Soil scientists studying the role of compost in horticulture have foun

I believe B is the correct answer.

The discrepancy highlighted in the passage is that (1) soil scientists find that compost does not have sufficient nutrients to replace fertilizers while (2) home gardeners find that compost works perfectly well for them without fertilisers even though the soil lacked essential nutrients. Option B is able to resolve this discrepancy, since the different composts used will contain different materials and consequently the nutrients that it provides to the plants.


Soil scientists studying the role of compost in horticulture have found that, while compost is useful for building soil structure, it does not supply large enough quantities of the nutrients essential for plant growth to make it a replacement for fertilizer. Many home gardeners, however, have found they can grow healthy and highly productive plants in soil that lacked essential nutrients by enriching the soil with nothing but compost.

Which one of the following, if true, most helps to explain the discrepant findings of the soil scientists and the home gardeners?


(A) The findings of soil scientists who are employed by fertilizer manufacturers do not differ widely from those of scientists employed by the government or by universities.

(B) Compost used in research projects is usually made from leaves and grass clippings only, whereas compost used in home gardens is generally made from a wide variety of ingredients.

(C) Most plants grown in home gardens and in scientists’ test plots need a favorable soil structure, as well as essential nutrients, in order to thrive.

(D) The soil in test plots, before it is adjusted in the course of experiments, tends to contain about the same quantities of plant nutrients as does soil in home gardens to which no compost or fertilizer has been added.

(E) Some of the varieties of plants grown by home gardeners require greater quantities of nutrients in order to be healthy than do the varieties of plants generally grown by the soil scientists in test plots.

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