- Growing different crops in succession on a piece of land in a planned manner is called:
a) Monocropping
b) Crop rotation
c) Intercropping
d) Mixed cropping
Answer: b) Crop rotation
Explanation: Crop rotation is the practice of growing different types of crops in the same area in sequenced seasons. It helps maintain soil fertility, reduce pest and disease buildup, and optimize resource use compared to growing the same crop repeatedly.
- The classic Norfolk rotation (four-course system) includes:
a) Wheat, barley, oats, rye
b) Turnips, barley, clover, wheat
c) Rice, wheat, pulses, fallow
d) Maize, beans, squash, sunflower
Answer: b) Turnips, barley, clover, wheat
Explanation: The Norfolk four-course rotation, developed in England during the Agricultural Revolution, rotated turnips, barley, clover, and wheat. Turnips were fed to livestock, barley used for malting, clover fixed nitrogen and provided fodder, and wheat was the cash crop.
- Which of the following is NOT an advantage of crop rotation?
a) Improvement in soil fertility
b) Reduction in pest and disease incidence
c) Maximum use of farm resources throughout the year
d) Complete elimination of all weeds
Answer: d) Complete elimination of all weeds
Explanation: While crop rotation helps reduce weed pressure by alternating crops with different growth habits and management practices, it cannot completely eliminate all weeds. Some weeds adapt to multiple crops or survive through various means.
- Inclusion of legumes in crop rotation is beneficial primarily because they:
a) Require less water
b) Fix atmospheric nitrogen
c) Have deep root systems
d) Grow quickly
Answer: b) Fix atmospheric nitrogen
Explanation: Legumes form symbiotic relationships with Rhizobium bacteria in their root nodules to fix atmospheric nitrogen into plant-available forms. This reduces the need for nitrogen fertilizers in subsequent crops in the rotation.
- Growing crops in a sequence that includes a fallow period is called:
a) Continuous cropping
b) Rotational fallowing
c) Ley farming
d) Cover cropping
Answer: b) Rotational fallowing
Explanation: Rotational fallowing involves leaving land uncropped for one or more seasons to accumulate soil moisture, allow organic matter decomposition, or break pest cycles. This practice is common in dryland agriculture where moisture conservation is critical.
- In crop rotation, deep-rooted crops should be followed by:
a) Deep-rooted crops only
b) Shallow-rooted crops
c) No crops
d) Perennial crops only
Answer: b) Shallow-rooted crops
Explanation: Deep-rooted crops (like sunflower, pigeonpea) should be followed by shallow-rooted crops (like wheat, chickpea) to utilize nutrients from different soil layers efficiently. This prevents the depletion of nutrients from any single soil depth.
- Which of the following is a cereal-legume crop rotation?
a) Rice-Rice
b) Wheat-Maize
c) Rice-Wheat-Green gram
d) Sugarcane-Sugarcane
Answer: c) Rice-Wheat-Green gram
Explanation: Rice-Wheat-Green gram is an excellent cereal-legume rotation. Rice and wheat are cereals (grasses), while green gram is a legume that fixes atmospheric nitrogen, benefiting the following crops and improving soil health.
- The principle of crop rotation that includes alternating exhaustive crops with restorative crops means:
a) Alternating cereals with legumes
b) Alternating shallow-rooted with deep-rooted crops
c) Alternating high nutrient-demanding crops with low nutrient-demanding crops
d) All of the above
Answer: d) All of the above
Explanation: The principle of alternating exhaustive with restorative crops encompasses several aspects: legumes restore nitrogen (cereals exhaust it); deep-rooted crops access subsoil nutrients (shallow crops restore surface); and high-demand crops should follow low-demand crops.
- A three-year rotation of maize – wheat – green gram is an example of:
a) Monocropping
b) Relay cropping
c) Double cropping
d) Multiple cropping
Answer: d) Multiple cropping
Explanation: Multiple cropping refers to growing more than one crop on the same land in a year. Maize-wheat-green gram in sequence over three years, if grown in one year, would be triple cropping. The rotation plan over multiple years is still part of multiple cropping systems.
