What does the number sequence on an NPK fertilizer grade represent?
A N, P₂O₅, and K₂O percentages
B Seed, soil, and water ratios
C Carbon, hydrogen, and oxygen
D Moisture, ash, and protein
Answer: A. N, P₂O₅, and K₂O percentages. FAO describes fertilizer grade in the order nitrogen, phosphate expressed as P₂O₅, and potash expressed as K₂O.
For a 12-32-16 grade, what does the first number indicate?
A Moisture percentage by weight
B Phosphate percentage by weight
C Nitrogen percentage by weight
D Potash percentage by weight
Answer: C. Nitrogen percentage by weight. The first number in an NPK grade represents nitrogen content by weight.
Which description fits a straight fertilizer?
A Contains all micronutrients
B Has no declared nutrients
C Contains only organic matter
D Supplies one primary nutrient
Answer: D. Supplies one primary nutrient. FAO classifies straight fertilizers as supplying one of the three primary nutrients N, P, or K.
How does a compound fertilizer differ from a straight fertilizer?
A It contains no mineral nutrients
B It supplies multiple primary nutrients
C Made only from manure
D It supplies water only
Answer: B. It supplies multiple primary nutrients. Compound or complex fertilizers contain at least two of the primary nutrients.
Urea is mainly a source of which nutrient?
A Calcium
B Nitrogen
C Phosphorus
D Potassium
Answer: B. Nitrogen. Urea is a concentrated nitrogen fertilizer.
Which two primary nutrients are supplied by DAP?
A Nitrogen and phosphorus
B Sulfur and magnesium
C Carbon and oxygen
D Potassium and calcium
Answer: A. Nitrogen and phosphorus. Diammonium phosphate supplies nitrogen and phosphorus.
Muriate of potash is mainly used to supply what?
A Nitrogen
B Potassium
C Phosphorus
D Boron
Answer: B. Potassium. Muriate of potash is potassium chloride, a common potassium fertilizer.
What nutrient pair is supplied by sulfate of potash?
A Iron and zinc
B Nitrogen and phosphorus
C Calcium and boron
D Potassium and sulfur
Answer: D. Potassium and sulfur. Sulfate of potash supplies potassium and sulfur.
Which primary nutrient is supplied by single superphosphate?
A Potassium
B Nickel
C Phosphorus
D Nitrogen
Answer: C. Phosphorus. Single superphosphate is a phosphorus fertilizer and also contains calcium and sulfur.
What does an NPK grade list first?
A Potash
B Nitrogen
C Phosphate
D Moisture
Answer: B. Nitrogen. The standard NPK sequence starts with nitrogen, followed by phosphate and potash.
Which materials commonly contribute to farmyard manure?
A Plastic and irrigation water
B Only mineral fertilizer granules
C Fresh leaves and sand
D Dung, urine, litter, crop residues
Answer: D. Dung, urine, litter, crop residues. Farmyard manure commonly includes livestock excreta mixed with bedding or litter and other organic residues.
How is compost generally produced?
A Decomposing organic materials
B Mixing water with urea
C Drying harvested grain
D Crushing mineral rock only
Answer: A. Decomposing organic materials. Compost is made by decomposition of organic materials under managed conditions.
What role do earthworms play in vermicomposting?
A Fix atmospheric nitrogen directly
B Replace all soil microbes
C Produce mineral phosphate
D Process organic materials
Answer: D. Process organic materials. Vermicomposting uses earthworms and microorganisms to process organic materials into a soil amendment.
When is a green-manure crop usually incorporated?
A Before seed germination
B After complete grain storage
C While it is still green
D Only after burning residues
Answer: C. While it is still green. Green manure is plant material grown and incorporated into soil, often before it becomes fully mature.
Why are legume crops often chosen for green manure?
A They can fix atmospheric nitrogen
B They prevent every weed
C They supply no organic matter
D They remove all soil carbon
Answer: A. They can fix atmospheric nitrogen. Legumes can host nitrogen-fixing bacteria and add biomass when incorporated.
What is a biofertilizer?
A A synthetic pesticide mixture
B A product with useful microorganisms
C A mineral fertilizer grade
D A seed storage container
Answer: B. A product with useful microorganisms. Biofertilizers contain living or dormant microorganisms that support nutrient availability or plant growth.
Which bacteria commonly form nitrogen-fixing nodules on legumes?
A Escherichia coli
B Rhizobium
C Bacillus thuringiensis
D Saccharomyces cerevisiae
Answer: B. Rhizobium. Rhizobium species commonly form symbiotic nodules on legume roots and fix atmospheric nitrogen.
