374 ANNUAL, REPORT OF THE Off. Doc. 



affecting the amount or quality of the product. But the variation 

 cannot go beyond certain limits -without in some way affecting the 

 product. AA'liile in feeding plants the lines are not so definitely 

 marked, yet certain it is that for best results some attention must 

 be paid to the supply and availability of the soil derived elements 

 likely to be deficient in the available form, viz: Nitrogen, phosphoric 

 acid and potash. 



As in feeding animals the proteids or nitrogen bearing constitu- 

 ents are the expensive parts of the ration, so in feeding plants, the 

 nitrogen is the expensive element if it must be purchased in the 

 market. 



While we cannot say that any one of several necessary elements 

 is more important than the others, yet in securing a balanced ration 

 for plants the nitrogen usually demands the most attention. It is 

 this element which is most easily lost from the soil. A superabund- 

 ance of it in the soil may over-stimulate the vegetative system and 

 produce a large growth of plant and foliage, but at the expense of 

 fruit and grain. Too much nitrogen may also cause a growth which 

 is lacking in hardiness and the plant is likely to become the victim 

 of blight and disease. A deficiency of nitrogen, on the other hand, 

 means the slow growth, lack of woody tissue and foliage, and lack of 

 fruit and grain, because the factory or plant is deficient in capa- 

 city. 



Nitrification or the changing of compounds containing nitrogen 

 into the form of the nitrates, a form available for plants, takes 

 place most rapidly when the soil temperature is from 90 to 100 de- 

 grees Fahrenheit. It will thus be seen that in the early spring when 

 the soil is cold that plants may suffer from lack of nitrogen, when 

 later in the season there ma}' be an abundance of nitrogen made 

 available through the process of nitrification. If it is desired to 

 stimulate the growth of plants in the early spring, some quick acting 

 form of nitrogen should be used, as the nitrate of soda. This is found 

 to prove especially valuable when wheat or grass in meadow or 

 pasture are slow in beginning growth in the spring. It would be 

 folly in such cases to apply slow acting nitrogen because it could not 

 be made use of before the temperature and soil conditions were 

 favorable for nitrification and then no commercial nitrogen would 

 be needed. 



Where it is known that a certain soil is deficient in nitrogen and 

 that plant growth is likely to be slow even during the periods when 

 nitrification is most rapid, commercial nitrogen should be applied, 

 a part of which is in the quick acting form, as nitrate of soda, and 

 a part should be in slower acting foims, as dried blood, tankage, 

 cottonseed meal, or other organic forms of nitrogen, all of which are 

 gomewhat slower in their action than is nitrate of soda. The h^\- 



