuous brassica cropping increases pathogen load.

Question 39Agricultural and Horticultural Science

In a plant breeding programme, which approach is most suitable for rapidly producing a homozygous line from a heterozygous parent?

  1. Doubled haploid production via anther culture Correct answer.
  2. Recurrent mass selection over many generations
  3. Backcrossing to the recurrent parent without selection
  4. Clonal propagation by cuttings

Explanation

Doubled haploid production generates fully homozygous lines in a single generation, shortening the breeding cycle. Mass selection and backcrossing require multiple generations, and cuttings produce clones rather than homozygous lines.

Question 40Agricultural and Horticultural Science

Which factor best explains why a pasture sward becomes dominated by low-growing weeds and bare ground after several years of set stocking?

  1. Reduced soil compaction improves root penetration
  2. Higher legume content increases nitrogen fixation
  3. Selective grazing and trampling reduce desirable species vigour and allow weed ingress Correct answer.
  4. Increased earthworm activity improves soil structure

Explanation

Set stocking allows selective grazing of palatable species and trampling damage, reducing the vigour of desirable pasture plants and creating gaps for weeds. Rotational grazing and spelling allow recovery and maintain sward density.

Question 41Agricultural and Horticultural Science

A horticultural export business is preparing fruit for a long sea freight. Which combination of measures best preserves quality?

  1. Increasing respiration by storing at higher temperatures to maintain firmness
  2. Applying ethylene to accelerate ripening before shipment
  3. Rapid cooling after harvest, controlled atmosphere storage and careful handling to avoid bruising Correct answer.
  4. Delaying cooling to allow field heat to dissipate naturally and storing at ambient temperature

Explanation

Rapid cooling removes field heat and slows respiration, controlled atmosphere reduces oxygen and raises carbon dioxide to slow ripening, and careful handling limits bruising and decay. Delayed cooling and higher temperatures accelerate deterioration.

Question 42Agricultural and Horticultural Science

A researcher wants to compare three fertiliser treatments on pasture yield across a paddock with a fertility gradient. Which design feature best controls the gradient effect?

  1. A single large plot per treatment
  2. Randomised complete block design with blocks aligned across the gradient Correct answer.
  3. Completely random allocation of plots across the paddock
  4. Replicated plots all located at one end of the paddock

Explanation

Blocking groups plots of similar fertility together, so variation due to the gradient is removed from the treatment comparison. Randomisation within blocks then ensures unbiased allocation.

Question 43Agricultural and Horticultural Science

Which statement best explains why a legume such as white clover is included in a pasture mix for a sheep farm?

  1. It prevents the establishment of grasses
  2. It fixes atmospheric nitrogen through rhizobia, increasing nitrogen supply to the sward Correct answer.
  3. It increases the carbon to nitrogen ratio of the pasture
  4. It reduces the feed value of the pasture

Explanation

Rhizobia in root nodules fix atmospheric nitrogen, which becomes available to associated grasses through cycling of clover litter and roots. This reduces reliance on nitrogen fertiliser and improves feed quality.

Question 44Agricultural and Horticultural Science

A dairy herd has an elevated bulk milk somatic cell count. Which management factor is most likely to be responsible?

  1. Adequate teat spraying after milking
  2. High pasture allowance in early lactation
  3. Use of a balanced mineral supplement
  4. Poor teat hygiene and milking machine function leading to intramammary infection Correct answer.

Explanation

Elevated somatic cell counts usually reflect intramammary infection (mastitis), often linked to poor teat hygiene, inadequate teat spraying and faulty milking machines. Good hygiene and machine maintenance reduce the risk.

Question 45Agricultural and Horticultural Science

Which factor most strongly influences the feeding value of silage made from surplus spring pasture?

  1. The breed of the animals that will be fed
  2. The stage of maturity at cutting and the wilting and fermentation conditions Correct answer.
  3. The colour of the plastic wrap used to seal the stack
  4. The number of paddocks on the farm

Explanation

Feeding value depends mainly on the maturity of the pasture at cutting, which determines fibre and digestibility, and on wilting and fermentation conditions that affect preservation. Wrap colour or farm layout has little direct effect.

Question 46Agricultural and Horticultural Science

A grower observes that a crop grown in a glasshouse has become tall, pale and weak-stemmed under a high-nitrogen regime. Which interpretation and response is most appropriate?

  1. The crop needs more nitrogen to strengthen stems
  2. Excess nitrogen has caused lush growth, so nitrogen should be reduced and light and calcium managed Correct answer.
  3. The symptoms indicate potassium deficiency
  4. The crop should be shaded to reduce elongation

Explanation

Excess nitrogen promotes vegetative elongation, pale leaves and weak stems, increasing susceptibility to disease and lodging. Reducing nitrogen and managing light and calcium improves plant balance.

Question 47Agricultural and Horticultural Science

In a pastoral grazing system, which factor most directly determines the pasture dry matter intake of a grazing animal?

  1. The colour of the pasture sward
  2. The number of paddocks on the farm
  3. The breed of the neighbouring herd
  4. The herbage mass available and the grazing residual management Correct answer.

Explanation

Intake is governed by the amount of herbage available and the residual left after grazing, which together determine bite size and grazing time. Paddock number and breed of neighbouring stock do not directly determine intake.

Question 48Agricultural and Horticultural Science

A vineyard experiences a late frost during budburst. Which factor most strongly determines the extent of damage to developing shoots?

  1. The soil pH of the vineyard
  2. The cultivar's berry colour
  3. The stage of bud development and the minimum temperature reached at the vine Correct answer.
  4. The number of canes retained at pruning

Explanation

Frost damage depends on how advanced the buds are, since more developed shoots are more susceptible, and on the minimum temperature and duration of the frost. Soil pH, cane number and berry colour do not directly determine frost damage.

Question 49Agricultural and Horticultural Science

An orchardist is evaluating biennial bearing in apples. Which management strategy most reliably reduces the tendency for heavy and light crops to alternate?

  1. Applying more nitrogen in light years to boost yield
  2. Pruning less heavily to increase flower bud numbers
  3. Chemical or hand thinning of flowers and fruitlets in heavy years to balance crop load Correct answer.
  4. Removing all fruit in heavy years to reset the cycle

Explanation

Biennial bearing arises because a heavy crop suppresses flower initiation for the following season. Thinning in heavy years reduces competition and allows flower buds to form, balancing the cycle.

Question 50Agricultural and Horticultural Science

In a crop rotation, a legume is included before a cereal. Which benefit most directly explains this inclusion?

  1. The legume increases the carbon to nitrogen ratio of residues
  2. The legume reduces the cereal's water requirement
  3. The legume increases soil pH for the cereal
  4. Nitrogen fixed by rhizobia becomes available to the following cereal Correct answer.

Explanation

Legumes form symbiotic associations with rhizobia that fix atmospheric nitrogen, much of which becomes available to the following cereal as residues decompose. This reduces the nitrogen fertiliser requirement.