Why did farmers let some fields lie fallow?

a.
to reduce the surplus of crops

b.
to bring new land under cultivation

c.
to increase the soil's productivity

d.
to allow serfs to grow their own food

Farmers let some fields lie fallow to increase the soil's productivity.

Option C

Explanation:

The farmers allow some fields to be fallow for the benefit of the soil. It is known that some farmers of the modern period allow fields to rest (fallow) from time to time. The rotation of crops has been an added contribution to the increase of productivity in the process of replacing fallow periods by planting and growing different cross that will enrich the soil by reproducing nutrients that benefit it.

Crops when grown and raised, are grown in form of receiving nutrients in the soil, by leaving it fallow allows the soil to rest in order for the nutrients to be reproduced.

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