How can mycorrhizal fungi help plant nutrition?
A Improve access to phosphorus
B Replace plant roots entirely
C Produce potassium fertilizer
D Create atmospheric oxygen
Answer: A. Improve access to phosphorus. Mycorrhizal associations can extend the effective soil volume explored by roots and improve phosphorus uptake.
Why combine organic and mineral nutrient sources?
A Make every field identical
B Remove need for soil tests
C Balance supply and soil benefits
D Stop all nutrient cycling
Answer: C. Balance supply and soil benefits. Integrated nutrient management combines sources to meet crop needs and support soil fertility.
What does balanced fertilization aim to provide?
A One dose for all crops
B Nitrogen alone at high rates
C Only nutrients already abundant
D Needed nutrients in balance
Answer: D. Needed nutrients in balance. Balanced fertilization supplies required nutrients in proportions suited to soil and crop needs.
Which test helps guide fertilizer rates for a field?
A Soil nutrient test
B Harvest moisture test
C Leaf counting only
D Seed color test
Answer: A. Soil nutrient test. Soil testing helps estimate nutrient status and guide locally recommended fertilizer decisions.
Why use crop-specific fertilizer recommendations?
A All crops remove identical nutrients
B Crop nutrient demand differs
C Soil conditions never vary
D Manure always has fixed composition
Answer: B. Crop nutrient demand differs. Crop nutrient demand varies by species, yield target, soil, and local production conditions.
Why can manure nutrient content vary from batch to batch?
A Soil pH sets its color
B Manure has a fixed grade
C Nutrients disappear at night
D Feedstock and handling differ
Answer: D. Feedstock and handling differ. Manure composition depends on source materials, moisture, storage, and handling.
Compared with soluble mineral fertilizer, how are nutrients from compost often released?
A Only after crop harvest
B Without microbial activity
C Gradually during decomposition
D All nutrients release instantly
Answer: C. Gradually during decomposition. Compost nutrient release depends on decomposition and is often gradual and variable.
How can organic matter benefit soil structure?
A Seal all soil pores
B Remove all soil organisms
C Improve aggregation and water retention
D Stop infiltration completely
Answer: C. Improve aggregation and water retention. Organic matter can support aggregation and increase the soil’s capacity to retain water.
What can fertilizer overapplication cause?
A Nutrient loss and plant injury
B No change to waterways
C Guaranteed higher yield
D Permanent soil improvement
Answer: A. Nutrient loss and plant injury. Excess fertilizer can injure crops, create nutrient imbalance, and increase losses to air or water.
Why split nitrogen applications in some crop systems?
A Replace the need for irrigation
B Match demand and limit losses
C Increase fertilizer caking
D Keep roots from absorbing nitrogen
Answer: B. Match demand and limit losses. Split applications can better match nitrogen supply to crop uptake and reduce losses in some systems.
How can placing fertilizer near active roots help?
A Eliminate soil testing
B Prevent all nutrient losses
C Change the crop variety
D Improve access to nutrients
Answer: D. Improve access to nutrients. Appropriate placement can improve nutrient access and reduce contact with areas where loss or fixation is likely.
Why should concentrated fertilizer avoid direct seed contact?
A It fixes soil acidity
B It changes seed genetics
C It prevents seed respiration
D It may injure emerging seedlings
Answer: D. It may injure emerging seedlings. High salt or ammonia concentrations near seed can damage germinating seeds and young roots.
Surface-applied urea can lose nitrogen as which gas under some conditions?
A Ammonia
B Methane only
C Hydrogen
D Oxygen
Answer: A. Ammonia. Surface urea can lose nitrogen through ammonia volatilization, especially under conditions that favor the process.
Nitrate can move below roots mainly through what process?
A Photosynthesis
B Pollination
C Leaching
D Seed scarification
Answer: C. Leaching. Nitrate is soluble and may move below the root zone with percolating water.
Excess phosphorus entering surface water can contribute to what?
A Root nodulation
B Eutrophication
C Seed dormancy
D Soil aeration
Answer: B. Eutrophication. Phosphorus enrichment of water can contribute to algal growth and eutrophication.
Why store bagged fertilizers in a dry covered area?
A Speed up decomposition
B Limit moisture uptake
C Raise seed germination
D Increase their nutrient grade
Answer: B. Limit moisture uptake. Moisture can cause caking and reduce handling or spreading quality.
What can moisture absorption cause in some fertilizers?
