118 WHEAT 



time. Certain crops adapted to the west are being 

 tested for this purpose; the most promising are 

 sand vetch and sweet clover for fall seeding and 

 field peas for spring seeding. These crops are 

 hardy rapid, growers and somewhat drouth re- 

 sistent and may be used in part for pasture, thus 

 giving some return other than their fertilizing 

 value. . 



VARIOUS EXPERIMENTS 



Wheat sown directly after green manuring 

 with field peas, has not given as high yields as 

 when sown after a bare fallow. Sand vetch is 

 safer to use because it may be seeded in the fall 

 and is ready to plow down early in the spring. 



An experiment in green manuring in wheat 

 rotations at the North Dakota experiment station 

 indicates, that as the supply of organic matter 

 decreases, the benefit from green manuring in- 

 creases. This experiment has been carried on for 

 twenty years, a crop of field peas or millet being 

 plowed down every fourth year. The results of 

 green manuring on the succeeding yields of wheat 

 compared with the same rotation in which the 

 peas and millet crops were harvested is given in 

 Table IX. 



TABLE IX 



Showing the influence of green manuring upon 

 wheat yields by periods of five years (1892-1906), 

 Bui. No. 100 North Dakota experiment station: 



