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BSEH SS Agriculture practice questions

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Question 1Agriculture and Environment: Scope, Natural Resources, and Sustainability

In the context of sustainable agriculture, which term describes the capacity of a farming system to maintain productivity and resource quality over the long term without depleting the natural resource base?

  1. Intensification
  2. Mechanization
  3. Sustainability Correct answer.
  4. Specialization

Explanation

Sustainability refers to meeting present production needs while preserving the soil, water, and biodiversity resources on which future productivity depends. The other terms describe changes in farming practice or scale rather than long-term resource preservation.

Question 2Agriculture and Environment: Scope, Natural Resources, and Sustainability

Which soil property is most directly improved by maintaining adequate soil organic matter in a sustainable cropping system?

  1. Depth to the water table
  2. Parent material mineralogy
  3. Soil pH buffering to a fixed value
  4. Water-holding capacity and aggregate stability Correct answer.

Explanation

Organic matter binds soil particles into stable aggregates and increases the pore space that holds plant-available water. It does not fix pH at a constant value, alter the underlying parent material, or control groundwater depth.

Question 3Agriculture and Environment: Scope, Natural Resources, and Sustainability

A farmer wants to reduce wind erosion on a bare, sandy field during the fallow season. Which practice most directly addresses this problem?

  1. Establishing a cover crop or surface residue barrier Correct answer.
  2. Increasing irrigation frequency
  3. Applying additional nitrogen fertilizer
  4. Deep plowing before the windy season

Explanation

Wind erosion removes loose surface particles, so keeping the soil covered with living cover or residue reduces the wind velocity at the surface and anchors particles. Fertilizer, deep plowing, and extra irrigation do not protect the surface from wind detachment and transport.

Question 4Agriculture and Environment: Scope, Natural Resources, and Sustainability

Which category of natural resource is groundwater in an aquifer that is recharged more slowly than it is extracted?

  1. A nonrenewable mineral resource
  2. A renewable resource being used unsustainably Correct answer.
  3. A perpetual resource
  4. A manufactured capital resource

Explanation

Groundwater is renewable in principle because recharge occurs, but when extraction outpaces recharge the resource is depleted, so use is unsustainable. It is not a mineral ore, a perpetual flow like solar energy, or a human-made asset.

Question 5Agriculture and Environment: Scope, Natural Resources, and Sustainability

Which agricultural practice best illustrates the principle of conserving biodiversity within a farming landscape?

  1. Removing riparian vegetation to widen channels
  2. Converting all field margins to monoculture turf
  3. Maintaining hedgerows and field margins with native vegetation Correct answer.
  4. Fumigating field borders to eliminate insects

Explanation

Hedgerows and native field margins provide habitat and corridors for pollinators, predators, and other organisms, supporting biodiversity in agricultural landscapes. The other options simplify habitat or remove organisms, reducing biodiversity.

Question 6Agriculture and Environment: Scope, Natural Resources, and Sustainability

A crop rotation alternates a cereal with a legume. Which mechanism most directly explains the agronomic benefit of including the legume?

  1. The legume raises soil pH to alkaline levels
  2. The legume increases soil bulk density
  3. Biological nitrogen fixation adds plant-available nitrogen to the system Correct answer.
  4. The legume eliminates all soil-borne pathogens

Explanation

Legumes form symbioses with rhizobia that fix atmospheric nitrogen into forms usable by plants, reducing reliance on synthetic fertilizer. Rotation also interrupts pest cycles, but it does not eliminate all pathogens, raise pH to alkaline levels, or deliberately increase bulk density.

Question 7Agriculture and Environment: Scope, Natural Resources, and Sustainability

In an integrated pest management program, what is the role of an economic threshold?

  1. It sets the pest population level at which control measures become economically justified Correct answer.
  2. It establishes the price farmers receive for certified organic crops
  3. It specifies the number of pesticide applications permitted per season
  4. It defines the maximum legal residue limit on harvested produce

Explanation

The economic threshold is the pest density at which the cost of control equals the value of the damage prevented, so intervention is warranted only beyond that point. Residue limits, application counts, and crop prices are regulatory or market concepts, not thresholds for pest action.

Question 8Agriculture and Environment: Scope, Natural Resources, and Sustainability

Which irrigation strategy most directly conserves water while maintaining crop yield in a water-scarce region?