- Which crop is known as a “soil-exhausting” crop in rotation?
a) Sunhemp
b) Cowpea
c) Sugarcane
d) Guar
Answer: c) Sugarcane
*Explanation: Sugarcane is considered a soil-exhausting crop because it removes large quantities of nutrients (especially potassium) from the soil, remains in the field for 10-18 months, and has extensive root system that depletes nutrients from deeper soil layers.*
- Growing two or more crops simultaneously on the same land with a definite row pattern is:
a) Crop rotation
b) Intercropping
c) Mixed cropping
d) Relay cropping
Answer: b) Intercropping
Explanation: Intercropping involves growing two or more crops simultaneously on the same land with a definite row arrangement (e.g., 1:1, 2:1). It differs from mixed cropping (no distinct row arrangement) and relay cropping (second crop planted before first harvest).
- Which of the following is a suitable crop to include in rotation for controlling nematodes?
a) Wheat
b) Marigold
c) Rice
d) Maize
Answer: b) Marigold
Explanation: Marigold (Tagetes spp.) produces thiophene compounds that suppress nematode populations in soil. Including marigold in rotation helps control root-knot nematodes and other plant-parasitic nematodes, serving as a bio-fumigant.
- The system where grass-legume mixture is grown for 2-3 years followed by annual crops is called:
a) Ley farming
b) Pastoral farming
c) Shifting cultivation
d) Organic farming
Answer: a) Ley farming
Explanation: Ley farming alternates periods of grass-legume pasture (ley) with periods of arable cropping. The pasture phase restores soil fertility through organic matter addition and nitrogen fixation, benefiting subsequent grain or vegetable crops.
- In a crop rotation, crops of the same family should not be grown in succession because they:
a) Require similar nutrients
b) Attract similar pests and diseases
c) Have similar root systems
d) All of the above
Answer: d) All of the above
Explanation: Crops from the same family (e.g., Solanaceae: potato, tomato, brinjal) should be rotated with other families because they have similar nutrient demands, are susceptible to the same pests and diseases, and extract nutrients from similar soil depths.
- Rice-wheat is the most important cropping system in:
a) Southern India
b) Indo-Gangetic plains
c) Western India
d) Northeastern hills
Answer: b) Indo-Gangetic plains
Explanation: The rice-wheat cropping system is predominant in the Indo-Gangetic plains covering parts of Punjab, Haryana, Uttar Pradesh, Bihar, and West Bengal in India, and extending into Pakistan, Nepal, and Bangladesh. It’s crucial for food security in South Asia.
- The main objective of including a fallow period in crop rotation is:
a) To give land rest
b) To accumulate soil moisture
c) To control weeds
d) All of the above
Answer: d) All of the above
Explanation: Fallow periods serve multiple purposes: they allow soil moisture accumulation (especially in drylands), give land rest from continuous cropping, help control weeds and pests by breaking their life cycles, and allow organic matter decomposition and nutrient release.
- Which of the following rotations is likely to deplete soil fertility most rapidly?
a) Rice – Wheat – Green gram
b) Maize – Potato – Onion
c) Sorghum – Chickpea – Fallow
d) Cotton – Wheat – Cowpea
Answer: b) Maize – Potato – Onion
Explanation: Maize, potato, and onion are all heavy feeders that remove large quantities of nutrients from soil. Without a legume or restorative crop, this rotation would rapidly deplete soil fertility. Legume inclusion (options a and d) helps restore nitrogen.
- The term “catch crop” refers to:
a) A crop grown to trap insects
b) A fast-growing crop grown between main crops
c) A crop that catches and fixes nitrogen
d) A crop harvested for animal feed
Answer: b) A fast-growing crop grown between main crops
Explanation: A catch crop is a fast-growing crop (often green manure or fodder) grown in the space between two main crops to utilize residual nutrients, prevent nutrient leaching, and provide additional biomass. It’s “caught” in the otherwise fallow period.
- Growing two or more crops in the same field in a year is called:
a) Mono-cropping
b) Multiple cropping
c) Relay cropping
d) Alley cropping
Answer: b) Multiple cropping
Explanation: Multiple cropping is the practice of growing two or more crops on the same land in one year (cropping intensity >100%). It includes double cropping (two crops), triple cropping (three crops), and relay cropping where crops overlap in time.
