AP Environmental Science Quiz: Sustainable Agriculture

What this quiz covers

This quiz focuses on Sustainable Agriculture, giving you a quick way to practice the rules, question types, and explanations that matter most for AP Environmental Science.

How to use this quiz

Try each quiz question before looking at the correct answer. Use the explanations to review missed ideas, then come back to similar questions until the pattern feels familiar.

Question 1

1. Increase evaporation by irrigating during the hottest hours so salts crystallize and can be harvested easily.
2. Improve drainage and periodically leach salts with appropriate-quality water to move salts below root zones. (correct answer)
3. Stop all irrigation permanently, because salts will dissolve and leave the soil through plant uptake.
4. Add more sodium-based fertilizers so plants acclimate to salts and maintain yields without changes.

Explanation: Soil salinity from irrigation can be mitigated by improving drainage to prevent waterlogging and leaching salts with low-salt water. This moves salts below root zones, restoring productivity. Sustainability involves monitoring water quality and soil conditions. Unlike stopping irrigation or adding more salts, leaching addresses the root cause. Compacting soil would worsen issues. Proper management prevents long-term land degradation.

Question 2

1. Intercropping/cover cropping that can reduce erosion, suppress weeds, and add nitrogen if legumes are used. (correct answer)
2. Clear-cutting that increases albedo and reduces evapotranspiration by eliminating understory vegetation.
3. Slash-and-burn agriculture that increases soil fertility primarily through long‑term charcoal formation.
4. Hydroponics, since plants grown between rows are not rooted in soil and rely on nutrient solutions.

Explanation: Planting clover between orchard rows is an example of intercropping or cover cropping, which enhances sustainability in agroecosystems. Clover, a legume, fixes nitrogen through symbiotic bacteria, reducing the need for synthetic fertilizers. It also suppresses weeds, reduces erosion by covering soil, and improves soil structure with its root system. This practice supports biodiversity, attracting pollinators and beneficial insects to the orchard. In sustainable farming, such polycultural approaches mimic natural systems, promoting resilience and resource efficiency. Over time, this can lead to healthier soils and more stable yields without excessive inputs.

Question 3

1. Soil test results and crop nutrient requirements to match application rates and timing with plant uptake. (correct answer)
2. The maximum fertilizer rate affordable, since economic optimization always minimizes environmental impacts.
3. Distance to the nearest ocean, because coastal proximity determines nitrogen transformations in soil.
4. Average wind speed only, since nutrient losses occur primarily through wind transport of dissolved ions.

Explanation: Nutrient management plans optimize fertilizer use to meet crop needs without excess. Soil tests reveal current nutrient levels, while crop requirements guide precise applications. Timing aligns with uptake periods to minimize losses like leaching. Sustainable agriculture uses these metrics for efficient, environmentally sound practices. This prevents pollution and conserves resources. Regular updates ensure adaptive, effective planning.

Question 4

1. Raising carnivorous fish with large inputs of wild-caught fishmeal, increasing pressure on ocean fisheries.
2. Using integrated multi-trophic aquaculture where waste from one species becomes nutrients for another. (correct answer)
3. Discharging untreated effluent directly into coastal waters to dilute nutrients and prevent local impacts.
4. Stocking ponds at maximum density without monitoring disease to maximize short‑term production.

Explanation: Integrated multi-trophic aquaculture recycles waste as nutrients between species, reducing pollution and resource use. This mimics natural ecosystems for sustainability. Unlike relying on wild fishmeal or discharging effluent, it minimizes impacts. High-density stocking without monitoring risks disease. Avoiding mangrove clearance preserves habitats. The practice supports efficient, eco-friendly protein production.

Question 5

1. Mycorrhizal fungi that convert nitrate into atmospheric nitrogen gas during aerobic respiration.
2. Rhizobium bacteria in legume root nodules that convert $N_2$ into ammonia usable by plants. (correct answer)
3. Earthworms that synthesize nitrogen from carbon dioxide and water during digestion of residues.
4. Termites that oxidize ammonia into nitrate in their gut, creating new nitrogen for ecosystems.

Explanation: Biological nitrogen fixation converts atmospheric nitrogen into plant-usable forms through symbiotic relationships. Rhizobium bacteria in legume root nodules perform this process, producing ammonia that benefits the host plant. This reduces reliance on synthetic fertilizers, lowering costs and environmental impacts. Sustainable farming incorporates legumes in rotations or intercropping to enhance soil nitrogen naturally. The fixed nitrogen also benefits subsequent crops, promoting fertility cycles. Overall, leveraging such biological processes supports eco-friendly nutrient management.

