Skip to the content
Peabody TeachFor teachers and grown-ups

Peas, Beans, and the Nitrogen Trade

7th grade nonfiction passage about legumes and crop rotation: 246 words, six questions, an answer key and vocabulary.

7th grade nonfiction legumes and crop rotation 246 words

Peas, Beans, and the Nitrogen Trade

Plants need nitrogen the way people need food. It is a main ingredient in the proteins and green pigments that plants build as they grow. Air is mostly nitrogen, but plants cannot use it in that form. They must take it up from the soil, in chemical forms that roots can absorb. After a few seasons of growing the same crop, the soil on a farm can run low.

Peas, beans, lentils, peanuts, and clover belong to the legume family, and they have a remarkable partnership. On their roots, tiny bacteria move in and form small lumps called nodules. The bacteria take nitrogen from the air spaces in the soil and change it into a form the plant can use. In return, the plant feeds the bacteria with sugars made in its leaves. Both sides benefit, which scientists call a mutualism.

Farmers noticed long ago that fields did better after legumes. Many learned to practice crop rotation, planting different crops in a planned order across the years. A field might grow wheat one year, then clover or beans the next. When the legume plants die and decay, or are plowed under, some of the nitrogen they collected goes back to the soil, ready for the next crop.

Rotation also helps in other ways. It can interrupt the life cycles of insects and diseases that prefer a single crop. Because of these benefits, many farms still rotate their crops today, even though they can also buy fertilizer.

Questions

  1. Why can plants not use the nitrogen that is in the air? in the text

  2. What are nodules? in the text

  3. What does the plant give to the bacteria in return? in the text

  4. What is crop rotation? in the text

  5. Why might a farmer plant clover after a crop of wheat? think about it

  6. How can rotating crops help against insects that prefer one crop? think about it

Words to know

nitrogen
a gas in air that plants need to grow
legume
a plant family that includes peas and beans
nodules
small lumps on roots that hold helpful bacteria
mutualism
a partnership in which both sides gain
rotation
changing the crop in a field in a planned order
Share

One passage, three levels

The same topic and facts written three ways, so a mixed class can read and talk about one text. Each group’s sheet shows only a shape; the key says which is which.

● Easier · 187 words · Flesch-Kincaid grade 3.6

Plants need nitrogen to grow, just as people need food. Nitrogen is part of the proteins and green color in plants. The air is mostly nitrogen, but plants cannot use it from the air. They must get it from the soil through their roots. If a farmer grows the same crop for years, the soil can run low.

Peas, beans, lentils, peanuts, and clover are legumes. Legumes have a special partner. Tiny bacteria live on their roots in small lumps called nodules. The bacteria take nitrogen from the air in the soil. They change it into a kind the plant can use. The plant gives the bacteria sugar from its leaves. Both sides gain.

Farmers saw long ago that fields did better after legumes. So they use crop rotation. They plant different crops in a plan, year after year. A field might grow wheat one year and clover the next. When the legumes die, some nitrogen goes back into the soil for the next crop.

Rotation helps in other ways too. Insects and diseases that like one crop lose their food. Many farms still rotate crops today.

▲ This passage · 246 words · Flesch-Kincaid grade 6.7

Plants need nitrogen the way people need food. It is a main ingredient in the proteins and green pigments that plants build as they grow. Air is mostly nitrogen, but plants cannot use it in that form. They must take it up from the soil, in chemical forms that roots can absorb. After a few seasons of growing the same crop, the soil on a farm can run low.

Peas, beans, lentils, peanuts, and clover belong to the legume family, and they have a remarkable partnership. On their roots, tiny bacteria move in and form small lumps called nodules. The bacteria take nitrogen from the air spaces in the soil and change it into a form the plant can use. In return, the plant feeds the bacteria with sugars made in its leaves. Both sides benefit, which scientists call a mutualism.

Farmers noticed long ago that fields did better after legumes. Many learned to practice crop rotation, planting different crops in a planned order across the years. A field might grow wheat one year, then clover or beans the next. When the legume plants die and decay, or are plowed under, some of the nitrogen they collected goes back to the soil, ready for the next crop.

Rotation also helps in other ways. It can interrupt the life cycles of insects and diseases that prefer a single crop. Because of these benefits, many farms still rotate their crops today, even though they can also buy fertilizer.

■ Harder · 265 words · Flesch-Kincaid grade 10.1

Plants require nitrogen in much the same way that people require food, because it is a principal ingredient in the proteins and green pigments that plants manufacture as they grow. Although air is mostly nitrogen, plants cannot make use of it in that form. Instead they must absorb it through their roots from the soil, in chemical forms that dissolve readily, and after several seasons of growing a single crop, the soil on a farm can become depleted.

Peas, beans, lentils, peanuts, and clover all belong to the legume family, and they have formed a remarkable partnership. Tiny bacteria take up residence on their roots, where they create small lumps known as nodules. The bacteria capture nitrogen from the air spaces in the soil and convert it into a form the plant can use. In exchange, the plant nourishes the bacteria with sugars produced in its leaves. Because both partners benefit, scientists call the arrangement a mutualism.

Farmers observed long ago that fields performed better after legumes, and many learned to practice crop rotation, planting different crops in a planned order across the years. A field might grow wheat one year and then clover or beans the next. When the legume plants die and decay, or are plowed under, a portion of the nitrogen they gathered returns to the soil, ready for the following crop.

Rotation offers further advantages as well. It can disrupt the life cycles of insects and diseases that favor one particular crop. Because of these benefits, many farms continue to rotate their crops today, even though fertilizer is available for purchase.

Download as one PDF

How to use it

  1. Press Read it big (or B) to put the text on the projector, or Full screen (F) to fill the whole screen.
  2. Ask the questions one at a time and use Show answer when the class has decided. A shows or hides every answer.
  3. Print student copy for the class, or Print with answers for yourself.

Ideas for class

  • Before reading, put nitrogen, legume, nodules, mutualism and rotation on the board with their meanings from the Words to know section and have students predict what the text will be about.
  • Read it aloud once while students follow along, then have them reread it alone or with a partner. At a calm 100 words a minute it takes about 2 minutes to read aloud.
  • Use the Read it big button (or B) to put the text on the projector, and Show answer on one question at a time so the class commits to an answer first.
  • Question 5 asks the reader to infer. Ask students to point to the words in the passage that led them to their answer.
  • Ask students to write one question the passage did not answer, then look for the answer in a book or on a classroom screen.
  • Print the student copy for independent work and keep the answer-key copy for yourself.

Related

Questions

What reading level is "Peas, Beans, and the Nitrogen Trade"?

It was written for 7th grade. It has 246 words and works out to a Flesch-Kincaid grade level of about 6.7. That is a formula's estimate from sentence length and syllables, and it is not a Lexile or a guided reading level, so check it against your students.

What do the questions ask?

There are six. 4 ask for something the text says directly and 2 ask the reader to work something out from clues. Each has an answer in the key, and the answers are written as a teacher would accept them, not as the only possible wording.

How long does it take to read?

About 2 minutes read aloud at 100 words a minute. For a one-minute fluency check, paste it into the fluency timer and use the word count.

Can I print it?

Yes. Print student copy gives the passage, the questions with lines to write on, and the word meanings. Print with answers gives the same page with the answers filled in. Both are made in your browser.

Is this passage from a published book?

No. It was written for Peabody Teach, so there is no book to buy and no login to read it.

Nothing you do here is sent to us. No sign-in, no ads.