V. Define the Gerund in sentences, determine its function. Translate the sentences.

1. Experiments have shown that increasing the concentration o an ion the soil solution up to a certain point will increase the intake of that ion.

2. Early chemists studied the causes, methods of determining and procedure for changing soil reaction.

3. By growing plants in nutrient solutions o varying PH values it was determined that roots are definitely damaged at PH of 3.

4. The presence of a growing crop is one of the best methods of decreasing leaching losses.

5. In discussing the average calcium content of plants- it should be borne in mind that the percentage of calcium in different specimens of a given plant species is by no means uniform.

6. Liming the soil usually involves the application of considerable quantities of magnesium.

7. The purpose of soil testing is determining the available supply of the major plant nutrients in soil.

8. Al types of farming have a part in the formation and destruction of organic matter.

9. Chemical soil tests for determining fertilizer needs are widely used.

10. Adding fertilizer to the soil aids in reducing erosion losses because it produces more plant covers.

11. If a lot of residues is present on the surface at seeding time, some difficulty may be experienced in doing a satisfactory job of drilling.

12. Stubble mulch helps to control wind erosion by reducing surface wind velocity.

13. Surface inlets are suitable for carrying surface water into the tile drains.

14. Soil tests afford an excellent control for determining erosion losses during hard rains.

15. To prevent leaching we must grow deep-rooted crops or rapid-growing crops.

16. In developing from the bare rocks not one soil but many soils were formed.

17. Splashing occurs when a raindrop falls on protected soil.

18. Trees and grasses are the best crops for controlling surface runoff.

VI. Find the Infinitive in sentences, define its function. Translate the sentences

1. Bones were the first materials high in phosphorus content to be used as fertilizers.

2. It is well known that certain plants have capacity to absorb and store large quantities of potassium.

3. The tendency of phosphorus to hasten maturity of plants is modified by ample supplies of potassium.

4. Calcium salts are applied primarily to change conditions in the soil.

5. Magnesium is applied primarily to correct a deficiency of the element as a plant nutrient.

6. A third system of using green crops is to seed them with the major crop and permit them to grow after the crop is harvested.

7. In clean- cultivated orchards plants as green manure are often seeded in the late summer in order to utilize excess nitrates.

8. Clays have the capacity to hold plant nutrients in available form on their surfaces.

9. The removal of excess water from soils is desirable in order to improve aeration.

10. For crops to be grown the most important factors are: climate and soil fertility.

11. Boron enables plants to absorb or utilize calcium.

12. Organic matter helps to keep phosphates available in soils.

13. The demand for fertilizers to be used on crops is great.

14. It is difficult to overestimate the importance of ion fixation to soil productivity.

15. To understand the sediment problem, it is necessary to understand its relation to erosion.

16. The ability of wind to transport soil is enormous.

17. A dust storm on March 25, 1895, was estimated to have loaded the atmosphere with 1,600 ton of dust per cubic mile of air at Rock Island Illinois.

18. In order to have stable granulation there must be a cementation of the flocculated.

19. The major role of plant cover is to protect the soil from the force of falling raindrops.

20. Siphon tubes made of metal, plywood or plastic are widely used in irrigated areas to transfer water from the field ditch to the land to be irrigated.

21. Where the quantity of surface water to be removed is small and amount of sediment is too great to permit surface inlets to be installed, blind inlets may improve drainage.

22. Relief wells to prevent blowouts of a title system are generally recommended.

23. Crops are rotated in order to maintain the productivity of soil.

24. The purpose of drainage is to remove excess water from the root zone as quickly as possible.

25. Windbreaks can be used to control wind erosion where the rainfall is enough to support trees.