SURROUNDINGS OF THE HOME 251 



plant growth. The need of a dust mulch during the hot dry 

 weather of summer is especially true with gardens where the 

 soil is likely to be heavy and compact, and in semi-arid 

 regions where the rainfall is normally deficient. 



Enough air must be present in the soil to favor the activity 

 of the bacteria concerned in decay of organic matter as 

 humus, and to furnish nitrogen to the bacteria that thrive 

 upon the roots of peas, beans, clover, alfalfa and other leg- 

 umes. Although nitrogen as a chemical element is essential 

 to plant growth, plants cannot appropriate it as an element 

 directly from the air. It must be in the form of nitrates or 

 other nitrogen compounds, and these must be dissolved in the 

 soil water. The " nitrogen-fixing " bacteria as a lower form 

 of plant life are active agents in maintaining the. fertility of 

 soils. They are an agency in the preparation of food material 

 for the more highly developed forms of plants, even as these 

 higher plants in their turn prepare food for animals. The 

 soil, then, is not to be looked upon as dead lifeless material, 

 but as filled with life and activity. Nitrogen compounds 

 suitable for fertilizing soils are now prepared in several of 

 the countries of Europe direct from the atmosphere by means 

 of electrical discharges in a series of chambers through which 

 an air current is kept moving. Congress has authorized 

 (1916) the establishment of a great electrical plant in the 

 United States for the production of nitrogen compounds from 

 atmospheric nitrogen for use in explosives and for agricultural 

 needs. 



So important is a proper preparation of the soil before 

 seeding or planting that any amount of later cultivation 

 during the season cannot make good an early neglect.. What 

 the particular preparation shall be for any piece of ground 

 will, of course, depend much upon the soil. College courses 

 in soils and in cereal crops will fail to bring success to any 

 farmer who does not exercise the best of judgment in fitting 