Question 6

1. Growing a single crop species over thousands of hectares with uniform irrigation to maximize mechanization efficiency.
2. Integrating rows of trees with crops or livestock to enhance biodiversity, reduce erosion, and diversify income. (correct answer)
3. Removing all trees from farmland to reduce shading and increase photosynthesis in annual crops.
4. Applying synthetic nitrogen annually to maintain high yields regardless of soil organic matter trends.

Explanation: Agroforestry integrates trees with crops or livestock, creating diverse systems that enhance biodiversity and soil protection. Trees reduce erosion, provide windbreaks, and offer additional income from fruits or timber. This practice improves sustainability by mimicking natural ecosystems and diversifying farm outputs. Unlike monocultures or removing trees, which degrade land, agroforestry builds resilience. It contrasts with paved feedlots or heavy synthetic inputs, which increase environmental burdens. The integration supports long-term productivity and ecosystem services.

Question 7

1. Increased fossil-fuel production through higher soil petroleum formation in aerobic surface horizons.
2. Pollination and biological pest control by supporting pollinators and natural enemies of crop pests. (correct answer)
3. Ocean alkalinity regulation by increasing carbonate deposition in terrestrial soils.
4. Ozone layer repair by increasing plant respiration and releasing oxygen directly into the stratosphere.

Explanation: Diverse flowering strips attract pollinators and beneficial insects, enhancing pollination and natural pest control. This ecosystem service supports crop yields without additional inputs. Sustainability is improved by fostering biodiversity and reducing pesticide needs. Unlike unrelated services like fossil-fuel production or ozone repair, this directly aids agriculture. It doesn't increase salinity tolerance but promotes ecological balance. The practice integrates wildlife into farming systems effectively.

Question 8

1. Flood irrigation, because it saturates the entire field and eliminates evaporation from exposed soil surfaces.
2. Center-pivot sprinklers at midday, because higher temperatures increase droplet penetration into soil.
3. Drip irrigation, because water is delivered directly to roots with reduced evaporation and runoff. (correct answer)
4. Open-channel irrigation, because unlined canals recharge aquifers without any water losses.

Explanation: Drip irrigation delivers water directly to plant roots through tubes, minimizing evaporation and runoff losses. This efficiency is crucial in arid regions, using less water per yield compared to flood or sprinkler methods. It promotes sustainability by conserving water resources and reducing energy for pumping. Unlike flood irrigation, which wastes water through surface evaporation, drip targets delivery precisely. Overhead misting or open channels often lead to higher losses. The method also helps prevent soil salinization by avoiding overwatering.

Question 9

1. Terraces increase slope length and water velocity, improving drainage and preventing waterlogging.
2. Terraces reduce erosion by creating level steps that slow runoff and allow more infiltration. (correct answer)
3. Terraces increase salinity by trapping seawater aerosols and concentrating salts in flat benches.
4. Terraces eliminate the need for soil conservation because they prevent any rainfall from reaching soil.

Explanation: Terracing transforms steep slopes into a series of level steps, which is a time-tested sustainable method to combat erosion in hilly terrains. By shortening slope lengths, terraces slow runoff velocity, allowing more water to infiltrate the soil rather than carrying away topsoil. This reduces soil loss, preserves fertility, and can improve water retention for crops. In sustainable agriculture, terracing is often combined with contour planting or agroforestry to enhance stability and biodiversity. The practice has been used globally, from ancient rice paddies to modern vineyards, demonstrating its long-term benefits. Ultimately, terracing supports resilient farming systems that maintain productivity on challenging landscapes.

Question 10

1. Channelize streams to increase flow velocity and transport sediments downstream away from farmland.
2. Maintain ground cover and use buffer strips to trap sediment before it reaches waterways. (correct answer)
3. Increase tillage to break soil clods into finer particles that settle faster in streams.
4. Apply fertilizer after storms to replace nutrients lost with sediment, restoring stream clarity.

Explanation: Sediment from farms can degrade stream quality by increasing turbidity and harming aquatic life. Maintaining ground cover reduces soil detachment, while buffer strips trap particles before entry. This filters runoff naturally, improving water clarity. Sustainable agriculture emphasizes vegetative barriers for protection. They also support biodiversity and nutrient uptake. Such practices ensure cleaner waterways and compliant farming.

