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NSSCO Agricultural Science 6115 study materials
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NSSCO Agricultural Science 6115 practice questions

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Question 1Introduction to Agriculture and Sustainable Farming Systems

Which farming system involves growing crops and raising animals on the same farm so that each supports the other?

  1. Plantation agriculture
  2. Mixed farming Correct answer.
  3. Monoculture
  4. Shifting cultivation

Explanation

Mixed farming combines crop production with livestock rearing on one holding, and the two enterprises support each other through manure, fodder and draught power. Monoculture and plantation agriculture concentrate on a single crop, while shifting cultivation rotates land rather than enterprises.

Question 2Introduction to Agriculture and Sustainable Farming Systems

A farmer ploughs along the contour of a slope instead of up and down it. Which soil conservation benefit does this practice mainly provide?

  1. It kills weeds between the crop rows
  2. It reduces the speed of runoff and limits soil erosion Correct answer.
  3. It increases the rate of water infiltration into the subsoil
  4. It raises the soil pH towards neutral

Explanation

Contour ploughing creates ridges that run across the slope, so runoff is slowed and trapped in the furrows rather than rushing downhill. Slower water carries less soil, which reduces erosion. The practice does not directly change pH, kill weeds, or greatly increase subsoil infiltration.

Question 3Introduction to Agriculture and Sustainable Farming Systems

Which of the following is an example of a leguminous green manure crop?

  1. Sunflower
  2. Maize
  3. Mucuna Correct answer.
  4. Cassava

Explanation

Mucuna is a legume often grown and then incorporated into the soil as green manure, adding organic matter and fixing nitrogen through root nodules. Maize, sunflower and cassava are non-legumes grown mainly for grain or roots.

Question 4Introduction to Agriculture and Sustainable Farming Systems

What is the main purpose of crop rotation in a sustainable farming system?

  1. To increase the use of chemical fertilisers each year
  2. To maintain soil fertility and interrupt pest and disease cycles Correct answer.
  3. To keep the same crop in the same field every season
  4. To shorten the growing season of each crop

Explanation

Rotating different crops, especially including legumes and deep-rooted species, maintains soil nutrients and breaks the life cycles of pests and diseases that build up when one crop is repeated. It reduces reliance on chemicals rather than increasing it.

Question 5Introduction to Agriculture and Sustainable Farming Systems

Which term describes the practice of growing trees alongside crops on the same piece of land?

  1. Aquaculture
  2. Hydroponics
  3. Agroforestry Correct answer.
  4. Sericulture

Explanation

Agroforestry deliberately combines trees or shrubs with crops or livestock on the same land so that they interact and provide mutual benefits such as shade, wind protection and organic matter. Hydroponics, aquaculture and sericulture refer to soilless crop production, fish farming and silk production respectively.

Question 6Introduction to Agriculture and Sustainable Farming Systems

A farmer wants to reduce wind erosion on a dry, sandy field. Which measure is most directly effective?

  1. Flood-irrigating the field once a year
  2. Applying lime to raise the soil pH
  3. Deep ploughing along the direction of the prevailing wind
  4. Planting a windbreak of trees or tall grasses at the field edge Correct answer.

Explanation

A windbreak reduces wind speed at ground level, so fewer soil particles are lifted and carried away. Liming, deep ploughing and occasional flooding do not address wind speed, and ploughing with the wind can increase loss of topsoil.

Question 7Introduction to Agriculture and Sustainable Farming Systems

Why is the addition of organic matter such as compost important for sandy soils?

  1. It permanently removes the need for any mineral fertiliser
  2. It converts the sandy soil into heavy clay
  3. It increases the water-holding capacity and nutrient retention of the soil Correct answer.
  4. It raises the soil temperature above the optimum for roots

Explanation

Organic matter binds sandy particles into aggregates that hold more water and exchangeable nutrients, improving fertility and reducing leaching. It does not change the texture class to clay, remove all need for mineral fertiliser, or overheat the soil.

