REQUIREMENTS FOR PRODUCING PROFITABLE CROPS. 



15 



the growing peas or rye well under, where they will readily decay, 

 after which the soil should be well harrowed immediately. 



Effect of Deep Plowing and Green Manuring. 



The effect of deep plowing and green-manure crops upon the 

 yield of wheat, as determined by observation and actual experiment 

 (see figs. 2, 3, 4, and 5), is shown in Table I, these yields being ob- 

 tained at Modesto, Cal., in 1909. 



INCREASED YIELDS. 



While the results indicated are not entirely conclusive, for the 

 reason that they are not based upon trials extending over a long 



Fig. 4.— Wheat growing on plat on which rye and vetch were grown and plowed under in 1908. (See 



figure 1, E.) 



series of years, they give an idea of what may be accomplished by 

 the deep plowing under of green-manure crops. As indicated, horse 

 beans used as green manure appear to give better results than peas. 

 However, they have a very thick and heavy stalk, and an enormous 

 quantity of seed is required on account of their habit of growing a 

 single stalk from each seed. They are not recommended in the place 

 of peas, which will give better results in combination with rye as a 

 green-manure crop. 



32912— Bui. 178—10 3 