Question 11

1. Plant the same crop annually and rely on a single herbicide to simplify management and reduce labor.
2. Use cover crops and crop rotation to suppress weeds and break weed life cycles, reducing chemical dependence. (correct answer)
3. Remove all crop residues so weeds have less competition and can be identified more easily.
4. Irrigate more frequently to encourage weed germination, then allow weeds to outcompete pests.

Explanation: Weed management in sustainable agriculture seeks to minimize herbicide use while controlling competition. Cover crops and crop rotation disrupt weed life cycles, suppress growth, and improve soil health. This reduces chemical dependence and prevents resistance development. Diversification fosters natural suppression through competition and allelopathy. Farmers can integrate mechanical methods for comprehensive control. Overall, these strategies promote resilient, low-input systems.

Question 12

1. Apply fertilizer immediately before heavy rain so nutrients dissolve quickly and move into soil profiles.
2. Install vegetated riparian buffer strips along waterways to trap sediments and absorb excess nitrogen and phosphorus. (correct answer)
3. Replace crop diversity with monoculture to simplify management and reduce the number of fertilizer applications.
4. Increase field drainage tiles to move water off fields faster, preventing any nutrient transport to streams.

Explanation: Nutrient runoff from farms can lead to eutrophication in downstream waters, causing algal blooms and oxygen depletion. Vegetated riparian buffers act as filters, trapping sediments and absorbing excess nutrients like nitrogen and phosphorus before they reach waterways. This practice enhances sustainability by protecting water quality and supporting wildlife habitats. Unlike applying fertilizer before rain, which increases runoff, or burning residues, which adds no protection, buffers are effective barriers. Increasing drainage tiles might speed water movement but often exacerbates nutrient transport without filtration.

Question 13

1. Wetlands increase runoff speed so sediments are carried away quickly and do not accumulate on farmland.
2. Wetlands slow water flow, allowing sedimentation and nutrient uptake/denitrification that reduces pollution. (correct answer)
3. Wetlands sterilize water by increasing UV radiation exposure through reflective plant surfaces.
4. Wetlands convert nitrate directly into phosphorus fertilizer, increasing downstream productivity safely.

Explanation: Constructed wetlands are engineered systems that mimic natural wetlands to treat agricultural runoff by filtering pollutants. The primary mechanism involves slowing water flow, which allows sediments to settle and plants/microbes to uptake nutrients like nitrogen and phosphorus. Denitrification, a microbial process, converts nitrate into harmless nitrogen gas, reducing eutrophication risks downstream. This sustainable practice enhances water quality without relying on chemical treatments, supporting biodiversity in the wetland itself. Farmers can integrate wetlands into their operations to comply with regulations and promote ecosystem services. Overall, such nature-based solutions exemplify how sustainable agriculture balances production with environmental protection.

Question 14

1. It channels water downhill more efficiently, increasing runoff velocity and transporting more topsoil.
2. It reduces runoff and erosion by following elevation contours, slowing water flow across the slope. (correct answer)
3. It increases soil salinity by trapping salts in furrows aligned with the slope's steepest gradient.
4. It prevents nutrient uptake by compacting soil layers, reducing root penetration and water storage.

Explanation: Contour plowing follows land contours, creating ridges that slow water flow and reduce erosion on slopes. This prevents runoff from gaining speed and carrying away soil. Sustainability benefits include soil conservation and better water infiltration. Unlike plowing downhill, which accelerates erosion, contouring protects landscapes. It doesn't increase salinity or compact soils. The practice is essential for hilly terrain farming.

Question 15

1. More bare soil patches appear because livestock concentrate grazing, increasing erosion and decreasing infiltration.
2. Vegetation recovers between grazing periods, improving ground cover, soil structure, and reducing runoff. (correct answer)
3. Cattle remain on the same pasture year-round, minimizing labor and maximizing forage consumption efficiency.
4. Streambank trampling increases because animals are encouraged to access waterways more frequently for drinking.

Explanation: Rotational grazing involves moving livestock between paddocks, allowing vegetation in rested areas to recover and regrow. This improves ground cover, enhances soil structure through better root development, and reduces runoff and erosion. It prevents overgrazing in any single area, maintaining pasture health and biodiversity. Sustainability is improved as it mimics natural grazing patterns, leading to healthier ecosystems. Unlike continuous grazing, which can lead to bare patches and compaction, rotation minimizes negative impacts. Methane emissions may decrease due to better forage quality, but not to zero, making recovery of vegetation the key indicator.

