I85PREP
⌘ K
JCE Agriculture study materials
JCE Agriculture study resources

JCE Agriculture practice questions

One question at a time. Build your JCE Agriculture understanding.

First 50 of 200 questions. Each one lists the choices, the correct answer, and an explanation. The checker at the top of this page saves progress in this browser when it is available.

Continue in the practice tool above to load more questions, 50 at a time.

Question 1Crop Production and Husbandry

In a crop rotation plan, which practice best interrupts the life cycle of a soil-borne pathogen that survives on cereal residues?

  1. Ploughing the residue into the seedbed before sowing
  2. Rotating to a non-host break crop for one or more seasons Correct answer.
  3. Planting a cereal crop in the following season
  4. Increasing nitrogen application on the cereal stubble

Explanation

Soil-borne pathogens that survive on specific crop residues decline when a non-host crop is grown, because the pathogen has no living host tissue to colonise and its inoculum declines over the rotation cycle. Rotating to a non-host break crop for one or more seasons is the standard cultural control. Residue management and nutrition may help but do not remove the host bridge.

Question 2Crop Production and Husbandry

Which soil condition most directly limits the availability of phosphorus to a growing crop?

  1. Waterlogged soils with oxygen deficiency
  2. Soils with very low pH below 5.5 Correct answer.
  3. Low soil organic matter only
  4. High soil pH above 7.5

Explanation

In strongly acidic soils, phosphorus is fixed by aluminium and iron compounds into forms the plant cannot absorb, sharply reducing availability. Liming to a suitable pH range is the usual remedy. The other options affect nutrient cycling but are not the primary direct cause of phosphorus lock-up.

Question 3Crop Production and Husbandry

A farmer wants to reduce soil erosion on a sloping field growing row crops. Which practice is most effective?

  1. Removing all crop residue after harvest
  2. Growing a cover crop and using contour cultivation Correct answer.
  3. Planting rows up and down the slope
  4. Deep ploughing before each rainfall season

Explanation

Cover crops protect the soil surface from raindrop impact, and contour cultivation slows runoff along the slope, together reducing erosion substantially. These practices keep soil in place and improve infiltration. The other options either expose soil or channel water downhill.

Question 4Crop Production and Husbandry

Which term describes the process by which legume plants convert atmospheric nitrogen into forms usable by the plant?

  1. Nitrogen mineralisation
  2. Nitrification
  3. Biological nitrogen fixation Correct answer.
  4. Denitrification

Explanation

Biological nitrogen fixation is carried out by rhizobia bacteria in root nodules of legumes, converting atmospheric N2 into ammonia that the plant can use. This is why legumes are valuable in rotations. The other terms describe different steps of the nitrogen cycle.

Question 5Crop Production and Husbandry

In a breeding programme, which technique is used to produce genetically uniform progeny from a homozygous line?

  1. Mutation breeding with chemical mutagens
  2. Hybridisation with a wild relative
  3. Cross-pollination with a heterozygous variety
  4. Self-pollination over successive generations Correct answer.

Explanation

Repeated self-pollination of a homozygous line produces uniform, true-breeding progeny because the parent carries identical alleles at each locus. This is the basis of pure-line development. Cross-pollination and mutagenesis introduce variation and reduce uniformity.

Question 6Crop Production and Husbandry

Which factor is the most important determinant of germination rate in a freshly sown seedbed?

  1. Soil moisture and temperature Correct answer.
  2. Soil colour
  3. Seed size
  4. Depth of the water table

Explanation

Germination requires adequate moisture for imbibition and a suitable temperature for enzyme activity and radicle emergence. These two factors together drive the rate and uniformity of seedling emergence. Soil colour and seed size influence other aspects but not the primary germination conditions.

Question 7Crop Production and Husbandry

Which method of irrigation is generally most efficient in water use for a widely spaced orchard?

  1. Drip irrigation to each tree Correct answer.
  2. Furrow irrigation along the rows
  3. Flood irrigation of the whole field
  4. Sprinkler irrigation over the canopy

Explanation

Drip irrigation delivers water directly to the root zone of each tree, minimising evaporation and deep percolation losses, so it is highly water-efficient for widely spaced crops. It also reduces weed growth between rows. Flood and furrow methods wet large areas and lose more water.