Question 8Introduction to Agriculture and Sustainable Farming Systems

A subsistence farmer grows maize every year on the same small plot and yields keep falling. Which change best addresses the declining fertility while remaining affordable?

  1. Abandon the plot and clear new forest land each year
  2. Spray a broad-spectrum insecticide every fortnight
  3. Alternate maize with a legume such as cowpea and return crop residues to the soil Correct answer.
  4. Grow the same maize variety but plant more densely

Explanation

Including a legume in the sequence adds nitrogen and organic matter and breaks pest cycles, so yields recover without large cash outlay. Denser planting of the same crop and repeated spraying do not restore nutrients, and clearing forest each year is unsustainable.

Question 9Introduction to Agriculture and Sustainable Farming Systems

Which statement best explains why drip irrigation is considered more efficient than furrow irrigation?

  1. It raises the salinity of the soil faster than furrow irrigation
  2. It uses no energy or equipment at all
  3. It delivers water directly to the root zone, reducing evaporation and runoff losses Correct answer.
  4. It floods the whole field so every weed receives water

Explanation

Drip irrigation applies small quantities of water close to each plant's roots, so less is lost to evaporation, deep percolation and runoff. It still needs pumps and equipment, does not flood the field, and generally reduces rather than accelerates salinity build-up.

Question 10Introduction to Agriculture and Sustainable Farming Systems

Which of the following best describes the principle of integrated pest management (IPM)?

  1. Planting only one crop variety to simplify pest control
  2. Combining cultural, biological and chemical methods, with chemicals used only when thresholds are reached Correct answer.
  3. Applying the strongest pesticide as soon as any insect is seen
  4. Removing all chemicals from a farm permanently

Explanation

IPM combines several control methods and uses pesticides only when pest numbers exceed an economic threshold, which reduces cost and resistance. It does not ban chemicals outright, and it avoids routine calendar spraying or monoculture.

Question 11Introduction to Agriculture and Sustainable Farming Systems

A farmer keeps bees near a field of flowering crops. What is the main agricultural benefit of this arrangement?

  1. The bees fix atmospheric nitrogen for the crop
  2. The bees increase the soil pH near the hive
  3. The bees pollinate the flowers, improving seed and fruit set Correct answer.
  4. The bees loosen the soil around the roots

Explanation

Bees are pollinators: as they collect nectar and pollen they transfer pollen between flowers, which improves fertilisation and therefore fruit and seed yield. Pollination does not fix nitrogen, loosen soil or alter pH.

Question 12Introduction to Agriculture and Sustainable Farming Systems

Which farming practice is most likely to cause nitrate pollution of a nearby stream?

  1. Applying nitrogen fertiliser at high rates just before heavy rain Correct answer.
  2. Composting crop residues in a covered pit
  3. Planting a cover crop after harvesting maize
  4. Building a grass strip between the field and the stream

Explanation

Heavy rain soon after high nitrogen application washes nitrate through the soil and into drainage water and streams. Cover crops, grass buffer strips and covered composting all reduce nutrient loss rather than cause it.

Question 13Introduction to Agriculture and Sustainable Farming Systems

In a crop rotation, a cereal such as maize is followed by a legume. Which combination of benefits best explains this sequence?

  1. Both crops compete for the same nutrients, so yields fall
  2. The legume acidifies the soil so the cereal can grow better
  3. The legume adds nitrogen and the cereal uses it, while pest cycles are broken Correct answer.
  4. The cereal adds nitrogen and the legume removes it

Explanation

The legume fixes atmospheric nitrogen through root nodules, leaving nitrogen for the following cereal, and the change of crop interrupts the build-up of cereal-specific pests and diseases. The other statements contradict these processes.

Question 14Introduction to Agriculture and Sustainable Farming Systems

A farmer on a steep slope in a high-rainfall area wants to grow annual crops. Which combination of practices is most appropriate for sustainable production?