- In the rice-wheat cropping system, the inclusion of mungbean as a summer crop is beneficial because:
a) It adds organic matter
b) It fixes atmospheric nitrogen
c) It breaks pest cycles
d) All of the above
Answer: d) All of the above
*Explanation: Including mungbean (green gram) in the rice-wheat system during the summer gap adds organic matter through residues, fixes atmospheric nitrogen (40-60 kg/ha), breaks pest cycles by providing a non-host crop, and provides additional grain/fodder.*
- Which of the following is a restorative crop?
a) Sorghum
b) Sunflower
c) Cowpea
d) Cotton
Answer: c) Cowpea
Explanation: Cowpea is a leguminous crop that fixes atmospheric nitrogen through symbiosis with Rhizobium bacteria. It adds organic matter and nitrogen to the soil, improving fertility for subsequent crops. It’s considered a restorative or soil-improving crop.
- Crop rotation helps in weed management by:
a) Changing the competitive environment
b) Allowing use of different herbicides
c) Disrupting weed life cycles
d) All of the above
Answer: d) All of the above
Explanation: Crop rotation aids weed management through multiple mechanisms: different crops compete differently with weeds, allow rotation of herbicides with different modes of action (reducing resistance), and disrupt weed life cycles by changing timing of tillage and harvest.
- In a crop rotation plan, the most demanding crop in terms of nutrients should be grown:
a) First after a fallow or legume
b) Last in the rotation
c) In the middle of rotation
d) Anytime, nutrient demand doesn’t matter
Answer: a) First after a fallow or legume
Explanation: The most nutrient-demanding crop (e.g., maize, sugarcane) should be grown immediately after a fallow period or a legume crop when soil fertility is highest. This maximizes yield potential and efficient use of accumulated nutrients and soil moisture.
- Potato should not be grown after tomato in rotation because:
a) Both are exhaustive crops
b) Both belong to the Solanaceae family and share diseases
c) Both have similar nutrient requirements
d) Both require similar irrigation schedules
Answer: b) Both belong to the Solanaceae family and share diseases
Explanation: Potato and tomato belong to the Solanaceae family and are susceptible to common diseases like early blight (Alternaria), late blight (Phytophthora), bacterial wilt, and nematodes. Growing them in succession increases disease pressure in the soil.
- The system of growing crops in a sequence that includes green manuring crops is beneficial because:
a) It adds organic matter
b) It improves soil structure
c) It provides nitrogen
d) All of the above
Answer: d) All of the above
Explanation: Green manuring crops (like sunhemp, dhaincha) incorporated into soil add organic matter (improving structure and water-holding capacity), provide nitrogen through biological fixation, recycle nutrients from deeper layers, and suppress weeds during their growth.
Agronomy MCQs – Set 4: Irrigation and Water Management (25 Questions)
- The scientific application of water to land for crop production is called:
a) Precipitation
b) Irrigation
c) Drainage
d) Transpiration
Answer: b) Irrigation
Explanation: Irrigation is the artificial application of water to soil or land for supporting crop growth. It supplements natural rainfall and ensures adequate moisture for optimal plant growth and development, especially in areas with insufficient or erratic rainfall.
- Which method of irrigation is most water-efficient?
a) Flood irrigation
b) Furrow irrigation
c) Drip irrigation
d) Sprinkler irrigation
Answer: c) Drip irrigation
*Explanation: Drip irrigation (micro-irrigation) delivers water directly to the plant root zone through emitters, with efficiency of 90-95%. It minimizes losses through evaporation, runoff, and deep percolation, making it the most water-efficient method.*
- The total water requirement of a crop includes:
a) Evaporation from soil
b) Transpiration by the crop
c) Water used for metabolic activities
d) All of the above
Answer: d) All of the above
Explanation: Total water requirement of a crop includes water lost through evapotranspiration (evaporation from soil + transpiration from plants), water used in metabolic processes, and water needed for special operations like puddling in rice or leaching of salts.
- The ratio of water output (beneficial use) to water input in irrigation is called:
a) Water use efficiency
b) Irrigation efficiency
c) Conveyance efficiency
d) Application efficiency
Answer: b) Irrigation efficiency
Explanation: Irrigation efficiency is the ratio of water beneficially used (stored in root zone for crop use) to the total water applied through irrigation. It accounts for losses during conveyance, application, and distribution. Higher efficiency means less water waste.