  1. Flooding the field continuously to prevent any water stress
  2. Irrigating at midday when evaporation is highest
  3. Scheduling irrigation based on measured soil moisture and crop demand Correct answer.
  4. Applying water uniformly regardless of soil variability

Explanation

Scheduling irrigation from soil-moisture measurements and crop water demand supplies water when the crop needs it, avoiding waste. Continuous flooding, midday application, and uniform application ignoring soil variability all tend to increase losses or reduce efficiency.

Question 9Agriculture and Environment: Scope, Natural Resources, and Sustainability

A farming system that reduces tillage and retains crop residue on the surface is best described as which approach, and what is its primary soil benefit?

  1. Conventional tillage, which increases aeration and residue breakdown
  2. Monoculture, which maximizes single-crop efficiency
  3. Conservation tillage, which reduces erosion and builds organic matter Correct answer.
  4. Flood fallowing, which controls weeds through inundation

Explanation

Conservation tillage leaves residue cover and disturbs soil minimally, which protects the surface from erosion and allows organic matter to accumulate. Conventional tillage buries residue, monoculture concerns crop diversity, and flood fallowing is a water-management practice.

Question 10Agriculture and Environment: Scope, Natural Resources, and Sustainability

Which statement best describes the concept of carrying capacity as applied to a grazing system?

  1. The total forage yield produced in a single season
  2. The maximum stocking rate an area can support without long-term degradation of vegetation and soil Correct answer.
  3. The number of paddocks required to rotate a herd
  4. The maximum number of animals a farmer can afford to purchase

Explanation

Carrying capacity is the stocking level a pasture can sustain indefinitely without degrading the resource base. It is an ecological limit, not a financial constraint, a one-season yield figure, or a paddock-count decision.

Question 11Agriculture and Environment: Scope, Natural Resources, and Sustainability

Which practice most directly reduces nitrate leaching from agricultural fields into groundwater?

  1. Applying nitrogen in a single large dose at planting
  2. Increasing drainage intensity to move water quickly
  3. Leaving soil bare through the winter
  4. Matching nitrogen application to crop uptake and avoiding application before heavy rain Correct answer.

Explanation

Leaching occurs when nitrate remains in the soil solution and moves below the root zone, so synchronizing nitrogen supply with crop demand and avoiding application before rainfall limits losses. Large single doses, bare winter soil, and intensified drainage all increase the risk of nitrate movement to groundwater.

Question 12Agriculture and Environment: Scope, Natural Resources, and Sustainability

A region converts native grassland to annual cropland. Which consequence is most consistent with the principles of natural resource sustainability?

  1. Elimination of the need for external nutrient inputs
  2. Reduction of soil erosion risk on sloping land
  3. Permanent increase in soil organic carbon from annual tillage
  4. Loss of soil organic carbon and reduced habitat for grassland species Correct answer.

Explanation

Plowing native grassland oxidizes stored soil carbon and removes the perennial habitat that grassland species depend on. Annual cropping generally increases reliance on external inputs and, on sloping land, raises erosion risk rather than lowering it.

Question 13Agriculture and Environment: Scope, Natural Resources, and Sustainability

Which combination best represents the three pillars commonly used to evaluate agricultural sustainability?

  1. Yield, machinery, and labor
  2. Soil, seed, and storage
  3. Environmental integrity, economic viability, and social equity Correct answer.
  4. Irrigation, fertilizer, and pesticide

Explanation

Sustainability assessments typically balance environmental, economic, and social dimensions, ensuring that production does not degrade resources, remains profitable, and supports fair livelihoods. The other lists are inputs or production factors rather than sustainability pillars.

Question 14Agriculture and Environment: Scope, Natural Resources, and Sustainability

In a watershed where upstream agriculture increases sediment and nutrient loads, which response best reflects integrated natural resource management?

  1. Coordinating land-use practices across the watershed with buffer strips and nutrient plans Correct answer.
  2. Focusing only on the downstream reservoir with dredging
  3. Treating each farm independently with no coordination on water quality
  4. Banning all agricultural activity in the watershed

Explanation

Integrated watershed management recognizes that upstream land use affects downstream water quality, so coordinated practices such as riparian buffers and nutrient planning address the source of the problem. Isolated farm actions, downstream-only fixes, and blanket bans are not integrated, proportionate approaches.

Question 15Agriculture and Environment: Scope, Natural Resources, and Sustainability

A soil test shows declining organic matter and increasing bulk density under repeated heavy tillage. Which interpretation and response is most defensible?