Question 8Crop Production and Husbandry

Which livestock feeding practice best supports rumen microbial function in a high-producing dairy cow?

  1. Feeding only concentrates during lactation
  2. Providing a balanced ration with adequate effective fibre Correct answer.
  3. Feeding a high-starch diet with no forage
  4. Restricting water intake to reduce urine output

Explanation

Rumen microbes need effective fibre to maintain chewing, saliva flow and a stable rumen pH, alongside adequate energy and protein. A balanced ration with fibre supports fermentation and milk yield. Diets lacking fibre or water cause acidosis and reduced production.

Question 9Crop Production and Husbandry

A cereal grower notices yellowing of older leaves first, with stunted growth, in a field that has received adequate nitrogen. Which nutrient deficiency is most likely?

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

Explanation

Magnesium is a mobile nutrient and a central component of chlorophyll, so deficiency appears first on older leaves as interveinal yellowing while veins remain green. The plant redistributes magnesium from older to younger tissue. Iron and calcium are immobile and show symptoms on young leaves.

Question 10Crop Production and Husbandry

In integrated pest management, which action is the first step before deciding to apply a pesticide?

  1. Spray a broad-spectrum insecticide as a precaution
  2. Scout and monitor pest populations against an economic threshold Correct answer.
  3. Apply pesticide only at the end of the season
  4. Increase fertiliser to help plants outgrow the pest

Explanation

IPM requires regular scouting and comparison of pest numbers with an economic threshold before any control is chosen. This avoids unnecessary sprays and preserves natural enemies. Precautionary or delayed spraying ignores monitoring data.

Question 11Crop Production and Husbandry

Which statement correctly describes the effect of a legume in a crop rotation on the following cereal crop?

  1. It increases the need for nitrogen fertiliser on the cereal
  2. It always reduces the following cereal yield by competing for water
  3. It can supply residual nitrogen that benefits the following cereal Correct answer.
  4. It has no effect on soil nitrogen status

Explanation

Legumes fix atmospheric nitrogen and leave nitrogen-rich residues in the soil, which can reduce the fertiliser nitrogen required by the following cereal. The size of the benefit depends on the legume species and how much residue is returned. It does not eliminate nitrogen need entirely.

Question 12Crop Production and Husbandry

A seed lot has a germination percentage of 80% and a purity of 95%. What is the pure live seed percentage?

  1. 85%
  2. 76% Correct answer.
  3. 80%
  4. 95%

Explanation

Pure live seed is calculated by multiplying purity by germination: 0.95 × 0.80 = 0.76, or 76%. This figure is used to adjust sowing rates so that the desired plant population is achieved. It reflects both the proportion of pure seed and the proportion that will germinate.

Question 13Crop Production and Husbandry

Which factor most directly determines the plant population achieved in a cereal field?

  1. Number of tillers per plant only
  2. Colour of the seed coat
  3. Amount of nitrogen applied at sowing
  4. Sowing rate and seed establishment percentage Correct answer.

Explanation

Plant population is set by the number of viable seeds sown per unit area multiplied by the fraction that establish, so sowing rate and establishment percentage are the direct determinants. Tillering and nitrogen affect yield components later but not the initial population.

Question 14Crop Production and Husbandry

In a grazing system, which practice best prevents the build-up of internal parasites in sheep?

  1. Rotating paddocks and avoiding overstocking Correct answer.
  2. Treating all animals with anthelmintic every week
  3. Feeding hay on the ground in the paddock
  4. Grazing the same paddock continuously all season

Explanation

Rotational grazing with rest periods reduces the ingestion of infective larvae because larvae decline on pasture during the rest interval, and avoiding overstocking lowers contamination. Strategic rather than excessive drenching preserves drug efficacy. Continuous grazing and ground feeding increase exposure.

Question 15Crop Production and Husbandry

Which soil structure condition is most favourable for root growth and drainage?

  1. Sodic soil with dispersed clay
  2. Compacted plough pan layer
  3. Massive, structureless clay
  4. Granular, well-aggregated soil Correct answer.

Explanation

Granular, well-aggregated soil has interconnected pore spaces that allow roots to penetrate and water to drain freely while retaining moisture. This structure supports aeration and biological activity. Massive, compacted or sodic soils restrict both root growth and drainage.

