Video Transcript
Why is fertilizer A not as
effective as fertilizer B at promoting plant growth? (A) Fertilizer A does not contain
any sodium. (B) Fertilizer B inhibits seed
germination. (C) Fertilizer B only contains
nitrogen. (D) Fertilizer A does not contain
any phosphorous or potassium. (E) Fertilizer A raises the pH of
the soil. Fertilizer A is urea and fertilizer
B is an NPK fertilizer.
Fertilizers supply plants with
essential nutrients they need to grow. These essential nutrients are the
elements nitrogen, phosphorus, and potassium. That’s what this NPK in the NPK
fertilizer stands for, the atomic symbols of these three elements. So since fertilizer B is an NPK
fertilizer, it contains all of the essential nutrients we need to supply plants
through fertilization. If we look at fertilizer A, urea,
we can see that it does contain nitrogen, but it doesn’t contain phosphorous or
potassium. In this question, we’re looking for
the reason why fertilizer A is not as effective as fertilizer B. And what we just discussed about
the elements that each fertilizer contains probably has something to do with it.
But let’s take a look through our
answer choices. Answer choice (A) says that
fertilizer A does not contain any sodium. This statement is true. Fertilizer A doesn’t contain any
sodium, but neither does fertilizer B. That’s because sodium isn’t a
nutrient that we need to supply plants through fertilization. So this isn’t the correct
answer. Answer choice (B) says that
fertilizer B inhibits seed germination. Nitrogen-containing fertilizers do
inhibit seed germination. So you should take care not to
apply too much nitrogen-containing fertilizer too close to one seed to
germinate. But both fertilizer A and
fertilizer B contain nitrogen. So this isn’t correct either.
Answer choice (C) says that
fertilizer B contains only nitrogen. This statement is not true. Fertilizer B contains nitrogen,
phosphorus, and potassium because it’s an NPK fertilizer. Answer choice (D) says that
fertilizer A does not contain any phosphorous or potassium. This is true. Fertilizer A doesn’t contain any
phosphorous or potassium, which are two of the three essential nutrients that we
need to supply plants. So we found the correct answer. But let’s take a quick peek in
answer choice (E). This one says that fertilizer A
raises the pH of the soil. Fertilizer A, urea, does actually
change the soil pH. But it slightly lowers the pH of
the soil, not raises it. So, as we said, answer choice (D)
is the correct answer. Fertilizer A is not as effective as
fertilizer B because fertilizer A does not contain any phosphorous or potassium.