  1. Organic matter decline increases water storage, so irrigation should be reduced
  2. Bulk density changes are unrelated to management, so no action is needed
  3. Compaction and carbon loss are occurring, so reduced tillage and organic amendments are warranted Correct answer.
  4. The soil is improving, so tillage should be increased

Explanation

Rising bulk density under heavy tillage signals compaction, while falling organic matter indicates carbon loss, both of which degrade structure and productivity. Reduced tillage and organic inputs address the causes, whereas the other interpretations misread the indicators or recommend harmful responses.

Question 16Agriculture and Environment: Scope, Natural Resources, and Sustainability

Which scenario best illustrates the precautionary principle in managing an agricultural input whose long-term ecological effects are uncertain?

  1. Ignoring uncertainty because short-term yields improve
  2. Restricting use until adequate evidence of environmental safety is available Correct answer.
  3. Approving use freely until harm is conclusively proven
  4. Deferring all decisions to future generations

Explanation

The precautionary principle holds that where serious or irreversible harm is possible, lack of full certainty should not delay protective action, so use is limited pending better evidence. Waiting for conclusive proof of harm, ignoring uncertainty, or indefinite deferral does not reflect precaution.

Question 17Soil Science: Formation, Properties, Fertility, and Conservation

Which soil-forming process describes the downward movement of dissolved or suspended material from upper horizons into lower horizons?

  1. Podzolization
  2. Eluviation Correct answer.
  3. Salinization
  4. Illuviation

Explanation

Eluviation is the removal and downward transport of clay, iron, organic matter, or soluble salts from an upper horizon, leaving it bleached or depleted. Illuviation is the complementary accumulation of that material in the horizon below. The two terms are often confused, so distinguish removal from deposition.

Question 18Soil Science: Formation, Properties, Fertility, and Conservation

A soil sample has a dry mass of 150 g and occupies 100 cm³. Assuming a particle density of 2.65 g/cm³, what is the approximate porosity?

  1. 57 percent
  2. 13 percent
  3. 26 percent
  4. 43 percent Correct answer.

Explanation

Bulk density is 150 g ÷ 100 cm³ = 1.5 g/cm³. Porosity = 1 − (bulk density ÷ particle density) = 1 − (1.5 ÷ 2.65) ≈ 0.434, or about 43 percent. Porosity reflects the fraction of soil volume occupied by pore space.

Question 19Soil Science: Formation, Properties, Fertility, and Conservation

Which soil structure type is most commonly associated with favorable aeration and root penetration in temperate agricultural topsoils?

  1. Granular Correct answer.
  2. Columnar
  3. Massive
  4. Platy

Explanation

Granular structure consists of small, rounded aggregates that create abundant interconnected pores, supporting aeration, drainage, and root growth. Platy and massive structures restrict vertical movement, and columnar structure indicates sodium-affected subsoil. Granular aggregates are typical of productive surface horizons.

Question 20Soil Science: Formation, Properties, Fertility, and Conservation

A soil test reports a cation exchange capacity of 12 cmol(+)/kg and 70 percent base saturation. What is the approximate content of exchangeable base cations?

  1. 3.6 cmol(+)/kg
  2. 17 cmol(+)/kg
  3. 8.4 cmol(+)/kg Correct answer.
  4. 12 cmol(+)/kg

Explanation

Base saturation is the proportion of the cation exchange capacity occupied by exchangeable bases such as calcium, magnesium, and potassium. Multiplying 12 cmol(+)/kg by 0.70 gives 8.4 cmol(+)/kg of exchangeable bases. The remainder is occupied mainly by exchangeable aluminum and hydrogen.

Question 21Soil Science: Formation, Properties, Fertility, and Conservation

Which horizon designation indicates a subsurface layer of clay accumulation formed by illuviation?

  1. Bt horizon Correct answer.
  2. A horizon
  3. E horizon
  4. C horizon

Explanation

The subscript t denotes an accumulation of translocated silicate clay, so Bt identifies a clay-enriched argillic horizon. The A horizon is the mineral surface layer, the E horizon is a zone of eluviation, and the C horizon is relatively unweathered parent material. Recognizing horizon suffixes helps interpret soil development and management constraints.

Question 22Soil Science: Formation, Properties, Fertility, and Conservation

In which climate and parent material setting would you expect the fastest rate of soil formation?