Question 16Crop Production and Husbandry

A crop shows wilting during the day even though soil moisture is adequate. Which condition is most likely responsible?

  1. High seed rate
  2. Excess phosphorus in the soil
  3. Low soil pH
  4. Root damage or vascular disease limiting water uptake Correct answer.

Explanation

Wilting despite adequate soil moisture points to a problem in water uptake or transport, such as root rot, nematode damage or a vascular pathogen blocking xylem. The plant cannot move water to the leaves even though it is present in the soil. Nutrient and seed-rate factors do not produce this pattern directly.

Question 17Crop Production and Husbandry

Which practice is most appropriate for controlling weeds in an organic vegetable rotation?

  1. Increasing nitrogen to shade out weeds
  2. Continuous monoculture of the same crop
  3. Mechanical cultivation combined with mulching Correct answer.
  4. Repeated application of a residual herbicide

Explanation

Organic systems rely on cultural and mechanical methods, and combining timely cultivation with mulching suppresses weeds without synthetic herbicides. Mulch also conserves moisture. Monoculture and extra nitrogen do not provide reliable weed control.

Question 18Crop Production and Husbandry

Which characteristic distinguishes a hybrid variety from an open-pollinated variety in terms of seed saving?

  1. Open-pollinated seed cannot be saved
  2. Hybrid seed can be saved and will breed true
  3. Open-pollinated varieties are always higher yielding
  4. Hybrid progeny segregate and lose uniformity if seed is saved Correct answer.

Explanation

Hybrid varieties are produced from controlled crosses of inbred lines, and their progeny segregate in the next generation, losing vigour and uniformity. Open-pollinated varieties can be saved and remain reasonably true if isolated from cross-pollination. This is why growers buy fresh hybrid seed each season.

Question 19Crop Production and Husbandry

In a poultry enterprise, which management factor most directly affects egg production rate?

  1. Photoperiod and lighting programme Correct answer.
  2. Breeding of the rooster
  3. Type of nesting material
  4. Colour of the egg tray

Explanation

Day length controls the hen's reproductive cycle through the hypothalamus-pituitary axis, so a managed lighting programme is a key driver of egg production. Adequate nutrition and health also matter, but photoperiod is the direct management lever. The other factors have little influence on laying rate.

Question 20Crop Production and Husbandry

A field has a history of clubroot in brassicas. Which strategy best reduces disease pressure for a subsequent brassica crop?

  1. Sowing the same susceptible brassica immediately
  2. Applying extra nitrogen fertiliser
  3. Raising soil pH to about 7 and using resistant varieties Correct answer.
  4. Flooding the field for a single day

Explanation

Clubroot is favoured by acidic soils, so raising pH toward neutral with lime reduces disease severity, and resistant varieties further limit infection. Extending the rotation away from brassicas also helps. Short flooding or extra nitrogen does not control the pathogen.

Question 21Crop Production and Husbandry

Which statement about the role of soil organic matter in crop production is most accurate?

  1. It reduces soil biological activity
  2. It always lowers crop yields
  3. It has no effect on nutrient supply
  4. It improves water-holding capacity and cation exchange capacity Correct answer.

Explanation

Soil organic matter increases water-holding capacity, provides cation exchange sites that retain nutrients, and supports soil biological activity. These properties improve fertility and resilience. It also supplies nutrients slowly as it decomposes.

Question 22Crop Production and Husbandry

A grower applies a nitrogen fertiliser just before heavy rain on a sandy soil. What is the most likely outcome?

  1. Nitrate is leached below the root zone Correct answer.
  2. Nitrogen is fully retained in the root zone
  3. Phosphorus availability increases sharply
  4. Nitrogen is converted entirely to organic matter

Explanation

Sandy soils have low water-holding and exchange capacity, and nitrate is highly mobile, so heavy rain soon after application can leach nitrate below the rooting depth. This reduces nitrogen use efficiency and risks groundwater contamination. Splitting applications and timing to crop demand reduces losses.

Question 23Crop Production and Husbandry

Which combination best describes a strategy for managing herbicide resistance in arable weeds?