- Which irrigation method is best suited for undulating topography and sandy soils?
a) Flood irrigation
b) Furrow irrigation
c) Sprinkler irrigation
d) Basin irrigation
Answer: c) Sprinkler irrigation
Explanation: Sprinkler irrigation is suitable for undulating topography because it doesn’t require land leveling, and for sandy soils because water can be applied at rates less than infiltration rate, preventing runoff and deep percolation losses.
- The moisture content at which plants permanently wilt and cannot recover unless water is added is called:
a) Field capacity
b) Permanent wilting point
c) Available water
d) Saturation point
Answer: b) Permanent wilting point
Explanation: Permanent wilting point (PWP) is the soil moisture content at which plants wilt and cannot recover turgidity even when placed in a saturated atmosphere unless water is added to the soil. It occurs at approximately 15 atmospheres tension.
- The interval between two consecutive irrigations is called:
a) Rotation period
b) Irrigation frequency
c) Irrigation interval
d) Duty period
Answer: c) Irrigation interval
Explanation: Irrigation interval (or frequency) is the time gap between two successive irrigations. It depends on soil type, crop, climate, and growth stage. Shorter intervals are needed in sandy soils, during peak growth, and in hot, dry weather.
- Which irrigation method is commonly used for rice cultivation?
a) Furrow irrigation
b) Drip irrigation
c) Basin irrigation
d) Sprinkler irrigation
Answer: c) Basin irrigation
Explanation: Rice is typically grown under flooded conditions, and basin irrigation (also called check-basin or ponding) is the most common method. Level plots surrounded by bunds retain standing water, which is essential for rice in the traditional system.
- The depth of irrigation water required to bring the root zone soil to field capacity is called:
a) Irrigation requirement
b) Delta of water
c) Duty of water
d) Consumptive use
Answer: a) Irrigation requirement
Explanation: Irrigation requirement is the depth of water needed to bring the soil moisture in the root zone to field capacity. It’s calculated as the difference between field capacity and the existing soil moisture content before irrigation.
- Which of the following is NOT an advantage of sprinkler irrigation?
a) Suitable for all soil types
b) Uniform water distribution
c) Low initial cost
d) Can apply fertilizers through system
Answer: c) Low initial cost
Explanation: Sprinkler irrigation actually has relatively high initial investment for equipment (pumps, pipes, sprinklers). However, it offers advantages like suitability for various soils, uniform distribution, and fertigation capability, with water savings justifying the cost in many situations.
- The relationship between the area irrigated and the quantity of water required during the entire growth period of a crop is expressed as:
a) Base period
b) Delta
c) Duty
d) Kor depth
Answer: c) Duty
Explanation: Duty of water is the relationship between the area irrigated (in hectares) and the continuous flow of water (in cubic meters per second or liters per second) required throughout the crop growth period. It’s expressed as hectares per cumec.
- The total depth of water required by a crop during its entire growing period is called:
a) Delta
b) Duty
c) Base period
d) Kor depth
Answer: a) Delta
Explanation: Delta (Δ) is the total depth of water (usually in cm or m) required by a crop during its entire growing period from sowing to harvest. It includes water for evapotranspiration, puddling (for rice), leaching, and other losses.
- The first watering given to a crop after sowing when the soil moisture is inadequate for germination is called:
a) Kor watering
b) Pallavi watering
c) Life-saving irrigation
d) Pre-sowing irrigation
Answer: b) Pallavi watering
Explanation: Pallavi watering (also called “first watering” in some regions) is the initial irrigation given after sowing when soil moisture is insufficient for proper germination and establishment. It’s critical for ensuring uniform crop emergence.
- The most critical stage for irrigation in wheat is:
a) Germination
b) Tillering
c) Crown root initiation
d) Flowering
Answer: c) Crown root initiation (CRI)
*Explanation: Crown root initiation (CRI) stage, occurring about 20-25 days after sowing, is the most critical for irrigation in wheat. Moisture stress at this stage severely affects tillering and yield potential. It’s often called the “irrigation-sensitive stage.”*
- For most crops, the critical period for moisture stress is:
a) Vegetative stage
b) Reproductive stage (flowering and grain filling)
c) Maturity stage
d) Germination stage
Answer: b) Reproductive stage (flowering and grain filling)
Explanation: Most crops are most sensitive to moisture stress during the reproductive stage (flowering, pollination, and grain filling). Stress during this period directly affects yield by reducing pollination, grain set, and grain development.
