332 FIELD CROPS 



present on the seed, complete inoculation is often obtained 

 by gradually increasing their number. This is best done 

 by mixing a small quantity of the seed of the legume desired 

 along with the grass seed. In a few years the bacteria will 

 have increased sufficiently to insure the success of a straight 

 legume seeding. Special inoculation is not often necessary 

 except for alfalfa, and is not always essential for the success 

 of that crop. A liberal application of barnyard manure, 

 particularly that from stock fed alfalfa hay, is very helpful 

 and often meets all requirements. 



LABORATORY AND FIELD EXERCISES 



Dig up any of the common legumes carefully when they are grow- 

 ing rapidly during the late spring or early summer, and examine the 

 nodules on their roots. These nodules are of quite different shapes 

 and sizes on different plants. If they can be examined under a high- 

 power microscope, they will prove still more interesting. It may be 

 possible to find fields of alfalfa or some other legume where the nodules 

 are not present and others where they are. Note the difference in 

 growth. The instructor may provide an illustration of this kind by 

 planting seeds of red clover or some other legume common in the 

 neighborhood in ordinary soil in one pot, and seed which has been care- 

 fully washed to free it from nitrifying bacteria in soil that has been 

 baked long enough to sterilize it in another pot. This should be done 

 long enough before this lesson is reached to allow the plants several 

 weeks' growth or, if there is sufficient time between this lesson and the 

 close of the school year for the plants to make the necessary growth, 

 the pupils may do the planting and watch results. 



REFERENCES 



Cyclopedia of American Agriculture, Vol. II, Bailey. 



Agricultural Bacteriology, Conn. 



Feeding of Crops and Stock, Hall. 



Forage and Fiber Crops in America, Hunt. 



Field Crop Production, Livingston. 



Productive Farm Crops, Montgomery. 



Clovers and How to Grow Them, Shaw. 



First Principles of Soil Fertility, Vivian. 



Meadows and Pastures, Wing. 