  1. Continuous bare fallow during the rainy season
  2. Contour ridges with grass strips and a cover crop between seasons Correct answer.
  3. Deep ploughing along the slope with no protective vegetation
  4. Clean weeding of all vegetation and straight ploughing down the slope

Explanation

Contour ridges slow runoff, grass strips trap soil, and cover crops protect the surface between main crops, together reducing erosion on steep land. Bare fallow, clean weeding and downslope ploughing all expose soil to heavy rain and accelerate loss.

Question 15Introduction to Agriculture and Sustainable Farming Systems

A farmer notices that a pesticide no longer controls a pest that it once killed effectively. Which explanation is most consistent with the principles of pest management?

  1. The crop has started producing its own pesticide
  2. The pest population has developed resistance through repeated selection by the same chemical Correct answer.
  3. The pesticide has become more concentrated during storage
  4. The pest has learned to avoid the pesticide by observing the farmer

Explanation

Repeated use of one active ingredient selects for individuals with natural tolerance, so the population becomes resistant over generations. Pests do not learn by observation, stored pesticide does not become stronger, and crops do not start manufacturing the chemical.

Question 16Introduction to Agriculture and Sustainable Farming Systems

A development project proposes converting a wetland to grow irrigated rice. Which analysis best reflects sustainable farming principles?

  1. Ecosystem services have no economic value and can be ignored
  2. Wetlands provide water storage and habitat, so the trade-offs between food production and ecosystem services must be assessed before conversion Correct answer.
  3. Rice can only be grown after wetlands are drained completely
  4. Wetlands are wasteland, so conversion has no ecological cost

Explanation

Sustainable planning weighs the food-production benefit against the loss of wetland services such as water regulation, flood control and biodiversity. Treating wetlands as wasteland or ignoring ecosystem values contradicts sustainability, and rice is a wetland crop that does not require complete drainage.

Question 17Soil Science and Soil Management

Which soil particle size fraction holds the greatest total surface area and therefore dominates a soil's ability to retain water and nutrients?

  1. Silt
  2. Coarse sand
  3. Fine gravel
  4. Clay Correct answer.

Explanation

Clay particles are the smallest mineral fraction and are plate-shaped, giving them an enormous surface area per unit mass. This surface area, together with charged surfaces, is what allows clay to adsorb water and exchangeable nutrient ions. Sand and gravel are far larger and hold little water or nutrients.

Question 18Soil Science and Soil Management

A farmer's soil feels smooth and floury when rubbed between the fingers, holds together in a ribbon, and shows little grittiness. Which textural class does this best describe?

  1. Sandy loam
  2. Gravelly sand
  3. Silt loam Correct answer.
  4. Loamy sand

Explanation

A smooth, floury feel with strong cohesion and little grittiness is characteristic of silt-dominated soils such as silt loam. Sand feels gritty and does not ribbon well, so sandy classes are excluded. The ribbon behaviour reflects the plasticity contributed by silt and clay rather than by sand.

Question 19Soil Science and Soil Management

Which term describes the arrangement of soil particles into aggregates and the pore spaces between them?

  1. Soil structure Correct answer.
  2. Soil texture
  3. Soil colour
  4. Soil depth

Explanation

Soil structure refers to how individual particles are bound into aggregates (peds) and the resulting arrangement of pores. Texture, by contrast, is the fixed proportion of sand, silt and clay. Structure can be changed by management such as cultivation, organic matter addition and compaction.

Question 20Soil Science and Soil Management

Which soil organism is most important for mixing organic residues into the soil and creating stable aggregates through its casts?

  1. Bacterium
  2. Earthworm Correct answer.
  3. Alga
  4. Nematode

Explanation

Earthworms ingest soil and organic residues and deposit casts that bind particles into stable aggregates. Their burrowing also creates macropores that improve aeration and drainage. Microorganisms decompose organic matter chemically but do not physically mix soil to the same degree.

Question 21Soil Science and Soil Management

What is the main reason a soil with a high proportion of clay holds more water than a sandy soil?

