What is mulching? Ans: Soil must be covered with shallow cultivation. The stumps of the plants should not be removed after harvesting. They act as natural mulch and increase the water holding capacity of soil. Straw mulch is also affective in reducing to aporat ion of water.
- What is biodiversity? What are total numbers of species?
Ans: The variety of living organisms in an ecosystem is called biodiversity. The exact number of species in the world is not known. The taxonomists have described about 1.4 million species. But taxonomists estimate that there are 4 to 30 million more species.
- Define conservation.
Ans: The management of the earth resources to restore and maintain balance between human requirement and other species in the world is called conservation.
- Give two methods to conserve energy.
Ans: Develop and use energy efficient machines, engines and manufacturing processes. Reduce wastage by recycling. There should be least use of vehicle. Go by walk or by public transport.
- What is water logging?
Ans: The soil which is saturated with water is called water logged soil and this problem is called water logging.
- Give two effects of water logging.
Ans: Water logging and salinity destroy the soil structure. Different layers of the soil are badly affected. The soil is saturated with water. Therefbre, the oxygen content of the soil is decreased. Thus oxygen is not available to the roots of the plants for respiration. So the plants die.
- What is salinity?
Ans: The soil in which salt crust is left due to evaporation of water is called saline soil and this problem is called salinity.
- What is flushing?
Ans: Saline soil contains chlorides and sulphate of sodium and potassium. These salts are soluble in water. These salts can be leached out with the help of water. This water can be passed into drains. This process is called flushing.
- Name plants used to reclaim saline soil.
Ans: Some grasses like Sporoholus arabieus, Cynodon thetylon, Chloris harhata and herbs like Melilotus &bus, Trifoliunt ft:gentler:tot are grown itt saline soils.
- What is crop rotation?
Ans: The land should not be left naked in any part of the year. It should always be remained covered with crops. Leguminous plants should be grown after cotton. Some grasses are used as fodder. They can be grown as soil cover.
- What are watershed and watershed management?
Ans: An area from which water fall in the form of rain or snow collects into a stream and river is called watershed. The storage of water for irrigation and for producing electricity by constructing dams and barrages is called water shed management.