  1. Increasing the dose of the same herbicide
  2. Rotating herbicide modes of action and integrating cultural controls Correct answer.
  3. Applying herbicide only after resistance appears
  4. Using the same herbicide mode of action every year

Explanation

Resistance management relies on diversifying selection pressure: rotating herbicide modes of action, mixing or sequencing actives, and combining with cultural controls such as rotation, delayed sowing and mechanical weeding. Repeating one mode of action selects resistant biotypes. Reactive or dose-escalation approaches are ineffective.

Question 24Crop Production and Husbandry

In a dairy herd, a ration is balanced for energy and protein but cows show poor rumen function and low milk fat. Which dietary factor is most likely limiting?

  1. Vitamin C content
  2. Effective fibre content Correct answer.
  3. Dietary salt level
  4. Total water supply

Explanation

Low milk fat and poor rumen function on an energy- and protein-balanced ration usually indicate insufficient effective fibre, which lowers chewing and saliva buffering and shifts fermentation toward acid production. Increasing effective fibre restores rumen pH and fat synthesis. Water, vitamin C and salt are not the primary causes here.

Question 25Crop Production and Husbandry

A soil test shows high phosphorus and low potassium. A grower plans a cereal crop. Which fertiliser strategy is most appropriate?

  1. Apply lime without any fertiliser
  2. Apply potassium and reduce or omit phosphorus Correct answer.
  3. Apply a high-phosphorus compound and no potassium
  4. Apply only nitrogen

Explanation

Where soil phosphorus is already high, further phosphorus is unlikely to give an economic response, while low potassium limits yield and should be corrected. Matching fertiliser to soil test results avoids waste and balances nutrition. Blanket compound or nitrogen-only applications ignore the measured deficiencies.

Question 26Crop Production and Husbandry

Which term describes the process by which a cereal seed absorbs water and resumes metabolic activity before the radicle emerges?

  1. Vernalisation
  2. Scarification
  3. Stratification
  4. Imbibition Correct answer.

Explanation

Imbibition is the initial uptake of water by dry seed tissues, driven by the low water potential of the seed colloids, and it triggers the enzyme activity that precedes germination. Vernalisation, stratification and scarification are separate processes concerned with cold requirement, dormancy breaking and seed coat treatment respectively.

Question 27Crop Production and Husbandry

A cereal crop is described as having a 'tillering' growth habit. Which crop is a typical example of a tillering cereal?

  1. Soybean
  2. Maize
  3. Wheat Correct answer.
  4. Sunflower

Explanation

Wheat is a classic tillering cereal: it produces side shoots (tillers) from the crown at the base of the main stem, which contribute substantially to yield. Maize normally produces a single main stem, while sunflower and soybean are broadleaf crops with branching rather than true grass tillers.

Question 28Crop Production and Husbandry

Which soil condition is the primary cause of 'waterlogging' damage to crop roots?

  1. Excessive soil temperature during summer
  2. Deficiency of soil phosphorus
  3. Compaction of the plough pan
  4. Saturation of soil pores with water, displacing air Correct answer.

Explanation

Waterlogging occurs when soil pores are filled with water rather than air, so roots are deprived of oxygen and cannot respire aerobically. The result is impaired nutrient uptake, reduced growth and eventual root death. The other options describe different problems that do not define waterlogging.

Question 29Crop Production and Husbandry

Which of the following is a leguminous forage crop commonly used for hay or silage in temperate livestock systems?

  1. Ryegrass
  2. Barley
  3. Fescue
  4. Lucerne Correct answer.

Explanation

Lucerne (alfalfa) is a deep-rooted perennial legume widely conserved as hay or silage, and its nitrogen-fixing ability makes it valuable in rotations. Ryegrass and fescue are grasses, and barley is a cereal grown mainly for grain or whole-crop silage.

Question 30Crop Production and Husbandry

In a crop rotation, which benefit is most directly associated with including a brassica break crop between successive cereal crops?

  1. Guaranteed higher grain price for the cereal
  2. Elimination of the need for any tillage
  3. Disruption of cereal-specific disease and pest cycles Correct answer.
  4. Increase in soil nitrogen through symbiosis

Explanation

A break crop interrupts the continuity of host plants that sustain cereal pathogens and pests, reducing inoculum build-up in the soil. Brassicas do not fix nitrogen symbiotically, so they do not supply nitrogen in the way a legume does. Tillage requirements and market prices are unrelated to the rotational break effect.

