Oral work :
Name the leguminous crops cultivated to restore the fertility of soil .

Name the following: GM crops.

Give reasons: Denitrification reduces the fertility of the soil.

Oral work : What causes a tsunami?

Why do farmers use leguminous crops to provide nitrogen to the soil? Explain.

Name the triploid nutritive tissue formed after fertilization.

Select the appropriate options and complete the following paragraph. ( organic farming, humus, oxidation, increase, pesticides, fertilizers, nitrogen, biomagnification, decrease) The uppermost layer of soil is made up of ---that is essential in agriculture. Essential elements like ___ , phosphorous and potassium need to be made.available to the crop plants. Chemicals used in agriculture, __ _ the fertility of soil. Use of ___ like DDT 1iave also. proved to be dangerous, since the poison enters the food-web and causes problems due to -,-----of the compound. To overcome these problems, farmers are opting for the practice of ___ .

Oral work : Name some natural phenomena.

Oral work : Name the device installed on the top of the buildings to pretect it from a lightning strike.

State whether the statement is true or false. Correct the false statement : Chemical fertilizers increase the fertility of soil.

Why do farmers grow leguminous crops after harversting cereal crops?