  1. Clay has a much greater surface area and more small pores. Correct answer.
  2. Clay contains more gravel that stores water.
  3. Clay has larger pores that trap water by gravity.
  4. Clay has lower cation exchange capacity.

Explanation

Clay's very small particles give a large surface area and a network of micropores, which hold water strongly against drainage. Sandy soils have large pores that drain freely, so they retain less water. The high surface area also explains clay's high cation exchange capacity.

Question 22Soil Science and Soil Management

Which practice is most effective for raising the organic matter content of a degraded sandy field soil?

  1. Regular additions of well-rotted manure or compost Correct answer.
  2. Increasing irrigation frequency
  3. Repeated deep ploughing each season
  4. Applying lime to raise pH

Explanation

Adding well-rotted manure or compost directly supplies stabilised organic carbon that builds soil organic matter over time. Repeated ploughing does the opposite by accelerating oxidation of organic matter. Lime and irrigation alter pH and water status but add little carbon.

Question 23Soil Science and Soil Management

Which soil horizon is typically the surface layer richest in organic matter and most affected by cultivation?

  1. R horizon
  2. C horizon
  3. B horizon
  4. A horizon Correct answer.

Explanation

The A horizon is the topsoil, where organic residues accumulate and biological activity is greatest, and it is the layer most disturbed by tillage. The B horizon is a subsoil accumulation zone, the C horizon is weathered parent material, and the R horizon is solid rock.

Question 24Soil Science and Soil Management

A soil test reports a pH of 4.8 for a maize field. Which interpretation is most appropriate?

  1. The soil is saline and needs leaching.
  2. The soil is neutral and needs no amendment.
  3. The soil is strongly alkaline and needs gypsum.
  4. The soil is strongly acidic and may limit nutrient availability. Correct answer.

Explanation

A pH of 4.8 is strongly acidic, well below the near-neutral range where most nutrients are most available. At such low pH, aluminium toxicity and reduced availability of phosphorus and molybdenum can limit crop growth. Lime is normally recommended to raise pH towards the target for maize.

Question 25Soil Science and Soil Management

Which material is used to raise the pH of an acidic agricultural soil?

  1. Superphosphate
  2. Elemental sulphur
  3. Agricultural lime Correct answer.
  4. Ammonium sulphate

Explanation

Agricultural lime (calcium carbonate) neutralises soil acidity and raises pH. Ammonium sulphate and elemental sulphur are acidifying materials that lower pH. Superphosphate is a phosphorus fertiliser and does not serve as a liming material.

Question 26Soil Science and Soil Management

Which soil property is measured by the electrical conductivity of a soil-water extract?

  1. Cation exchange capacity
  2. Salinity Correct answer.
  3. Bulk density
  4. Texture

Explanation

Electrical conductivity reflects the concentration of dissolved salts in the soil solution, so it is the standard field measure of salinity. Cation exchange capacity is measured by displacement of exchangeable cations, texture by particle size analysis, and bulk density by mass over volume.

Question 27Soil Science and Soil Management

A farmer wants to reduce soil erosion on a steep slope. Which combination of practices is most effective?

  1. Burning residues and leaving the soil bare
  2. Increasing tillage depth and frequency
  3. Contour ploughing with strips of cover crop and retained residues Correct answer.
  4. Planting up-and-down the slope and removing crop residues

Explanation

Contour ploughing across the slope slows runoff, while cover crops and retained residues protect the surface from raindrop impact and hold soil in place. Together these reduce both splash and rill erosion. Bare, up-and-down cultivation and frequent tillage accelerate soil loss.

Question 28Soil Science and Soil Management

Which process describes the loss of nutrients as water moves downward through the soil profile?

  1. Erosion
  2. Leaching Correct answer.
  3. Nitrification
  4. Capillary rise

Explanation

Leaching is the downward movement of dissolved nutrients beyond the root zone with percolating water. It is a particular concern for highly mobile ions such as nitrate in sandy soils. Capillary rise moves water upward, erosion removes soil particles, and nitrification converts ammonium to nitrate.

