200 



LEGUME INOCULATIOX. 



IMartin J. Prucha. 



(Circular No. 15, Department of Plant Physiology, Cornell I'niversity 

 Agricultural Experiment Station.) 



During the past ten years much interest has been created in the 

 use of atmospheric nitrogen by bacteria associated with the 

 legume crops. The Depart- 

 ment of Plant Physiology at 

 Cornell University has re- 

 ceived, within recent years, 

 a considerable number of in- 

 quiries with respect to the 

 subject. These inquiries have 

 been particularly concerned 

 with the introduction of the 

 root-nodule-forming bacteria 

 into fields. Questions re- 

 specting the "how" and the 

 "when" to inoculate have 

 been numerous. Many of 

 the letters reveal the fact 

 that the writers possess 

 vague or erroneous ideas 

 concerning inoculation. Dur- 

 ing the past few years the 

 department has been investi- 

 gating the subject. In order 

 to set forth briefly and sim- 

 ply the essential facts, as 

 well as to call attention to 

 the pure cultures that the 

 department is now distrib- 

 uting, this circular is pre- 

 sented to the public. 



Vu: 



;{i). — Jloot of s(>i/ Ixtin, showing 

 nodules. Ncitural si:c. 



diffi-:ri-:nci-:.s nirrwi-iEN legumils .\x\i) oiiii-.k tlanis. 



Leguminous crops are very rich in i)rotcin. .Mfalfa hay, for 

 cxam])le, is almost as rich in nitrogen as is wheat bran. In fact, 

 all the leguminous crops, whether in the form of hay or of seed, 

 dififer from other cro])s in that they are richer in nitrogen con- 

 tent. They are, therefore, very valuable crops. 



There is another point of difference between legumes and <~>tlier 

 ])lants. If a leguminous plant is carefully dug u]) and the roots 

 are washed, a number of wart-like swellings may be seen on the 

 roots. Tlicse swellings arc commonly called nodides. Photo- 