Question 31Crop Production and Husbandry

Which animal is classified as a ruminant?

  1. Sheep Correct answer.
  2. Horse
  3. Pig
  4. Chicken

Explanation

Sheep are true ruminants with a four-compartment stomach in which microbial fermentation of fibrous feed occurs before digestion. Pigs are monogastric, horses are hindgut fermenters without a rumen, and poultry have a different digestive anatomy entirely.

Question 32Crop Production and Husbandry

What is the main purpose of applying lime to an acidic arable soil?

  1. To suppress all weed seeds in the seedbank
  2. To improve drainage of waterlogged clay
  3. To raise soil pH and improve nutrient availability Correct answer.
  4. To increase soil phosphorus content directly

Explanation

Lime neutralises soil acidity, raising pH towards the range where most arable crops access nutrients efficiently and where aluminium toxicity is reduced. It does not supply phosphorus, sterilise the seedbank or change the physical drainage of a soil.

Question 33Crop Production and Husbandry

Which practice is the standard method for controlling weeds between rows of a young vegetable crop without herbicides?

  1. Increasing the sowing rate of the crop
  2. Flood irrigation of the entire field
  3. Mechanical cultivation with a hoe or inter-row cultivator Correct answer.
  4. Applying a nitrogen top dressing

Explanation

Inter-row mechanical cultivation physically uproots or buries weeds while avoiding the crop row, and it is the main non-chemical tool in vegetable production. Flood irrigation, fertiliser application and higher sowing rates do not remove established weeds between rows.

Question 34Crop Production and Husbandry

A dairy farmer wants to reduce the risk of hypocalcaemia (milk fever) around calving. Which approach is most consistent with current nutritional management?

  1. Feeding a diet that induces a mild metabolic acidosis in the dry cow before calving Correct answer.
  2. Removing all forage from the diet for two weeks pre-calving
  3. Restricting water intake in the final week before calving
  4. Increasing dietary calcium to very high levels throughout the dry period

Explanation

A mildly acidogenic pre-calving ration, achieved with anionic salts or appropriate diet formulation, stimulates calcium mobilisation and reduces the risk of milk fever at calving. Feeding very high calcium during the dry period tends to suppress the cow's own calcium mobilisation. Restricting water or removing forage would cause other serious problems.

Question 35Crop Production and Husbandry

A grower wants to reduce nitrate leaching from a sandy field after harvest of a cereal crop. Which practice is most effective?

  1. Sowing a fast-establishing cover crop immediately after harvest Correct answer.
  2. Leaving the field bare over winter
  3. Ploughing the stubble into the soil in late autumn
  4. Applying additional nitrogen fertiliser after harvest

Explanation

A quickly established cover crop takes up residual soil nitrogen and holds it in plant tissue over winter, reducing the amount that can leach below the root zone. Leaving the field bare, adding more nitrogen, or cultivating stubble in late autumn all increase the risk of nitrate loss.

Question 36Crop Production and Husbandry

A wheat crop is at the ear-emergence stage when a foliar fungicide is being considered for Septoria control. Which factor is most important in deciding whether the spray is justified?

  1. The colour of the flag leaf
  2. The number of tillers produced in autumn
  3. Disease pressure on the upper leaves and the protectant interval before the next spray Correct answer.
  4. The price of the previous year's grain

Explanation

Fungicide decisions at ear emergence hinge on the amount of disease already present on the upper leaves and the length of protection the product can give before the next application window. Flag leaf colour, autumn tillering and past grain prices do not predict the need for a spray at this timing.

Question 37Crop Production and Husbandry

A sheep flock grazes a pasture that has been repeatedly set-stocked. Which change in grazing management is most likely to reduce gastrointestinal nematode burdens?

  1. Grazing lambs on the same paddock year after year
  2. Increasing stocking density on the same paddock
  3. Supplying extra concentrate feed at pasture
  4. Rotational grazing with adequate rest periods and clean pasture for lambs Correct answer.

