164 CHOP GROWING AND CHOP FEEDING 



made to yield up its nitrogen to our crops. This process, by which organic 

 matter has been so acted upon as to contribute to the growth of crops, has 

 for many years been a subject that has engaged the attention and occupied 

 the time of the scientific investigators all over the world. The conditions 

 necessary to nitrification, or the formation of nitrates for the use of green 

 plants, have been carefully investigated. The result of these investigations 

 shows beyond doubt that nitrification in the soil is the work of a living 

 organism, and of more than one kind of organism. 



These organisms belong to that low order of vegetation just barely 

 within the reach of the power of the modern microscope, and known by the 

 general name of bacteria. Plants which have green matter in their tissues 

 we have shown to have the power of getting carbon, which is essential to their 

 structure, through the power their green matter has of decomposing the car- 

 bonic acid of the air and taking therefrom the carbon they need, while at the 

 same time restoring oxygen to the air; and it has generally been assumed 

 that the low orders of a fungoid character, having no green matter, were 

 compelled to get the carbon to form their tissues from the organic matter of 

 living or dead green plants. But one of the greatest discoveries in connec- 

 tion with the nitrifying organisms is the fact they are not dependent on 

 organic mater for their carbon, but can get it from such mineral combinations 

 as carbonate of lime ; and this is one of the reasons for the importance of lime 

 in promoting nitrification in a clay soil containing organic matter. The nitri- 

 fying organism can use organic carbon, but can also use the inorganic com- 

 pounds containing carbon for its growth. 



CONDITIONS ESSENTIAL TO THE FORMATION OF NITRATES IN THE SOIL. 



While it is possible for the nitrifying organisms to get carbon from in- 

 organic compounds, all investigations have shown that organic food is essen- 

 tial to their activity, and the work they are to do. They must also have a 

 supply of oxygen. Nitrification will not take place in a soil saturated with 

 water, excluding the oxygen of the air; hence the importance of drainage 

 in a soil abounding in nitrifiable organic matter. Muck in the swamp does 

 not nitrify, though almost entirely composed of organic matter; hence, too, 

 the importance of tillage in promoting the aeration of a heavy, clay soil. 

 Neither can nitrification, or the formation of nitrates in the soil, take place 

 unless there is some base in the soil for the nitric acid to unite with. These 

 bases are alkaline in their nature, and the process of nitrification requires a 

 feebly alkaline condition in the soil. Not only is nitrification in muck pre- 

 vented by the presence of water shutting out the oxygen of the air, but also 