  1. Cold, humid climate on granite
  2. Warm, humid climate on loess Correct answer.
  3. Hot, arid climate on basalt
  4. Cold, dry climate on quartz sand

Explanation

Soil formation is fastest where high temperature and abundant moisture accelerate weathering and biological activity, and where parent material is fine-grained and weatherable. Loess provides silt-rich material with large surface area, and a warm humid climate supports rapid mineral alteration and organic inputs. Cold or arid conditions and resistant quartz sand slow development.

Question 23Soil Science: Formation, Properties, Fertility, and Conservation

What is the primary cause of surface crusting and reduced infiltration in intensively cultivated silt loam soils?

  1. Accumulation of organic matter in the Ap horizon
  2. Formation of a spodic horizon
  3. Excessive earthworm burrowing
  4. Aggregate destruction and dispersion at the surface by raindrop impact Correct answer.

Explanation

Raindrop impact and rapid wetting break down surface aggregates, and dispersed clay and silt seal the pores to form a crust. This crust reduces infiltration and can impede seedling emergence. Organic matter accumulation and earthworm activity generally improve surface structure rather than degrade it.

Question 24Soil Science: Formation, Properties, Fertility, and Conservation

Which practice most directly reduces soil erosion on a steep cultivated slope?

  1. Establishing contour strips with perennial vegetation Correct answer.
  2. Removing crop residues after harvest
  3. Planting rows up and down the slope
  4. Increasing tillage depth

Explanation

Contour strips of perennial vegetation slow surface runoff, trap sediment, and reduce slope length, directly cutting erosion. Row orientation up and down the slope concentrates runoff, residue removal exposes the surface, and deeper tillage buries residue and loosens soil. Erosion control combines reduced slope length, cover, and roughness.

Question 25Soil Science: Formation, Properties, Fertility, and Conservation

A soil has a pH of 5.2 and an exchangeable aluminum level high enough to restrict root growth. Which amendment is the standard first step to correct the problem?

  1. Agricultural lime Correct answer.
  2. Elemental sulfur
  3. Gypsum
  4. Ammonium sulfate

Explanation

Agricultural lime raises pH and precipitates or neutralizes exchangeable aluminum, relieving toxicity and improving root growth. Elemental sulfur and ammonium sulfate acidify soil further, and gypsum supplies calcium without raising pH. Lime rate should be set from buffer-pH or exchangeable-aluminum tests.

Question 26Soil Science: Formation, Properties, Fertility, and Conservation

Which mechanism best explains why soils with high organic matter hold more plant-available water than low-organic-matter soils of similar texture?

  1. Organic matter increases particle density
  2. Organic matter raises bulk density
  3. Organic matter decreases cation exchange capacity
  4. Organic matter increases water-holding pore space and aggregation Correct answer.

Explanation

Organic matter promotes aggregation and creates additional micropores and mesopores that retain water at tensions available to plants. It also lowers bulk density and increases total porosity. Particle density is largely unaffected, and organic matter increases rather than decreases cation exchange capacity.

Question 27Soil Science: Formation, Properties, Fertility, and Conservation

Which form of nitrogen is most susceptible to loss through denitrification in waterlogged soil?

  1. Nitrate Correct answer.
  2. Ammonium
  3. Organic nitrogen
  4. Nitrite

Explanation

Under anaerobic conditions, denitrifying bacteria use nitrate as an electron acceptor and convert it to nitrogen gases, which escape to the atmosphere. Ammonium is retained on cation exchange sites and is not directly denitrified. Organic nitrogen must first be mineralized, and nitrite is a transient intermediate.

Question 28Soil Science: Formation, Properties, Fertility, and Conservation

A grower applies 200 kg of a 20-10-10 fertilizer blend. How much actual phosphorus is applied, expressed as P₂O₅?

  1. 20 kg Correct answer.
  2. 40 kg
  3. 200 kg
  4. 10 kg

Explanation

Fertilizer grades give the percentage of nitrogen, available P₂O₅, and soluble K₂O in that order. Twenty percent of 200 kg is 40 kg of N, 10 percent is 20 kg of P₂O₅, and 10 percent is 20 kg of K₂O. The phosphorus figure is therefore 20 kg.

Question 29Soil Science: Formation, Properties, Fertility, and Conservation

Which soil condition most strongly favors phosphorus fixation and reduced availability to crops?

