NITROGEN GATHERING 173 



will not produce a large crop of any legumkious 

 plant unless well supplied wdtli phosphoric acid 

 and potash. Therefore, in attempts to increase the 

 protein supply of the farm by means of leguminous 

 plants, it is quite as necessary to fertilize with the 

 minerals as it would be to grow any other crop. 

 This is entirely reasonable, as the mineral constit- 

 uents cannot be secured from any other source 

 than the soil and these are quite as essential to 

 leguminous crops as to any others, or as the nitro- 

 gen itself. 



Kinds of leguminous crops 



The family Leguminosae, or pulse family, is 

 very large and it is represented in the flora of all 

 parts of the globe. Some of the legumes are trees, 

 as locusts, red-bud, yellow-wood; others are 

 bushes, as furze, broom, lead -plant; some are 

 tall woody climbers, as wistaria; others are agri- 

 cultural herbs, some of which are grown for for- 

 age, as alfalfa, clovers, cowpea, soybean, velvet- 

 bean, vetches, pea, and these are to be considered 

 further in the three chapters that follow. 



