Grade-8 Podar International School,Gandhinagar

Q:   Describe the importance of weedicides, manures and fertilisers in good agricultural practice. Ans: Weeds: weeds are unwanted plants that grow along with crop plants and compete with them for water, nutrients, space and light, thus they effect growth of crop plants. Some of the weeds are poisonous for animals and human beings and they interfere even in harvesting of crop plants. Weedicides are chemical that are sprayed in the fields to kill the weeds, they do not damage the crops. Weedicides are diluted with water and are sprayed in the field by sprayer to kill the weeds. Q.what is n itrogen cycle? Write down its steps Air contains about 78% nitrogen. Nitrogen is used by life forms for the formation of protein, amino acids and nucleic acids. The cyclic process of nitrogen being fixed, used by plants and animals and later returned to the atmosphere is referred to as the nitrogen cycle. Nitrogen cycle involves the following steps: Nitrogen fixation:  fixing free

Food sources and use  Question 1 Write a note in your own words on each of the following. (a) Preparation of soil (b) Sowing (c) Weeding (d) Threshing Answer: A.Preparation of soil: 1This method is usually employed for loosening called tilling or ploughing the soil.the soil to allow the root to penetrate deep into it. 2.Plants require nutrients for their proper growth and functioning. Tilling of soil brings the nutrient-rich soil to the top. This helps the plants to utilize the nutrients for their growth. 3. The loosening of the soil helps in the growth of several soil microbes, earthworms etc., which enrich the soil with humus and other essential nutrients. (b)Sowing: It is the process of placing the seed in or on the soil for future growth. a. The seeds that are selected for growing should be of good quality. This will improve the net yield of the crop. b. Sowing is usually done with the help of either a traditional tool or a seed drill. The traditional t