  1. Slightly acidic pH around 6.5
  2. Near-neutral pH with high organic matter
  3. Well-drained sandy soil with low CEC
  4. High pH above 8.5 with free calcium carbonate Correct answer.

Explanation

In calcareous soils at high pH, phosphate precipitates with calcium as sparingly soluble calcium phosphates, reducing availability. At very low pH, phosphorus is fixed by iron and aluminum instead. Near-neutral pH with adequate organic matter generally maximizes phosphorus availability.

Question 30Soil Science: Formation, Properties, Fertility, and Conservation

Which cation dominates the exchange complex of a typical neutral, fertile temperate soil?

  1. Hydrogen
  2. Sodium
  3. Calcium Correct answer.
  4. Aluminum

Explanation

In neutral to slightly alkaline soils, calcium typically occupies the majority of exchange sites, with magnesium second and smaller amounts of potassium and sodium. Hydrogen and aluminum dominate only in acidic soils, and sodium dominates in sodic soils. High calcium saturation favors stable structure and favorable pH.

Question 31Soil Science: Formation, Properties, Fertility, and Conservation

A field shows poor infiltration, a hard subsoil layer, and standing water after rain. Which diagnostic approach best identifies whether a compacted layer is responsible?

  1. Measuring surface pH with a colorimetric kit
  2. Using a penetrometer or soil pit to examine resistance and structure with depth Correct answer.
  3. Testing exchangeable sodium percentage only
  4. Estimating organic matter by loss on ignition

Explanation

A penetrometer profile or a soil pit reveals whether a dense layer with high resistance and platy or massive structure exists at depth. Penetration resistance should be interpreted at consistent moisture because dry soil reads harder. pH, sodium, and organic matter tests provide related but indirect information.

Question 32Soil Science: Formation, Properties, Fertility, and Conservation

Which process converts ammonium to nitrate in well-aerated soil?

  1. Denitrification
  2. Ammonification
  3. Nitrification Correct answer.
  4. Nitrogen fixation

Explanation

Nitrification is the microbial oxidation of ammonium to nitrite and then nitrate by nitrifying bacteria, which require oxygen. Ammonification releases ammonium from organic matter, denitrification reduces nitrate under anaerobic conditions, and nitrogen fixation converts atmospheric nitrogen into ammonia.

Question 33Soil Science: Formation, Properties, Fertility, and Conservation

Why does adding gypsum improve the structure of a sodic soil?

  1. It increases exchangeable sodium percentage
  2. It lowers the electrolyte concentration of the soil solution
  3. It supplies calcium that displaces exchangeable sodium, allowing clay to flocculate Correct answer.
  4. It raises pH and precipitates carbonate

Explanation

Gypsum dissolves to supply calcium, which replaces sodium on exchange sites. With sodium displaced and calcium present, clay particles flocculate into stable aggregates and permeability improves. Leaching then removes the displaced sodium, and gypsum does not raise pH or reduce electrolyte concentration.

Question 34Soil Science: Formation, Properties, Fertility, and Conservation

Which soil texture class generally has the highest plant-available water capacity per unit depth?

  1. Silt loam Correct answer.
  2. Coarse sand
  3. Gravel
  4. Loamy sand

Explanation

Silt loam combines moderate porosity with a pore-size distribution that retains water at tensions plants can extract. Sands drain too freely and hold little available water, while gravel holds almost none. Very fine clays may hold much water but much of it is unavailable because of strong binding.

Question 35Soil Science: Formation, Properties, Fertility, and Conservation

Which statement correctly describes the relationship between soil bulk density and compaction?

  1. Bulk density decreases as compaction increases
  2. Bulk density equals particle density in compacted soil
  3. Bulk density is independent of porosity
  4. Bulk density increases as porosity decreases under compaction Correct answer.

Explanation

Compaction presses soil particles closer together, reducing pore space and increasing dry mass per unit volume, so bulk density rises as porosity falls. Bulk density cannot reach particle density because some pore space always remains. Porosity and bulk density are inversely related.

Question 36Soil Science: Formation, Properties, Fertility, and Conservation

A soil has 2.0 percent organic matter. Using the common approximation that organic matter contains about 58 percent carbon, what is the approximate organic carbon content?

