Agricultural practices — Class 8 CBSE Science MCQs with Solutions

Solution: A crop is plants of the same kind grown together at one place on a large scale.

Solution: Paddy is sown in the rainy season (June-September), making it a kharif crop; wheat, gram and mustard are rabi crops.

Solution: Wheat is grown in the winter season (October-March), making it a rabi crop; maize, soyabean and cotton are kharif crops.

Solution: Manure is organic, formed by the decomposition of plant and animal waste by microorganisms.

Solution: Rearing animals on a large scale with proper food, shelter and care is known as animal husbandry.

Solution: NPK stands for Nitrogen, Phosphorus and Potassium.

Solution: The correct order is preparation of soil, then sowing, then adding manure and fertilisers, irrigation, protecting from weeds, harvesting and storage.

Solution: Manure adds humus to the soil, whereas chemical fertilisers such as urea, ammonium sulphate and NPK provide no humus.

Solution: Growing leguminous crops in rotation replenishes the nitrogen content of the soil.

Solution: Weeds compete with the crop for water, nutrients, space and light.

Solution: 2,4-D is a weedicide, a chemical sprayed to kill weeds without damaging the crop.

Solution: A khurpi is used to remove weeds manually by uprooting them; a sickle is for harvesting, a seed drill for sowing and a leveller for levelling soil.

Solution: A fertiliser is a chemical made in factories that is rich in a particular nutrient, unlike organic manure, which is prepared in fields and adds humus.

Solution: A seed drill sows seeds uniformly at equal distance and depth, covers them with soil, protects them from birds and saves time and labour; it does not test seeds, add nutrients or remove weeds.

Solution: Rhizobium lives in the root nodules of leguminous plants and fixes atmospheric nitrogen.

Solution: Paddy requires a large amount of water, which the rainy kharif season provides, so it is not grown in the dry winter.

Solution: Manure improves soil texture and increases its water-holding capacity, which chemical fertilisers such as urea, superphosphate and potash cannot do.

Solution: Drip irrigation lets water fall drop by drop directly near the roots so almost no water is wasted, and it is the best method for fruit plants and trees where water is scarce. A sprinkler sprays over the whole field (better for uneven land and lawns), while moat and flooding waste much more water.

Solution: Overusing chemical fertilisers reduces soil fertility and pollutes water bodies; unlike manure, fertilisers add no humus.

Solution: Spraying before flowering and seed formation kills weeds while they are young and stops them from producing seeds and spreading.