Question 16

1. Apply pesticides on a fixed calendar schedule regardless of pest monitoring to prevent any possible infestation.
2. Use pest scouting and economic thresholds, then combine biological controls and targeted pesticides only when needed. (correct answer)
3. Eliminate all non-crop vegetation to remove habitat, even if it increases erosion and reduces pollinator populations.
4. Rely exclusively on a single pesticide class to reduce costs and simplify application decisions.

Explanation: Integrated Pest Management (IPM) emphasizes monitoring pests and using a combination of methods to control them only when necessary, based on economic thresholds. This includes biological controls like beneficial insects and targeted pesticides, reducing overall chemical use. IPM promotes sustainability by minimizing environmental impact and preventing pest resistance. Unlike fixed-schedule applications or eliminating all vegetation, IPM is adaptive and holistic. It avoids reliance on single methods, which can lead to imbalances. This approach maintains crop yields while protecting ecosystems.

Question 17

1. Leave the field bare to allow soils to dry and harden, preventing detachment by raindrop impact.
2. Plant a winter cover crop to keep soil covered and anchored by roots during heavy precipitation. (correct answer)
3. Deep plow immediately after harvest to bury residues and expose fresh soil for faster nutrient mineralization.
4. Remove remaining residues for biofuel feedstock, maximizing soil exposure to sunlight and warming.

Explanation: Post-harvest fields are vulnerable to erosion from winter storms without protective cover. Planting winter cover crops maintains soil coverage and root anchorage, reducing detachment and transport. This also captures nutrients and builds organic matter. Sustainable methods like this prevent bare soil exposure. They enhance resilience to weather extremes. Integrating with no-till further amplifies benefits.

Question 18

1. Use the same pesticide repeatedly because consistent selection pressure prevents resistant individuals from surviving.
2. Rotate pesticide modes of action and integrate nonchemical controls to reduce consistent selection for resistance. (correct answer)
3. Apply pesticides at lower-than-labeled doses so pests adapt slowly and remain partially susceptible.
4. Eliminate refuges of untreated pests, ensuring all individuals are exposed and resistance cannot spread.

Explanation: Rotating pesticide modes and integrating nonchemical controls varies selection pressure, slowing resistance evolution in pests. This maintains pesticide efficacy over time. Sustainability benefits from reduced chemical reliance and monitoring. Unlike repeated use or low doses, rotation manages resistance effectively. Eliminating refuges can accelerate resistance. The strategy supports long-term pest management.

Question 19

1. Store manure in unlined lagoons near streams to reduce hauling costs and encourage natural dilution.
2. Install anaerobic digesters to capture methane for energy and reduce odors and pathogen loads in manure. (correct answer)
3. Increase prophylactic antibiotic use to maximize growth rates, regardless of resistance concerns.
4. Increase stocking density to reduce land use per animal, even if waste management becomes more difficult.

Explanation: Confined animal feeding operations (CAFOs) generate large volumes of manure, leading to challenges like greenhouse gas emissions, odors, and water pollution. Installing anaerobic digesters captures methane from manure decomposition, converting it into renewable energy while reducing emissions. This process also lowers pathogen levels and produces nutrient-rich digestate for use as fertilizer. Sustainable livestock management emphasizes waste-to-resource strategies to minimize environmental footprints. By adopting digesters, CAFOs can improve air and water quality, comply with regulations, and potentially generate income from energy sales. Such innovations align with broader goals of circular agriculture, where waste becomes a valuable input.

Question 20

1. Perennial grains require more annual plowing, which increases soil disturbance and reduces erosion.
2. Perennial root systems can reduce erosion and nutrient leaching by keeping soil covered year-round. (correct answer)
3. Perennials eliminate the need for any water because deep roots create water through respiration.
4. Perennial crops always increase pesticide use because they host pests continuously with no management options.

Explanation: Perennial grains maintain year-round root systems and cover, reducing erosion and nutrient leaching compared to annuals. This builds soil health and sequesters carbon. Sustainability benefits include less tillage and water use. Unlike increasing pesticides or eliminating water needs, perennials offer natural advantages. They don't stop microbial activity but enhance ecosystems. The transition supports resilient farming.