The correct answer is (A).
Restoring Europe's Farmland
Step 1: Read the Passage Strategically
Sample Highlighting
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. Restoring a natural balance of flora to this land will be difficult, however, because the nutrients in soil that has been in constant agricultural use are depleted. Moreover, much of this land has been heavily fertilized, and when such land is left unplanted, problem weeds like thistles often proliferate, preventing many native plants from establishing themselves. While the quickest way to restore heavily fertilized land is to remove and replace the topsoil, this is impractical on a large scale such as that of the European effort. And while it is generally believed that damaged ecological systems will restore themselves very gradually over time, a study underway in the Netherlands is investigating the possibility of artificially accelerating the processes through which nature slowly reestablishes plant diversity on previously farmed land.
In the study, a former cornfield was raked to get rid of cornstalks and weeds, then divided into 20 plots of roughly equal size. Control plots were replanted with corn or sown with nothing at all. The remaining plots were divided into two groups: plots in one group were sown with a mixture of native grasses and herbs; those in the other group received the same mixture of grasses and herbs together with clover and toadflax. After three years, thistles have been forced out of the plots where the broadest variety of species was sown and have also disappeared from mats of grass in the plots sown with fewer seed varieties. On the control plots that were left untouched, thistles have become dominant.
On some of the plots sown with seeds of native plant species, soil from nearby land that had been taken out of production 20 years earlier was scattered to see what effect introducing nematodes, fungi, and other beneficial microorganisms associated with later stages of natural soil development might have on the process of native plant repopulation. The seeds sown on these enriched plots have fared better than seeds sown on the unenriched plots, but still not as well as those growing naturally on the nearby land. Researchers have concluded that this is because fields farmed for many years are overrun with aggressive disease organisms, while, for example, beneficial mycorrhiza—fungi that live symbiotically on plant roots and strengthen them against the effects of disease organisms—are lacking. These preliminary results suggest that restoring natural plant diversity to overfarmed land hinges on restoring a natural balance of microorganisms in the soil. In other words, diversity underground fosters diversity aboveground. Researchers now believe that both kinds of diversity can be restored more quickly to damaged land if beneficial microorganisms are "sown" systematically into the soil along with a wide variety of native plant seeds.
Passage Notes
Paragraph 1
Restoring land damaged by farming is difficult
Will restore naturally, but study investigating how to accelerate process artificially
Paragraph 2
Study methods
Results
Paragraph 3
Adding beneficial microorg
Why microorg helpful
Planting seeds and "sowing" in microorg is key to boosting diversity.
Discussion
In paragraph 1, the author introduces the Topic: farmland in Europe; and quickly narrows to Scope: problems with overproduction of that land. One problem in particular captures the author's attention: How can we restore a natural balance of flora to land that has been overworked? The second and third sentences of paragraph 1 detail some difficulties in solving this problem: The land has been stripped of nutrients, highly fertilized, and overrun by thistles. The author then goes on to present a quick solution (removing and replacing the topsoil), but tells you that this solution isn't practical. By the end of the paragraph, the author mentions that a study is underway to determine whether humans can accelerate the process of reestablishing biodiversity on this land.
Paragraph 2 describes the study's methodology—a former cornfield was divided into identical plots, some control and some variable—and gives some initial results three years into the study. On control plots, thistles dominated. On plots where a diverse set of flora was sown, thistles disappeared.
Paragraph 3 continues to detail the results of the study. Some of the plots of land were enriched with beneficial microorganisms, and those plots better supported seedlings than did plots that were not enriched. The third sentence of paragraph 3 introduces an explanation for this: Land farmed for many years contains a lot of harmful organisms and not very many beneficial organisms. This explanation leads to the author's ultimate recommendation: The sowing of native plant seeds should be accompanied by the introduction of beneficial microorganisms into the soil. This recommendation reveals the author's Purpose: to lay out a strategy for restoring a natural balance to overworked farmland; and Main Idea: natural balance can be restored by introducing both native seeds and beneficial microorganisms to damaged land.
(A) Global
Step 2: Identify the Question Type
The "central idea" of the passage is equivalent to its Main Idea, making this a Global question.
Step 3: Research the Relevant Text
With no specific sentences to research, use your Roadmap and the Topic, Scope, Purpose, and Main Idea summaries you made during Step 1.
Step 4: Make a Prediction
You already predicted the Main Idea during Step 1. The right answer may use slightly different words, but it will express the same idea: that sowing native seeds and helpful microorganisms simultaneously could be a viable way to restore farmland.
Step 5: Evaluate the Answer Choices
(A) matches this prediction. The term "two-pronged" clearly refers to using native seeds and beneficial microorganisms simultaneously.
(B) is too general and misrepresents the study, which achieved a favorable balance of flora in the damaged farmland after only three years.
(C) is Outside the Scope. The author never argues for a change in farming practices. The passage focuses only on how to recover the original biodiversity of the farmland.
(D) blows up a small point made at the end of paragraph 1 and tries to pass it off as the main idea of the passage. If (D) were the author's main point, there would be no need to discuss the study and its implications.
(E) ignores the author's focus on possible solutions to reestablish natural diversity in farmland.