  1. 0.86 percent
  2. 2.0 percent
  3. 1.16 percent Correct answer.
  4. 3.45 percent

Explanation

Organic carbon is estimated by multiplying organic matter by the carbon fraction, 0.58. Thus 2.0 percent × 0.58 = 1.16 percent organic carbon. The inverse factor, 1.72, is used to convert organic carbon back to organic matter.

Question 37Soil Science: Formation, Properties, Fertility, and Conservation

Which management system is most likely to build soil organic matter over time?

  1. Continuous clean tillage with residue removal
  2. Reduced tillage with cover crops and residue retention Correct answer.
  3. Intensive row cropping with bare winter fallow
  4. Annual moldboard plowing and fallow

Explanation

Reduced tillage slows organic matter decomposition, while cover crops and residue retention add carbon inputs. Together these practices shift the carbon balance toward accumulation. Clean tillage, moldboard plowing, and bare fallow all reduce inputs and accelerate loss.

Question 38Soil Science: Formation, Properties, Fertility, and Conservation

Which soil order is characterized by a thick, dark epipedon rich in organic matter and high base saturation, typical of temperate grasslands?

  1. Oxisol
  2. Spodosol
  3. Mollisol Correct answer.
  4. Andisol

Explanation

Mollisols have a thick, dark mollic epipedon with high base saturation and are the classic grassland soils. Oxisols are highly weathered tropical soils, Spodosols have a spodic horizon from illuviation, and Andisols form from volcanic ash. These orders differ mainly in the diagnostic horizons and weathering stage they express.

Question 39Soil Science: Formation, Properties, Fertility, and Conservation

Which factor most limits the reliability of a single soil sample for assessing field fertility?

  1. Spatial variability within the field Correct answer.
  2. Use of a stainless steel auger
  3. Laboratory drying of the sample
  4. Sampling depth greater than 20 cm

Explanation

Soil properties vary spatially because of topography, past management, and parent material, so one sample may not represent the field. Composite sampling from many cores along a defined pattern reduces this error. Depth, auger material, and drying are controlled procedural details rather than the main source of unreliability.

Question 40Soil Science: Formation, Properties, Fertility, and Conservation

Why does waterlogging of a fine-textured soil often increase the availability of iron and manganese while harming crop growth?

  1. Flooding raises redox potential and oxidizes these metals
  2. Flooding increases oxygen diffusion into aggregates
  3. Flooding lowers redox potential, reducing these metals to more soluble forms Correct answer.
  4. Flooding increases soil pH sharply

Explanation

Saturated soil limits oxygen diffusion, so microbes consume remaining oxygen and lower redox potential. Under reducing conditions, iron and manganese oxides are reduced to more soluble forms, raising their concentration. The same anaerobic conditions also favor denitrification and can produce toxic concentrations of reduced metals.

Question 41Crop Production: Field Crops, Cropping Systems, and Package of Practices

In the rice–wheat cropping system of the Indo-Gangetic Plains, which practice most directly reduces the turnaround time between rice harvest and wheat sowing?

  1. Flood irrigation immediately after rice harvest
  2. Conventional tillage with two passes of a disc harrow
  3. Zero-till drilling of wheat into standing stubble Correct answer.
  4. Burning of rice straw in the field

Explanation

Zero-till drilling lets wheat be sown directly into the anchored residue of the preceding rice crop, eliminating repeated tillage passes and conserving soil moisture. This advances sowing date and avoids the yield penalty associated with late-planted wheat in the rice–wheat belt.

Question 42Crop Production: Field Crops, Cropping Systems, and Package of Practices

Which crop is classically grown as a kharif pulse in the rainfed areas of central India, maturing on residual soil moisture after the monsoon?

  1. Lentil
  2. Chickpea
  3. Field pea
  4. Pigeonpea Correct answer.

Explanation

Pigeonpea is a long-duration kharif pulse sown with the onset of monsoon and harvested late in the season, often using residual moisture. Chickpea, lentil and field pea are predominantly rabi crops sown on stored moisture after the monsoon.

Question 43Crop Production: Field Crops, Cropping Systems, and Package of Practices

A grower wants to include a legume in a cereal-based rotation mainly to improve soil nitrogen for the following cereal. Which mechanism explains the benefit?

  1. Greater uptake of soil nitrate by the legume, leaving more for the cereal
  2. Release of nitrogen bound in soil organic matter by tillage
  3. Direct transfer of fixed nitrogen through root exudates during the same season
  4. Symbiotic fixation of atmospheric nitrogen by rhizobia in root nodules Correct answer.

