Aug. 13, I9I7 Effect of Paraffin on Ammonia and Nitrates in Soil 361 



When ammonium sulphate was added to the soil either with or without 

 calcium carbonate, all three forms of paraffin exerted a very marked effect 

 upon the accumulation of nitrate nitrogen. The decreased accumulation 

 of nitrate nitrogen was not so evident during the early stages of incu- 

 bation except with paraffin oil. With the oil the effect again seems to 

 be to retard nitrification, the quantity of active nitrogen approaching 

 very closely that in the controls. Parowax and paraffin, however, not 

 only decrease the accumulation of nitrate nitrogen but also bring about 

 a large reduction in the quantity of active nitrogen. The reduction in 

 active nitrogen occasioned by the various forms of paraffin is not nearly 

 so rapid where ammonium sulphate was added as where nitrogen in the 

 form of cottonseed meal was added. This is probably due to the food 

 elements other than nitrogen contained in the cottonseed meal. 



In the experiments thus far given the mass of soil used was only 100 

 gm. In order to ascertain whether coating the containing vessel with 

 paraffin would exercise an appreciable effect upon NO3 accumulation if 

 the volume of soil were larger, the following experiments were carried 

 out. The inside of a glass jar 5 inches in diameter was coated with 

 paraffin, another was coated with Parowax, and a third was left un- 

 treated. The jars were all filled with loose soil containing optimum moist- 

 ure and calcium carbonate. After seven weeks of incubation the soil of 

 each jar was mixed and analyzed for NO3. The following quantities, 

 expressed as milligrams of NO3 per 100 gm. of soil, were found to be 

 present: Untreated jar, 7.1 mgm.; paraffined jar, trace; Parowaxed jar, 

 trace. 



At the same time a 2-gallon earthenware jar 8X inches in diameter 

 coated on the inside with paraffin and another untreated were filled with 

 the same soil and incubated the same length of time. Upon analysis a 

 central column of soil 2X inches in diameter was removed from each jar 

 and analyzed separately. The milligrams of NO3 per 100 gm. of soil from 

 the central core and from the remaining soil in each jar were as follows: 



Center. Rexaainder. 



Untreated jar 7.6 7. 8 



Paraffined jar 5. 3 1.2 



The closest that the central column came to the surrounding paraffin 

 was 3 inches, yet the paraffin caused a reduction of approximately one- 

 third in the accumulation of nitrate nitrogen. It is evident, there- 

 fore, that the effect of paraffin upon NO3 accumulation can be exerted 

 over an appreciable distance. These experiments show that no ordinary 

 sized container used for cultural purposes can be protected with a coating 

 of paraffin, as in these experiments, without the available nitrogen content 

 throughout the whole mass of soil being affected. 



