1. Water has been applied at the rate of 17 to 25 inches per growing season, the rate varying as the rainfall varies.
2. The total amount of water contained in our planet is constant and invariable.
3. The hydrological cycle comprises a gigantic system operating in and on the land and oceans of the earth and in the atmosphere surrounding it.
4. The sun heating the surface of the ocean, the water vapor rises into the air.
IV
, .
1. If the young researchers applied the new progressive methods of work they would obtain better results.
2. Provided we used machines, equipment, labour and natural resources better, we should achieve greater production volume
3. Were this article on drainage we should read it without dictionary.
V "Land Reclamation and Improvement". :
1. What lands need reclamation and improvement?
2. What can the purpose of drainage be achieved by?
Land Reclamation
There are many lands that are unfit for cultivation because they are too wet or dry. These lands need reclamation and improvement. There are different ways of reclaiming and improving such lands. Drainage and irrigation are the most common practices. The purpose of drainage is to increase the productiveness of agricultural soils.
This purpose can be achieved by removing the free water which excludes air and inhibits the growth and activity of plant roots. Drained soils are more easily and sooner worked. Drainage insures a longer growing season and earlier ripening. The useful action of microorganisms is stimulated, and there is a more rapid liberation of plant food. Irrigation is an important practice in arid regions where the annual rainfall is very low.
All crops need water very much. Some crops are more drought-resistant, others are less drought-resistant. Plants with a long growing season - sugar-beet, potatoes and especially grasses - require more water than cereals. Irrigation is especially useful for orchards.
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I , , , , .
1. The length of growing season and distribution of rainfall during the growing season are of practical importance in determining the amount of water needed to grow sugar beet.
2. Diverting water from flowing rivers and streams is the oldest known practice of obtaining water for irrigating cultivated crops.
3. To control the rivers and to regularize their regimes by storing water in the dry seasons, dams and reservoirs are constructed.
4. Complex systems of pumping stations and canals may be necessary to lift and move the water from the reservoir to the fields.
5. In order to form one kilogram of dry matter wheat draws out of the soil 300-400 litres of water, maize 200-300 litres and cotton 500-600 litres.
6. Water is delivered from open ditches to the areas to be irrigated by means of check structures.
II , . , , , .
1. This soil is found to have much moisture.
2. Drainage is often thought to be needed only in too wet soils.
3. This farm is known to produce high yields of corn, wheat, barley, oats.
4. Everybody knows cultivation of plants to be closely connected with man's progress.
5. The agronomist wants this crop to be watered twice a week.
6. The professor seemed to invite the students to join him in his research of soil fertility.