Question 29Soil Science and Soil Management

Which soil management practice best improves the structure of a compacted clay soil over several seasons?

  1. Adding organic matter and using deep-rooted cover crops Correct answer.
  2. Continuous heavy grazing
  3. Flooding the field permanently
  4. Frequent traffic with heavy machinery

Explanation

Organic matter promotes aggregate formation and biological activity, while deep-rooted cover crops create channels and help break compacted layers. Together these improve porosity and structure gradually. Heavy traffic and continuous grazing worsen compaction, and permanent flooding damages structure.

Question 30Soil Science and Soil Management

Why is bulk density generally higher in a compacted soil than in a well-structured soil of the same texture?

  1. Compaction adds mineral particles to the soil.
  2. Compaction increases pore space and lowers mass per volume.
  3. Compaction increases organic matter content.
  4. Compaction reduces pore space so the same mass occupies less volume. Correct answer.

Explanation

Bulk density is oven-dry mass divided by total volume. Compaction squeezes out air-filled pores, reducing total volume while mass stays roughly the same, so bulk density rises. This also reduces aeration and root penetration.

Question 31Soil Science and Soil Management

Which cation is held most strongly on soil exchange sites, assuming equal charge and similar concentration?

  1. Calcium ion
  2. Potassium ion
  3. Sodium ion
  4. Aluminium ion Correct answer.

Explanation

Ion exchange selectivity increases with charge and, for equal charge, with ionic size and hydration. Aluminium carries a high charge and is held strongly, which is why it dominates exchange sites in very acidic soils. Monovalent sodium and potassium are held weakly and leach more readily.

Question 32Soil Science and Soil Management

A laboratory reports a cation exchange capacity of 25 cmol(+)/kg for a soil. What does this value indicate?

  1. The soil is strongly saline.
  2. The soil has a high proportion of sand.
  3. The soil has very low nutrient holding ability.
  4. The soil can retain a relatively large amount of exchangeable cations. Correct answer.

Explanation

Cation exchange capacity measures the quantity of exchangeable cations a soil can hold per unit mass. A value of 25 cmol(+)/kg is moderately high and indicates good nutrient retention, typical of soils with appreciable clay and organic matter. Low values are typical of sandy soils.

Question 33Soil Science and Soil Management

Which form of nitrogen is most readily lost through leaching in a sandy soil after heavy rain?

  1. Ammonium held on exchange sites
  2. Organic nitrogen in humus
  3. Nitrogen fixed in legume residues
  4. Nitrate Correct answer.

Explanation

Nitrate carries a negative charge and is not held on negatively charged exchange sites, so it moves freely with drainage water. Ammonium is held by exchange sites, while organic and residue nitrogen must be mineralised before it can leach. Heavy rain after nitrate application therefore risks substantial loss.

Question 34Soil Science and Soil Management

Which statement best explains why water drains slowly through a clay soil?

  1. Clay particles repel water strongly.
  2. Clay has mostly very small pores with high resistance to flow. Correct answer.
  3. Clay contains abundant coarse sand.
  4. Clay has many large continuous pores.

Explanation

Flow through soil depends strongly on pore size. Clay soils are dominated by micropores, which conduct water slowly and hold it tightly by capillary forces, so drainage is poor. Large continuous pores, as in sandy soils, conduct water rapidly.

Question 35Soil Science and Soil Management

Which management strategy is most appropriate for reclaiming a sodic soil with high exchangeable sodium and poor structure?

  1. Increase tillage without drainage
  2. Apply gypsum and leach with good-quality water Correct answer.
  3. Apply more sodium fertiliser
  4. Apply elemental sulphur without drainage

Explanation

Gypsum supplies calcium, which displaces exchangeable sodium from clay surfaces, and leaching then removes the sodium salts. Adequate drainage is essential so leached salts leave the root zone. Simply tilling or adding more sodium does not correct the imbalance.

Question 36Soil Science and Soil Management

Two soils have the same texture but different organic matter contents. Which outcome is expected for the soil with higher organic matter?