Explanation

Rotational grazing with rest periods reduces the build-up of infective larvae, and moving susceptible lambs to pasture that has not recently carried sheep lowers exposure. Increasing density or repeatedly using the same paddock concentrates contamination, and supplementary feed does not remove parasites already ingested.

Question 38Crop Production and Husbandry

A crop of oilseed rape shows purpling of older leaves and poor early growth on a soil with pH 5.2. Which explanation is most likely?

  1. Nitrogen has been leached entirely from the topsoil
  2. Potassium has been fixed by the clay fraction
  3. Phosphorus is less available at low pH and uptake is impaired Correct answer.
  4. Molybdenum toxicity is inhibiting root growth

Explanation

Phosphorus availability declines sharply in strongly acidic soils because it is bound by aluminium and iron, and phosphorus deficiency commonly shows as purpling of older leaves. Low pH does not remove all soil nitrogen, and molybdenum becomes less, not more, available in acid conditions.

Question 39Crop Production and Husbandry

Which measure best describes the 'feed conversion ratio' in a broiler enterprise?

  1. Total feed cost divided by total labour hours
  2. Percentage of eggs that are cracked at collection
  3. Number of birds placed per square metre of floor
  4. Units of feed consumed per unit of liveweight gain Correct answer.

Explanation

Feed conversion ratio is the weight of feed eaten divided by the liveweight gained, so a lower value indicates more efficient growth. It is a biological efficiency measure and is not defined by labour cost, stocking density or egg quality.

Question 40Crop Production and Husbandry

A potato grower wants to reduce the risk of potato cyst nematode damage in the next crop. Which strategy is most appropriate?

  1. Growing the same susceptible variety more frequently
  2. Growing a resistant potato variety and extending the rotation with non-host crops Correct answer.
  3. Applying extra nitrogen fertiliser before planting
  4. Irrigating more heavily during tuber bulking

Explanation

Potato cyst nematode populations decline slowly in the absence of a host, so extending the rotation with non-host crops and using resistant varieties reduces multiplication and protects yield. More frequent susceptible crops, extra nitrogen or heavier irrigation do not reduce the nematode population.

Question 41Crop Production and Husbandry

A silage clamp is being filled on a warm, dry day. Which practice best supports a successful lactic fermentation?

  1. Wilting the crop to the target dry matter and consolidating it rapidly to exclude air Correct answer.
  2. Applying a high rate of urea to raise the pH
  3. Leaving the crop in the swath for several days to dry out completely
  4. Filling the clamp slowly over a week to allow natural aeration

Explanation

A successful silage fermentation depends on rapid exclusion of oxygen and an appropriate dry matter, so the lactic acid bacteria can lower pH quickly. Slow filling, over-wilting or adding urea to raise pH all favour undesirable clostridial or aerobic activity.

Question 42Crop Production and Husbandry

Which statement best explains why a legume in a grass-legume sward can improve the protein content of the conserved forage?

  1. The legume fixes atmospheric nitrogen and has a higher crude protein concentration than the grass Correct answer.
  2. The legume increases the fibre content of the sward
  3. The legume suppresses all grass growth and is the only species harvested
  4. The legume reduces the water content of the sward

Explanation

Legumes such as white clover fix atmospheric nitrogen through root nodules and typically contain more crude protein than companion grasses, so a mixed sward has higher protein than grass alone. The legume does not eliminate the grass, and it generally lowers rather than raises fibre content.

Question 43Crop Production and Husbandry

A vegetable grower wants to reduce soil-borne disease pressure in a high-value field using a non-chemical approach. Which method relies on solar heating of moist soil under clear plastic?

  1. Fumigation
  2. Crop rotation
  3. Soil solarisation Correct answer.
  4. Biofumigation with brassica green manure

Explanation

Soil solarisation uses clear plastic mulch over moist soil during hot weather to raise soil temperature enough to reduce some pathogens and weed seeds near the surface. Fumigation is a chemical approach, biofumigation relies on glucosinolate breakdown products from brassica residues, and rotation is a spatial and temporal strategy rather than a heating method.

Question 44Crop Production and Husbandry

A herd of beef cows is grazing low-quality mature pasture in late summer. Which supplementation strategy is most likely to improve digestibility of the basal forage?

