AP Environmental Science : Soil Problems and Solutions
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Example Questions
Example Question #1 : Soil Problems And Solutions
Soil with insufficient nitrogen is generally easier to fix than soil insufficient in phosphorus. Why might this be?
Atmospheric phosphorus disperses in the form of precipitation, and irrigating crops from a well source will be insufficient in replenishing phosphorus to the soil.
Phosphorus is generally scarce in the natural world.
Nitrogen is abundant in the soil and the atmosphere, while phosphorus is only available in the soil and in bedrock.
There are significantly more steps in the phosphorus cycle to make phosphorus usable for plants, limiting availability.
Many plants are incapable of taking up available phosphorus, making it very difficult to have compost that is rich in phosphorus.
Nitrogen is abundant in the soil and the atmosphere, while phosphorus is only available in the soil and in bedrock.
There is a sizable bank of nitrogen in the atmosphere that can be fixed by certain bacteria (and plants that harbor this bacteria in their roots), while phosphorus originates largely from bedrock and is released into the soil in limited quantities. Nitrogen can be fixed from a collective atmosphere that is three-quarters nitrogen, while phosphorus is more region-specific and can be harder to replace than nitrogen once it's depleted. Farms located in phosphorus-poor regions often have to rely on mined phosphates.
Example Question #2 : Soil Problems And Solutions
Phosphorus is an essential nutrient for all plants, including the ones we grow to eat. If a farmer faces the challenge of phosphorus-poor soil, what can they do to remedy the problem.
Move the farm elsewhere. Once phosphorus is gone, it's gone.
Deep-till the soil, bringing up phosphorus-rich soil and rock fragments from the subsoil layers.
Plant phosphorus-fixing cover crops to increase phosphorus presence in soil.
Spread manure and then mulch to prevent leaching or erosion of nutrients.
Apply a substantial layer of chemical nitrates to the soil.
Spread manure and then mulch to prevent leaching or erosion of nutrients.
Phosphorus defficiency is a challenge to resolve because phosphorus stores are almost exclusively in bedrock and sediment, and there is only as much as the bedrock weathers over time. Manure is very rich in phosphorus, and since plants do not fix phosphorus directly into the soil, applying manure and then covering with mulch is the best option.
Example Question #3 : Soil Problems And Solutions
Which of the following would be the most accurate example of sheet erosion?
A farmer employs flood irrigation on a field with a slope, causing thin layers of soil to wash away over time.
Soil is lost from irrigation ditches, causing the ditch to become wider and deeper.
Wide channels develop in the soil where a stormwater discharge site has been established.
Light rain falls on a farmer's field that is mostly bare soil.
Narrow channels develop in a farmer's field from running irrigation lines over exposed soil.
A farmer employs flood irrigation on a field with a slope, causing thin layers of soil to wash away over time.
Sheet erosion occurs when either wind or widespread shallow water with a slow current degrades the soil in thin layers. A flooded and uneven field that is mostly bare soil will likely experience sheet erosion because the erosion is shallow and uniform.
Example Question #4 : Soil Problems And Solutions
Climate change has increased the variability in weather patterns. Unpredictable weather patterns are hard to manage. In 2015, heavy rainfall events caused farm field soils in Ohio to become saturated with water. This killed off many farmers' crops because the plants couldn't receive carbon dioxide/oxygen due to all the water. What is this phenomenon called?
Rill erosion
Waterlogging
Sheet erosion
Salinization
Gully erosion
Waterlogging
The correct response is waterlogging. In waterlogging, water covers plant roots and soils with water - preventing soils from absorbing oxygen from the air. If the water covers the soil surface for too long, plants begin to die because their roots can't absorb oxygen and/or carbon dioxide from the atmosphere in order to undergo respiration. Salinization involves the increase in salt content of soil. Sheet erosion is the process by which thin layers of soil are moved due to the force of rain drops and overland flow. Gully erosion involves the formation of gullies (small valleys) due to intensive erosion by water. Rill erosion involves water creating rills, small channels through which water flows.
Example Question #5 : Soil Problems And Solutions
Farmers use a variety of techniques to conserve soil nutrient quality. Which of the following is not a soil conservation technique?
Contour plowing
Add legumes
Intensification
Cover crops
Intensification
The correct response is intensification. The term intensification refers to farmers working the fields more heavily and intensely. All the other responses are techniques used by farmers to conserve soil.
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