Geography (Part-3) Increasing Arable Land & Land for Use

Описание: #geography #arable #irrigation #terracegardening
Unit 3:
3. Increasing Arable Land:
Only about 30% of the Earth’s surface is covered by land. Of this total land surface, only about 11% is presently used for crop cultivation. The land on which crops are grown is called arable land. The remaining 89% of the Earth’s land surface is non-arable. This includes areas where the physical conditions are unsuitable and areas which are used for other purposes such as housing & industries.
However, most of the arable land has physical conditions that are favorable for crop cultivation. These physical conditions are:
Suitable temperatures
Adequate rainfall
Generally flat land
Fertile soil

Plants require suitable temperatures to germinate & grow. For example, rice needs a temperature of at least 21oC to grow while wheat needs a temperature of between 15oC & 21oC. In general, the minimum temperature for plant growth is 6oC.
Besides suitable temperatures, plants also need an adequate supply of water. The water requirement varies from crop to crop. For example, an annual rainfall of 2000 mm is ideal for rice but millet needs less than 1000 mm per year.
Another physical condition that favors cultivation is flat land. It is easier to use machines and to retain water for cultivation when the ground is level.
Fertile soil is also essential as it provides plants with the nutrients they need. For instance, wet rice grows best in areas with fertile alluvium.

A. Why Increase Arable Land?
Increasing Population:
A.D Population in Billions
2000 6
1950 2.4
1900 1.8
1850 1.3
1700 0.5

In Niger & Nigeria, population growth is very rapid. In fact, almost 75% of the world’s population is found in developing countries but they have only about 55% of the world’s arable land.

B. Loss of Existing Arable Land:
The U.N estimates that by the year 2000, the world will lose farming land at the rate of 300,000 hectares (ha) (100 hectares = 1 square km) a year.
Existing arable land is lost partly because of changes in land use. For instance, when towns & cities expand, land is required for housing, factories & roads. As a result, some of the arable land near these towns and cities is converted to other uses. In California, USA, as the cities & industries expand, arable land is being lost at a rate of between 24000 & 30000 hectares each year.
Land is also lost as a result of poor farming practices. For example, in some areas, farmers plant one crop after another without letting the soil rest. With time, the nutrients in the soil are being used up and the soil becomes infertile. The damaged land becomes useless and no crop can grow on it.

C. More Arable Land:
Forests can be cleared and swamps can be drained to make them suitable for growing crops. Cultivation can also take place in dry areas by irrigation, on steep slopes by terracing and in infertile areas by adding fertilizers to the soil. With the help of technology, farmers can reap more crops from each harvest or have more than one harvest a year.

D. How to Increase Arable Land?
Irrigation:
Irrigation is the practice of supplying water to the land by artificial means. For example, much of Pakistan annual rainfall below 375 mm. As a result, much of Pakistan cannot be cultivated. With the help of irrigation water has been brought to the dry areas in Pakistan and has created millions of hectares of arable land.
Irrigation enables rain water to be collected and stored in the wet season for use during the dry season. Cultivation is only possible during the wet season.
Around 6000 BC, farmers were already practicing irrigation along the Nile River. To ensure a regular supply of water for irrigation throughout the year, people build dams. Dams are walls built across rivers to hold back water. To distribute water, canals can be constructed.
Terracing:
Another method of increasing arable land is to make steep slopes more suitable for crop cultivation by terracing. Terracing is the method of creating flat strips of land by cutting steps on a slope. These flat strips of land are called terraces. Terraces is used mostly in Philippines and Indonesia.
Using Fertilizers:
Fertilizers are substances containing minerals which are necessary for plant growth. There are generally two types of fertilizers; Natural & Chemical fertilizers.
Natural fertilizers are animal waste and crop waste. In parts of China and South Korea, human waste is also used to fertilize crops.
Chemical fertilizers are produced in factories. Fertilizers containing different minerals such as nitrates, phosphates or potash can be packaged separately.


Previous videos on Geography
Part-2 Making Movement Easier    • Geography (Part-2) Making Movement Easier  
Part-1 Natural Resources    • Geography (Part-1) Natural Resources