  1. Feeding extra fibre in the form of straw
  2. Providing a small amount of a nitrogen source such as urea or protein meal Correct answer.
  3. Feeding a large quantity of starch-rich grain at one time
  4. Withholding water to concentrate rumen contents

Explanation

Low-quality forage is limited by nitrogen for rumen microbes, so a small supplement of degradable nitrogen stimulates microbial activity and increases fibre digestion. Large starch loads can depress fibre digestion, withholding water is harmful, and adding straw increases the fibre burden without supplying nitrogen.

Question 45Crop Production and Husbandry

A field trial compares two wheat varieties and reports a 'yield difference significant at P < 0.05'. What does this statement mean?

  1. The two varieties differ by exactly 5% in yield
  2. The trial was free of experimental error
  3. The difference is large enough to be economically worthwhile
  4. The observed difference is unlikely to have arisen by chance alone under the trial conditions Correct answer.

Explanation

A P value below 0.05 indicates that a difference as large as the one observed would occur by chance less than 5% of the time if the varieties were truly equal. It is a statement about statistical evidence, not about economic value, absence of error or the size of the difference.

Question 46Crop Production and Husbandry

A grower notices that a newly planted orchard has poor establishment despite adequate rainfall. A soil test shows a compacted layer at 30 cm depth. Which action best addresses the problem?

  1. Applying surface lime without cultivation
  2. Mulching the soil surface only
  3. Increasing the frequency of shallow irrigation
  4. Deep ripping or subsoiling to fracture the compacted layer before planting Correct answer.

Explanation

A compacted layer restricts root penetration and water movement, so mechanical loosening such as deep ripping or subsoiling is needed to break it. Surface lime, shallow irrigation or surface mulch do not remove a compacted horizon at depth.

Question 47Crop Production and Husbandry

A potato crop is being grown for seed certification. Which factor is most critical to meeting certification standards?

  1. Maximum possible tuber yield per hectare
  2. Uniform tuber size grading
  3. The colour of the foliage at flowering
  4. Low levels of virus infection and freedom from specified diseases in the seed crop Correct answer.

Explanation

Seed potato certification is based primarily on health status, particularly virus incidence and freedom from specified pathogens, because these determine the value of the seed for subsequent crops. Yield, tuber grading and foliage colour are not the certification criteria.

Question 48Crop Production and Husbandry

A grower has a field with a long history of grass weeds and plans to grow a broadleaf break crop. Which herbicide strategy is most consistent with resistance management principles?

  1. Increasing the dose of the same herbicide to overcome poor control
  2. Using herbicides with different modes of action in sequence and in mixture, alongside non-chemical control Correct answer.
  3. Relying on a single post-emergence application each year
  4. Applying the same herbicide every season at the maximum label rate

Explanation

Resistance management depends on diversifying selection pressure, which means rotating and mixing modes of action and integrating cultural controls. Repeating one active ingredient, raising its dose, or relying on a single timing all intensify selection for resistant populations.

Question 49Crop Production and Husbandry

A dairy ration is formulated on paper to meet energy and protein requirements, yet cows show low milk fat and subacute rumen acidosis. Which change is most likely to correct the problem?

  1. Reducing the ration's water content
  2. Replacing forage with more finely ground grain
  3. Increasing the concentrate fraction to raise energy density
  4. Increasing the proportion of physically effective fibre and reducing rapidly fermentable starch Correct answer.

Explanation

Low milk fat with acidosis indicates insufficient effective fibre to stimulate chewing and buffer the rumen, so raising physically effective fibre and cutting rapidly fermentable starch restores rumen pH. Adding more concentrate or finely ground grain worsens acid production, and ration water content is not the cause.

Question 50Crop Production and Husbandry

A crop of winter barley is sown late after a root crop. Which combination of factors most limits yield potential in this situation?

  1. Over-application of a growth regulator
  2. Reduced vernalisation and tillering time combined with a shorter grain-filling period Correct answer.
  3. Too much cold exposure during winter
  4. Excess soil nitrogen and excessive tillering

Explanation

Late sowing shortens the period available for vernalisation, tillering and root development, and it delays canopy establishment so the crop reaches grain filling with less time and resources. Excess nitrogen, excess cold or growth regulator use do not describe the core limitation of a late-sown winter cereal.