A Higher nutrient content
B Improved seed purity
C Caking and poor flow
D More uniform rainfall
Answer: C. Caking and poor flow. Moisture uptake can make fertilizer granules cake and flow poorly.
How does calibrating a fertilizer spreader help?
A Apply a more accurate rate
B Prevent rainfall losses
C Guarantee a fixed yield
D Remove nutrient deficiencies
Answer: A. Apply a more accurate rate. Calibration helps deliver a planned rate more consistently across the field.
What should farmers check on a fertilizer label?
A The seller’s address alone
B The crop’s harvest date
C Only the bag color
D Grade and nutrient content
Answer: D. Grade and nutrient content. The label identifies the product and its guaranteed nutrient grade or content.
What does foliar fertilizer application target?
A Only deep soil layers
B The seed storage bag
C Plant leaves
D The field drainage outlet
Answer: C. Plant leaves. Foliar feeding applies dissolved nutrients to leaf surfaces for uptake when appropriate.
How does fertigation deliver nutrients?
A Through harvest equipment
B Through irrigation water
C By burning crop residues
D By seed drying
Answer: B. Through irrigation water. Fertigation supplies dissolved nutrients through an irrigation system.
Why test manure before crediting its nutrients in a plan?
A Testing changes the manure
B Every crop needs equal amounts
C Manure contains no nutrients
D Its nutrient content varies
Answer: D. Its nutrient content varies. Manure nutrient content varies, so testing or reliable local estimates help avoid under- or over-application.
If manure is applied, what belongs in the field nutrient plan?
A Its available nutrient contribution
B Only its purchase price
C Its color and texture alone
D No nutrient credit
Answer: A. Its available nutrient contribution. Nutrients supplied by manure should be considered when planning additional fertilizer.
What does a nutrient budget compare?
A Nutrient inputs and removals
B Plant height and market price
C Rainfall and wind speed
D Seed color and field size
Answer: A. Nutrient inputs and removals. A nutrient budget accounts for nutrient sources entering a field and nutrients removed or lost.
Why turn an aerobic compost pile?
A Increase plastic content
B Stop decomposition
C Add oxygen and mix materials
D Remove all microorganisms
Answer: C. Add oxygen and mix materials. Turning can supply oxygen and mix materials during aerobic composting.
What does composting transform?
A Mineral fertilizer into seed
B Organic residues into stabilized material
C Water into nutrients
D Clay into sand
Answer: B. Organic residues into stabilized material. Composting biologically decomposes organic residues into a more stabilized material.
Which material can serve as green manure?
A A grain-only crop
B A mineral fertilizer granule
C A stored seed lot
D A crop grown for incorporation
Answer: D. A crop grown for incorporation. Green manure crops are grown mainly to add plant biomass and nutrients when incorporated.
What should a compatible inoculant provide to legume roots?
A A herbicide coating
B Nitrogen-fixing microorganisms
C A seed-coat treatment
D Mineral phosphorus granules
Answer: B. Nitrogen-fixing microorganisms. Legume inoculants may introduce compatible nitrogen-fixing bacteria to support nodulation.
Why can biofertilizers not always replace all mineral fertilizers?
A They contain no microorganisms
B They prevent root uptake
C They instantly supply every nutrient
D Their nutrient effects are specific
Answer: D. Their nutrient effects are specific. Biofertilizers support particular nutrient processes but do not automatically provide every nutrient a crop requires.
Why should fertilizer rates vary among fields?
A Soil and crop needs differ
B Fertilizer grades are identical
C All fields have equal fertility
D Weather never affects uptake
Answer: A. Soil and crop needs differ. Field-specific soil status, crop demand, and local conditions affect appropriate rates.
What influences nutrient release from manure?
A Farm boundary and road
B Seed size and flower color
C Moisture, temperature, microbes
D Bag color and label font
Answer: C. Moisture, temperature, microbes. Decomposition and nutrient release depend on factors including moisture, temperature, material quality, and microbial activity.
What is a key aim of integrated nutrient management?
A Replace crop rotation everywhere
B Use only synthetic fertilizers
C Combine sources for sustained fertility
D Ignore nutrient balances
Answer: C. Combine sources for sustained fertility. Integrated nutrient management combines suitable nutrient sources and practices to meet crop needs while maintaining soil fertility.
When source quality is uncertain, what can testing check?
A Potential contaminant levels
B Irrigation scheduling
C Seed germination rates
D Crop rotation sequence
Answer: A. Potential contaminant levels. Testing can assess contaminants in materials when the source or handling history raises a concern.