684 IOWA DEPARTMENT OF AGRICULTURE 



of these is "Parmogerin" manufactured by Earp Thomas Farmogerm 

 Company, Bloomfield, New Jersey; and the other "Nitragin" manufac- 

 tured by the German-American Nitfagin Co., Milwaukee, Wisconsin. Both 

 of these pure cultures have been used on the Iowa Agricultural experi- 

 ment station plots, though the tests have not been thorough enough as 

 yet to permit unreserved recommendation. While the effect of the in- 

 oculation was very apparent, it is possible that just as great a benefit 

 might have resulted from the use of inoculated soil. The claim is made 

 among bacteriologists, however, that the pure cultures may add to the 

 soil not only a great number of bacteria, but also bacteria which are 

 more virulent and vigorous than those already found there. However, 

 until more tests have been made, we believe that the soil inoculation 

 must be recommended. 



THE USE OF LIME 



The co-operative alfalfa tests indicate that at least on many Iowa 

 soils the use of lime is to be recommended. Its application has in many 

 cases been very beneficial. No harm can come from an application of 

 2,000 or more pounds per acre especially if this be in the form of lime- 

 stone screenings or finely ground limestone, which are the best forms 

 to use. One thousand to 3,000 pounds will no doubt be sufficient on most 

 Iowa soils though on similar soils in adjoining states experiments have 

 shown that in some cases as much as 6,000 pounds are necessary. 



In a number of instances in this state application of lime was shown 

 to be absolutely essential before alfalfa could be grown successfully, in- 

 dicating that the soil was strongly acid. In other cases while a satis- 

 factory growth was secured without the use of lime, yet when it was used 

 the growth was more vigorous and of better color. 



Alfalfa requires for its best growth a large amount of calcium, which 

 is the active principle of lime. Also alfalfa cannot grow and thrive in 

 soils which are at all acid. The nitrogen-gathering bacteria, which live 

 upon the alfalfa roots, and which in turn provide the alfalfa plant with 

 most of its supply of nitrogen, cannot live, thrive and multiply in an 

 acid soil. 



Soils may be tested for acidity easily by the use of litmus paper. 

 Take soil from a few inches below the surface of the ground and after 

 thoroughly wetting it, press it into a ball. Halve it with a knife and 

 after placing a piece of blue litmus paper between the two cut sur- 

 faces, again press parts into a ball. At the end of ten or fifteen minutes 

 remove the litmus paper and examine. If it has changed from blue to 

 a distinctive red color, one may be reasonably sure that the soil is acid 

 and is in need of lime. 



Litmus paper can be secured at any good drug store. 



Lime should be applied after plowing and thoroughly disked in, pref- 

 erably some weeks in advance of seeding. It may be spread from a 

 wagon with a shovel or a manure spreader may be used. An old broad- 

 cast grain seeder may also be used. 



Those who contemplate seeding alfalfa should send for Circular No. 2 

 of the Iowa Experiment Station, "Liming Iowa Soils." 