- The technique of irrigating alternate furrows instead of every furrow is called:
a) Furrow irrigation
b) Alternate furrow irrigation
c) Surge irrigation
d) Corrugation irrigation
Answer: b) Alternate furrow irrigation
*Explanation: Alternate furrow irrigation involves wetting only alternate furrows, leaving the others dry. This can save 25-35% water compared to every-furrow irrigation with minimal yield reduction, as water moves laterally to the dry furrows.*
- The moisture content at which a soil is saturated and all pores are filled with water is called:
a) Field capacity
b) Saturation capacity
c) Permanent wilting point
d) Available water capacity
Answer: b) Saturation capacity
Explanation: Saturation capacity (also called maximum water holding capacity) is the moisture content when all soil pores are completely filled with water. This occurs immediately after heavy rain or irrigation, before gravitational drainage begins.
- Which of the following is NOT a method to improve irrigation efficiency?
a) Lining of canals
b) Laser land leveling
c) Continuous flooding
d) Drip irrigation
Answer: c) Continuous flooding
Explanation: Continuous flooding (especially in rice) results in high water losses through deep percolation and evaporation. It’s NOT an efficient irrigation method. Canals lining reduces seepage losses, laser leveling ensures uniform water distribution, and drip irrigation minimizes all losses.
- The process of applying water to crops through perforated pipes laid on the ground surface is called:
a) Drip irrigation
b) Sprinkler irrigation
c) Perforated pipe irrigation
d) Sub-irrigation
Answer: c) Perforated pipe irrigation
Explanation: Perforated pipe irrigation (also called “porous pipe” or “hole pipe” irrigation) involves laying pipes with holes or perforations along the field. Water flows out through holes and runs down the furrows or between crop rows.
- The water available to plants between field capacity and permanent wilting point is called:
a) Gravitational water
b) Available soil water
c) Hygroscopic water
d) Capillary water
Answer: b) Available soil water
Explanation: Available soil water (or available water capacity) is the amount of water held in soil between field capacity (upper limit) and permanent wilting point (lower limit) that plants can extract for growth and transpiration.
- Which method of irrigation is most suitable for orchards on sloping lands?
a) Check basin
b) Furrow
c) Contour terrace
d) Ring basin
Answer: d) Ring basin
Explanation: Ring basin (or ring method) is ideal for orchards on sloping lands. Basins are made around individual trees in a circular or square shape, allowing water to be applied directly to the root zone without causing erosion on slopes.
- The process of removing excess water from the soil surface or root zone is called:
a) Irrigation
b) Drainage
c) Evaporation
d) Transpiration
Answer: b) Drainage
Explanation: Drainage is the natural or artificial removal of excess water from the soil surface or root zone. It prevents waterlogging, ensures adequate aeration for root respiration, and helps in salinity management in irrigated areas.
- The water use efficiency (WUE) is defined as:
a) Water applied / Yield obtained
b) Yield obtained / Water used
c) Water stored / Water applied
d) Evapotranspiration / Yield
Answer: b) Yield obtained / Water used
Explanation: Water use efficiency (WUE) is the ratio of crop yield (economic or biomass) to the amount of water used (evapotranspiration or total water applied). Higher WUE means more crop per drop – producing more yield with less water.
- Which crop has the highest water requirement?
a) Wheat
b) Maize
c) Sugarcane
d) Groundnut
Answer: c) Sugarcane
*Explanation: Among common crops, sugarcane has one of the highest water requirements (1500-2500 mm depending on climate and duration). Rice also has high requirement (1000-1500 mm), while millets and pulses have relatively lower water requirements.*
- The technique of applying less water than the full crop water requirement, especially in deficit rainfall areas, is called:
a) Protective irrigation
b) Deficit irrigation
c) Life-saving irrigation
d) Supplemental irrigation
Answer: b) Deficit irrigation
Explanation: Deficit irrigation is an optimization strategy where irrigation is applied below full crop water requirements, especially during drought or water scarcity. Plants are subjected to some level of moisture stress, accepting some yield reduction for water savings.
