No. 7. DEPARTMENT OF AGRICULTURE. 379 



the Polenziusz i)rocess requiring only that the carbide be heated in 

 nitrogen gas to a temperature between 700 and 800 degrees C. The 

 Polenziusz process diliers from the former also in that instead of 

 using lime, calcium chlorid is employed. The former material is 

 now manufactured chielly in Northern Italy where numerous water- 

 falls afford cheap electric power. A lease has been taken for opera- 

 tion in the United States under the Frank «& Caro patent and the 

 estimates of the industrial engineer for (he lessees require an ex- 

 penditure of not more than 10 cents for each pouud of nitrogen con- 

 tained in the manufactured product. His estimates do not include 

 selling costs, but xf they are correctly founded in fact, it would ap- 

 pear that lime nitrogen may very shortly become an article of prime 

 importance in the fertilizer trade. 



The commercial article holds most of its nitrogen in a water-sol- 

 uble form. When applied to plants, it exhibits fertilizing proper- 

 ties. It is not, however, established that plants can take up the lime 

 nitrogen directly, but the experiments of Loehuis and Ashby show 

 that some, possibly many, soil bacteria possess the power of convert- 

 ing the calc'um cyanamid into an ammonium compound, so that lim( 

 nitrogen ailords a source of ammonia that is accompanied not by 

 acids undesirable in excess, but by lime, the substance especially 

 needed in acid soils. 



Within the past four years, hundreds of experiments have been 

 made in Europe to ascertain the fertilizer value of lime nitrogen 

 and of the similar '^nitrogen-lime" (the name '^ StickdofkaW has 

 been adopted for the product from the Polenziusz process). The re- 

 sults of these trials may be briefly summarized as follows: Direct 

 contact of lime nitrogen with germinating seeds was usually very 

 injurious, so much so that replanting was in some cases required. 

 Such injurious effect rarely occured, however, when the lime nitro- 

 gen had been thoroughly incorporated with the soil ten days or two 

 weeks prior to the seeding. It is not thoroughly established to 

 which or how many of the constituents of lime nitrogen this injury 

 may be attributed. In somj cases, where parallel tn-atments with 

 quantities of caustic lime equal to the amount of free lime nitrogen 

 were used, the injury to germinating plants was the same with the 

 lime treatment as with the lime nitrogen treatment, but in other 

 cases, this equality of effect did not appear. Several months have 

 been proposed for such modification of the lime nitrogen as will in- 

 sure the absence of sulfides, phosphides and carbides. For the pre- 

 sent, it is sufficient to know that by early enough application of the 

 material to the land, its injurious effects upon germinating seeds 

 can be avoided. 



Practically all experiments in which it was used as a top dressing, 

 in comparison with nitrate of soda and sulfate of ammonia, show a 

 great inferiority of the lime nitrogen to the other material in the 

 resulting gains of plant ])roduction. There is strong evidence that, 

 when applied as a top dressing, the lime nitrogen loses nitrogen, 

 probably in the form of ammonia. Furthermore, when so applied 

 in considerable quantities, it has been found in some instances to 

 seriously injure the crop. For this reason, it offers no present pro- 

 mise as a substitute for the nitrate of soda and the sulfate of am 

 monia now so widely employed for top dressing purposes. 