  1. Faster leaching of nitrate and lower microbial activity
  2. Higher water holding capacity and higher cation exchange capacity Correct answer.
  3. Higher bulk density and lower porosity
  4. Lower water holding capacity and lower cation exchange capacity

Explanation

Organic matter increases both water holding capacity and cation exchange capacity because humus has a large surface area and many negative charge sites. It also lowers bulk density and supports greater microbial activity. Texture being equal, these differences are attributable to organic matter.

Question 37Soil Science and Soil Management

A soil profile shows a pale, leached E horizon above a reddish B horizon. What does this pattern most likely indicate?

  1. Downward movement of clay, iron or organic matter from the upper layer Correct answer.
  2. Waterlogging with no movement of material
  3. Accumulation of gravel from bedrock weathering
  4. Deposition of fresh volcanic ash at the surface

Explanation

A pale E horizon marks a zone from which clay, iron oxides or organic matter have been removed by leaching. These materials accumulate lower down in the B horizon, giving it a redder or denser appearance. This is characteristic of eluvial-illuvial differentiation in a developing profile.

Question 38Soil Science and Soil Management

A farmer applies a large amount of ammonium-based fertiliser to a well-aerated soil. Which sequence of processes best explains eventual soil acidification?

  1. Nitrification converts ammonium to nitrate and releases hydrogen ions Correct answer.
  2. Denitrification converts nitrate to nitrogen gas and releases hydroxide ions
  3. Ammonium is leached unchanged and removes calcium
  4. Phosphorus fixation releases hydrogen ions

Explanation

In well-aerated soil, nitrifying bacteria oxidise ammonium to nitrate and release hydrogen ions, which lower pH. Continued use of ammonium fertilisers therefore acidifies soil over time. Denitrification occurs in waterlogged conditions and does not explain acidification here.

Question 39Soil Science and Soil Management

Which reasoning best explains why a sandy soil with low cation exchange capacity requires more frequent but smaller fertiliser applications than a clay soil?

  1. Sandy soil holds few exchange sites, so applied nutrients are easily leached below the root zone. Correct answer.
  2. Sandy soil has more exchange sites, so it fixes nutrients too strongly for the crop.
  3. Sandy soil has smaller pores, which trap nutrients away from roots.
  4. Sandy soil has higher organic matter, which immobilises all applied nutrients.

Explanation

Low cation exchange capacity means fewer sites to retain nutrient cations, so they remain in solution and move with drainage water. Split, smaller applications reduce the amount of nutrient exposed to leaching at any one time. Clay soils retain more nutrients and can be fertilised less frequently.

Question 40Soil Science and Soil Management

A farmer notices rills and a fan of deposited soil at the base of a slope after a storm. Which interpretation is most accurate?

  1. Water erosion has detached and transported soil downslope. Correct answer.
  2. The soil has undergone leaching of soluble salts.
  3. The soil has been compacted by machinery.
  4. Wind erosion has removed the topsoil.

Explanation

Rills and a depositional fan are direct evidence of water erosion: raindrop impact detaches particles and runoff carries them downslope before depositing them where the slope flattens. Wind erosion would leave a different pattern, such as drifting and a smooth scoured surface. Leaching and compaction do not create rills or fans.

Question 41Crop Production and Horticulture

Which soil preparation practice is most important before sowing small vegetable seeds such as carrot in a seedbed?

  1. Breaking clods to produce a fine, level tilth Correct answer.
  2. Compacting the surface into a hard crust
  3. Leaving large clods to shade the seedlings
  4. Incorporating fresh manure just before sowing

Explanation

Small seeds need good seed-soil contact, so a fine, level tilth allows even sowing depth and uniform germination. Large clods create air pockets and uneven moisture, while fresh manure placed near seed can burn young roots.

Question 42Crop Production and Horticulture

A farmer wants to raise healthy tomato seedlings for transplanting. Which practice best prevents damping-off in the nursery?