Explanation

Grain and forage legumes form nodules with rhizobia that reduce atmospheric N2 to ammonia, which is assimilated into plant tissue. When the legume residue decomposes, part of this fixed nitrogen becomes available to the succeeding cereal.

Question 44Crop Production: Field Crops, Cropping Systems, and Package of Practices

Which of the following is the standard seed rate range for direct-seeded rice under dry conditions in the Indo-Gangetic Plains?

  1. 60–80 kg/ha Correct answer.
  2. 20–25 kg/ha
  3. 100–120 kg/ha
  4. 5–10 kg/ha

Explanation

Dry direct-seeded rice typically uses a higher seed rate than transplanted rice, commonly around 60–80 kg/ha, to compensate for uneven establishment and bird or pest damage. Transplanted rice uses much lower rates because seedlings are raised in a nursery.

Question 45Crop Production: Field Crops, Cropping Systems, and Package of Practices

In a maize–wheat rotation, which practice best conserves soil moisture for wheat sown after maize harvest?

  1. Retaining maize residue as surface mulch Correct answer.
  2. Deep ploughing to 30 cm before sowing
  3. Burning maize stover before sowing
  4. Removing all crop residue and leaving bare soil

Explanation

Surface residue mulch reduces evaporation, moderates soil temperature and improves infiltration, so more stored moisture is available to the following wheat crop. Residue retention also protects the soil surface from crusting and erosion.

Question 46Crop Production: Field Crops, Cropping Systems, and Package of Practices

Which agronomic intervention is the most appropriate first step to control a severe infestation of Phalaris minor in wheat?

  1. Flood irrigation to drown the weed seedlings
  2. Application of a broad-spectrum contact herbicide after crop emergence
  3. Hand weeding only after the weed has set seed
  4. Use of a selective herbicide such as clodinafop or sulfosulfuron at the recommended stage Correct answer.

Explanation

Phalaris minor is a grassy weed of wheat and is managed with selective grass herbicides applied at the correct growth stage of the weed. Rotating herbicide modes of action also helps delay resistance, which is widespread in this species.

Question 47Crop Production: Field Crops, Cropping Systems, and Package of Practices

Which of the following is a long-duration sugarcane planting method that uses a nursery of pre-germinated settlings before field transplanting?

  1. Polybag settlings transplanting Correct answer.
  2. Flat planting
  3. Ring pit planting
  4. Trench planting

Explanation

Raising settlings in polybags or nursery beds and transplanting them to the field improves establishment, saves seed cane and gives better uniformity. Flat, trench and ring pit planting all involve direct field planting of setts.

Question 48Crop Production: Field Crops, Cropping Systems, and Package of Practices

Which practice is recommended for maintaining seed viability of oilseed crops such as mustard during storage?

  1. Storing in moist jute bags at high humidity
  2. Mixing fresh seed with old seed to reduce cost
  3. Drying seed to safe moisture and storing in airtight containers Correct answer.
  4. Storing in direct sunlight to keep the seed warm

Explanation

Oilseeds are prone to rancidity and fungal attack, so seed must be dried to a safe moisture level and kept in airtight, cool storage. This slows respiration and prevents mould growth that destroys viability.

Question 49Crop Production: Field Crops, Cropping Systems, and Package of Practices

A farmer grows rice in kharif and then leaves the field fallow in rabi. Which term best describes this cropping pattern?

  1. Relay cropping
  2. Double cropping
  3. Mixed cropping
  4. Sole cropping with a fallow period Correct answer.

Explanation

Growing a single crop per year with the rest of the year left uncropped is sole cropping with a fallow period. It differs from double cropping, where two crops are taken from the same field in a year.

Question 50Crop Production: Field Crops, Cropping Systems, and Package of Practices

In a rice–wheat system, which nutrient management issue is most characteristic of continuous puddled rice followed by wheat?

  1. Depletion of potassium in the plough layer
  2. Build-up of available phosphorus in the surface layer
  3. Zinc deficiency induced by prolonged flooding Correct answer.
  4. Excess sulphur accumulation in the subsoil

Explanation

Continuous submerged rice culture favours reduction reactions that reduce zinc availability, and zinc deficiency is a well-recognised constraint in rice–wheat systems. Correction usually involves soil application of zinc sulphate or foliar sprays.