NCERT 8th Class (CBSE) Science: Crop Production

Question: What is nitrogen assimilation?

Answer: Nitrogen assimilation is the process by which inorganic nitrogen compounds are converted into organic compounds such as proteins that become a part of living beings.

Question: What enables leguminous plants to fix nitrogen?

Answer: The nitrogen fixing bacterium Rhizobium live in the root nodules of leguminous plants like peas and beans. These bacteria can fix atmospheric nitrogen into nitrates. Thus, enables them to fix nitrogen.

Question:  What is animal husbandry?

Answer: The breeding, feeding and caring of domestic animals for food and other purposes is called animal husbandry.

Question: Distinguish between kharif and rabi crops, giving two examples of each.

Answer: The difference is as follows:

Question: List the steps involved in crop production, in sequential order.

Answer: The steps involved in crop production are as follows:

1. Preparation of soil – Selection of seed and sowing
2. Manuring – Irrigation – weeding
3. Protection from pests and diseases
4. Harvesting, threshing and winnowing
5. Storage

Question: Why is it important to plant seeds at the correct distances from each other?

Answer: Seeds should be planted at a proper distance from each other so that they cannot compete for water, nutrients and sunlight. If they are too far apart, there is wastage of field space.

Question: Why do farmers normally use a mixture of manures and fertilizers in their fields?

Answer: Farmers normally use a mixture of manure and fertilizers in their fields to increase the yield and production of crops. Manure is good for plants as it provides them with organic nutrients but it lacks some important nutrients like nitrogen, phosphorous and potassium. So, along with manure, farmers also use fertilizers such as NPK fertilizers that provide nitrogen, phosphorous and potassium.