92 SCHOOL AND HOME GARDENING 



for plant growth, they are soluble in water and are easily 

 washed out by rains. For this reason the application of such 

 fertilizers should be made while the plants are growing, or 

 when the plants are ready to make immediate use of them. 

 Some fertilizers contain the nitrogen in the form of animal 

 and vegetable compounds. Such is the case with fertilizers 

 derived from meat scrap, dried blood, cottonseed meal, tankage 

 and others. In these the nitrogen may not be ready for plants 

 to make immediate use of it. The waste will be less, but 

 the growth will not be so quickly stimulated. If nitrate of 

 soda or sulfate of ammonia be applied, the nitrogen contained 

 in them will be more quickly available for the plants, and the 

 growth will be more rapid from the start. If these latter 

 forms be used before the plants are started, some loss would 

 take place. 



2. Effect of Nitrogen. — In two window boxes or cans containing 

 growing plants, study the value of nitrate fertilizer. Place one tea- 

 spoonful of nitrate of soda in a quart of water. Stir until dissolved. 

 Label bottle and use this to water one box or can of plants, the other 

 being supplied with pure water. After a few weeks of this treatment 

 some diilerence in their growth should be observed. 



Nitrate fertilizer tends to increase leaf growth and retard 

 the formation of blossoms and fruit. In the garden, such 

 plants as lettuce, celery, cabbage and spinach will be greatly 

 aided by the use of nitrate fertilizer, because the stem and 

 leaf growth is desired. Young fruit trees should be fed 

 abundantly with fertilizers rich in nitrogen. 'Wlien they reach 

 bearing age, less nitrate should be used. Then, potash and 

 phosphoric acid should be given in excess. Xitrogen pro- 

 duces dark green leaf growth ; phosphoric acid produces stem 

 and root growth and gives strength to the whole plant ; potash 

 checks leaf growth and causes the early formation of fruit. 



3. How Much Nitrogen to Apply.— Select four cans with per- 

 forated bottoms. Nearly fill thera with samples of garden soil which 

 you wish to test. Have growing in these, corn or any other garden 

 plants you wish to use where the samples were taken. Can No. 1 



