Production of Food and its Management — BIOLOGY STD 8 — Question
ICSE BoardEnglish MediumSTD 8BIOLOGYProduction of Food and its Management3 Marks
Question
Describe the various natural methods of replenishing soil.
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Answer
$a.$ Field fallow : One way of allowing land to regain the nutrients naturally is to leave it free $($or fallow$)$ for one or more*Reasons, Dead plants, animals and other organic matter that collect on the land are decomposed by microbes. Thus, the nutrients are returned,to the soil.
$b.$ Crop rotation : Each crop uses more of some nutrients and less of others. Farmers, therefore, change their crop in each season so that the soil is not depleted of any particular nutrient. This practice of growing crop is called crop rotation. For example, wheat and rice use up large amounts of nitrogen from the soil. This nitrogen can be naturally replenished if the next crop grown is that of a legume, like pea and groundnut. Leguminous crops use nitrogen of the air to make nitrates, which replenish the soil with usable nitrogen. The soil is then ready for the next wheat or rice crop.
$c.$ Mixed cropping : Sometimes two or more crops are grown together in the same field. The crops are chosen in such a way that die products and waste materials from one crop help in the growth of the other. Cotton and groundnut crops are often grown together for this reason.
However, these natural methods alone are not sufficient to maintain the fertility of the soil, and farmers have to add manures arid fertilizers from time to time.
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