Liberal Arts Blog — Legumes: Root Nodules, Green Manure, Crop Rotation, Ben Franklin, Henry Ford

Liberal Arts Blog — Wednesday is the Joy of Science, Engineering, and Technology Day

Today’s Topic — Legumes: Root Nodules, Green Manure, Crop Rotation, Ben Franklin, Henry Ford

Have you said a prayer of thanks for legumes lately? They really are little miracles. “Within legume root nodules, nitrogen gas (N2) from the atmosphere is converted into ammonia (NH3), which is then assimilated into amino acids (the building blocks of proteins) nucleotides (the building blocks of DNA and RNA as well as the important energy molecule ATP), and other cellular constituents such as vitamins, flavones, and hormones. Their ability to fix gaseous nitrogen makes legumes an ideal agricultural organism as their requirement for nitrogen fertilizer is reduced. Indeed, high nitrogen content blocks nodule development as there is no benefit for the plant from forming the symbiosis. The energy for splitting the nitrogen gas in the nodule comes from sugar that is translocated from the leaf (a product of photosynthesis.” Today, a few more notes. Experts — please chime in. Correct, elaborate, elucidate.

A BIT OF HISTORY: from the Indus Valley and China to Ben Franklin and Henry Ford

1. Evidence of legume cultivation goes back to 3300 BC in the Ravi River region of the Punjab.

2. “The soybean was first domesticated around 5,000 years ago in China from a descendant of the wild vine Glycine soja.”

3. “In the United States, the domesticated soybean was introduced in 1770 by Benjamin Franklin, after he sent seeds to Philadelphia from France.”

NB: Henry Ford, a vegetarian, was the first person to use soybeans for large-scale industrial purposes.”


1.“When a legume plant dies in the field, for example following the harvest, all of its remaining nitrogen incorporated into amino acids inside the remaining plant parts, is released back into the soil. In the soil, the amino acids are converted to nitrate (NO-3), making the nitrogen available to other plants, thereby serving as fertilizer for future crops.”

2. “In many traditional and organic farming practices, crop rotation with legumes is common. By alternating between legumes and non-legumes, sometimes planting legumes two times in a row and then legumes, the field usually receives enough nitrogenous compounds to produce a good result even when the crop is non-leguminous. Legumes are sometimes referred to as “green manure.”

3. “When used as a dry grain, the seed is also called a pulse…The FAO notes that the term “pulses” is limited to legumes harvested solely for dry grain, thereby excluding legumes that are harvested green for food (green peas, green beans, etc.) which are classified as vegetable crops. Also excluded are those legumes used mainly for oil extraction (e.g., soybeans and groundnuts) or used exclusively for sowing purposes (e.g., seeds of clover and alfalfa).”

NB: “Legume species grown for their flowers include lupins, which are farmed commercially for their blooms as well as being popular in gardens worldwide.” (see below)

Root nodule — Wikipedia


PDF with headlines — Google Drive


#1 A graphic guide to justice (9 metaphors on one page).

#2 “39 Songs, Prayers, and Poems: the Keys to the Hearts of Seven Billion People” — Adams House Senior Common Room Presentation, 11/17/20


Please share the coolest thing you learned this week related to science, engineering, or technology. Or, even better, the coolest or most important thing you learned in your life related to science and engineering.

This is your chance to make someone else’s day. Or to cement in your mind something that you might otherwise forget. Or to think more deeply about something dear to your heart. Continuity is key to depth of thought.



Passionate about education, thinking citizenship, art, and passing bits on of wisdom of a long lifetime.

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John Muresianu

Passionate about education, thinking citizenship, art, and passing bits on of wisdom of a long lifetime.