  1. Covering the tray with a sealed plastic sheet for two weeks
  2. Using sterilised seedling medium and avoiding overwatering Correct answer.
  3. Watering heavily every evening
  4. Sowing seed very densely in the tray

Explanation

Damping-off fungi thrive in wet, unsterilised media and crowded seedlings. Sterilised medium combined with moderate watering keeps the collar region dry enough to limit infection.

Question 43Crop Production and Horticulture

Which group of crops is best described as legumes that can add nitrogen to the soil through symbiosis with Rhizobium bacteria?

  1. Cabbage, spinach and lettuce
  2. Maize, sorghum and pearl millet
  3. Cassava, sweet potato and yam
  4. Groundnut, cowpea and soya bean Correct answer.

Explanation

Legumes form root nodules with Rhizobium bacteria, which fix atmospheric nitrogen into forms the plant can use. Cereals, leafy vegetables and root crops do not fix nitrogen in this way.

Question 44Crop Production and Horticulture

What is the main purpose of pricking out seedlings in a nursery?

  1. To remove weeds from between the rows
  2. To harden the seedlings before field transplanting
  3. To increase the number of seeds that germinate
  4. To give seedlings more space and reduce competition Correct answer.

Explanation

Pricking out transfers seedlings into wider spacing so each plant has more light, water and nutrients. It also encourages stronger root and stem development before field planting.

Question 45Crop Production and Horticulture

A horticulturalist wants to propagate a named banana variety that is genetically identical to the parent. Which method is most suitable?

  1. Growing plants from open-pollinated seed
  2. Using suckers or tissue-cultured plantlets Correct answer.
  3. Raising plants from seed collected from the same bunch
  4. Cross-pollinating two selected parents

Explanation

Vegetative propagules such as suckers and tissue-cultured plantlets preserve the exact genotype of the parent. Seed production involves recombination and gives variable offspring.

Question 46Crop Production and Horticulture

Which irrigation method delivers water most efficiently to the root zone of a widely spaced orchard crop while limiting evaporation losses?

  1. Overhead sprinkler irrigation at midday
  2. Furrow irrigation along the whole field
  3. Drip irrigation at each tree Correct answer.
  4. Flood irrigation of the whole block

Explanation

Drip irrigation applies water slowly and directly near the roots, reducing evaporation, runoff and deep percolation. Flood and furrow methods wet large areas that the tree roots do not fully use.

Question 47Crop Production and Horticulture

Which practice is a physical method of weed control in a vegetable plot?

  1. Introducing a rust fungus that attacks the weed
  2. Hand pulling and hoeing Correct answer.
  3. Applying a pre-emergence chemical
  4. Spraying with a selective herbicide

Explanation

Physical or mechanical control removes or destroys weeds by hand or implement without chemicals. Hand pulling and hoeing uproot or cut weeds directly.

Question 48Crop Production and Horticulture

Which soil characteristic is most directly improved by adding well-decomposed compost to a sandy soil?

  1. Slope of the land
  2. Water-holding capacity Correct answer.
  3. Soil pH
  4. Depth of the hardpan

Explanation

Compost adds organic matter that binds sandy particles, increasing the soil's ability to retain moisture and nutrients. It has only a modest effect on pH and cannot change hardpan depth or slope.

Question 49Crop Production and Horticulture

A farmer applies 250 kg of a compound fertiliser containing 12% nitrogen. How much nitrogen is applied?

  1. 30 kg Correct answer.
  2. 120 kg
  3. 250 kg
  4. 12 kg

Explanation

The nitrogen content equals the mass of fertiliser multiplied by the percentage: 250 kg × 0.12 = 30 kg. This calculation allows accurate matching of application to crop requirements.

Question 50Crop Production and Horticulture

A cabbage crop shows pale yellow leaves with older leaves affected first, and growth is stunted. Which nutrient deficiency is most likely?

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

Explanation

Nitrogen is mobile in the plant, so deficiency symptoms appear first on older leaves as yellowing and stunting. Calcium, boron and iron are largely immobile and show symptoms on young tissue first.