Self-study
P1
As part of an international effort to address environmental problems resulting from agricultural overproduction, hundreds of thousands of acres of surplus farmland throughout Europe will be taken out of production in coming years. ███
Problem and Solution ·
Problem: overproduction / solution: let farms lie fallow
We're farming too hard and that's harming the environment. Solution is to let farms sit there and don't plant anything.
Problem Details ·
Too few nutrients; too much fertilizer
Farming depleted nutrients and introduced fertilizers. That makes it difficult to restore the land to "natural balance of flora." In particular, thistles (a weed) will crowd out other flora.
Impractical Solution ·
Remove and replace the topsoil
Impractical because we're not talking about my backyard garden. We're talking at the scale of hundreds of thousands of acres.
Potential Solution ·
Artificially accelerate recovery
Netherlands is doing a study to see if they can speed up natural recovery.
P2
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Experimental Setup ·
Control v. intervention groups
Two control groups: (C1) lie fallow and (C2) grow corn. Two intervention groups: (I1) grow mixture of native flora and (I2) grow native flora plus clover and toadflax.
Results ·
Intervention works
Both intervention groups forced out thistles (a weed). The fallow control group (C1) was overtaken by thistles.
P3
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Experiment setup ·
Another intervention group
(C3) grow mixture of native flora and mix in 20 years recovered soil. This intervention group is meant to test whether microorganisms in the soil would have beneficial effects.
Results ·
Intervention works
Flora grew better on the enriched plots.
Conclusion ·
Microorganisms in the soil are important for restoring natural flora
Researchers conclude (hypothesize with supporting evidence) that over farmed land contain too many disease organisms and too few beneficial organisms.
Solution ·
Sow beneficial microorganisms into soil
Passage Style
Problem-analysis
Single position
23.
Based on the passage, which ███ ██ ███ █████████ ██ ████ ██████ ██ ██ ████ ██ ███ ████ ████ ██ ███████ ███████ ██ ███ ███████ █████████ ██ ███ █████ ██████████
a
Thistles cannot grow ██ ███
“Cannot” is too strong. We have no reason to think thistles “cannot” grow in the soil. Perhaps thistles are less likely to grow in the replacement toil, but “cannot” goes too far.
b
It does not ███████ ███████████ ███████ ██ ██████
Fungi aren’t mentioned in connection with the topsoil replacement process in P1, so we don’t know whether the soil is likely to have fungi or not.
c
It contains very ███ █████ ██ ██████ ███████ ███ ██████
We have no reason to think the replacement soil contains “very few” seeds of native plants. Part of the reason for replacing heavily fertilized soil is to encourage native plants to reestablish themselves. So there’s some reason that the soil might have more than just “very few” seeds of native plants.
d
It does not ███████ █████ ███████ ██ ███████████
This is supported, because the process is designed to “restore” land that has been heavily fertilized. It wouldn’t make sense for the topsoil to be replaced with soil that contains large amounts of fertilizer, because over-fertilized land is the problem that the process is trying to solve.
e
It was never ████ ███ ███████ ████ ██ █████ ██████████ ██████
We have no reason to think the soil was “never” used for growing commercial crops. There is reason to think the replacement soil isn’t as heavily fertilized as the soil that it’s replacing, but that doesn’t imply it was never used for growing commercial crops.