638 EXPERIMENT STATION EECOED. 



Effect of deep plowing and green-manure crops on wheat yield. 



Preceding treatment or crop. 



Yield at 

 Davis, 

 1907-10. 



Bare fallow 



Horsebeans (turned under) 



Canadian field peas (turned under) . 



Wheat after wheat 



Rye and vetch (turned under) 



Rye (turned under) 



Bur clover (turned under) 



41.6 

 42.7 

 43.3 

 35.6 

 44.4 



48.2 



" One year only. 



The Ceres soil is sandy, tliat at Davis is heavy, normally richer in humus, 

 and more retentive of moisture. The fourth plat at the Ceres station was 

 summer fallowed in 1906 and produced yields of 41 and 26 bu., respectively, 

 in 1907 and 190S. 



Among crops to be used for green manuring the author believes that the 

 most favorable immediate results can probably be secured by the use of rye 

 and that the experiments indicate the determining factor to be the " mass 

 of green stuff that can be introduced into the soil rather than the character 

 of the material." In the Sacramento Valley peas seeded at the rate of about 

 100 lbs. per acre have given good results but on the lighter soil of the San 

 Joaquin Valley they do not make so rank a growth. 



In a fertilizer test at Davis the highest wheat yields, 44.7 and 42.6 bu. per 

 acre respectively, followed applications of (1) 100 lbs. of nitrate of soda, and 

 (2) 100 lbs. of nitrate of soda and 240 lbs. sulphate of potash per acre. The 

 highest barley yield, 22.1 bu. per acre, followed an application of 100 lbs. of 

 nitrate of soda and 2,650 lbs. hydra ted lime per acre, while applications of (1) 

 200 lbs. of nitrate of soda and 400 lbs. superphosphate and (2) 100 lbs. nitrate 

 of soda, 1,000 lbs. superphosphate, and 120 lbs. sulphate of potash per acre 

 were followed by a yield of 1S.3 bu. in each case. The general conclusions 

 drawn from this series of experiments are summarized in the following table: 



General effect of various fertiJizers on 3 years' yields of cereals at Davis. 



« Decrease. 



A table states the results of cooperative tests of superphosphate on oats, 

 wheat, and barley grown on various clay and loam soils. 



Drilling was followed by a yield of 6.37 bu. per acre of barley over broadcast 

 seeding. The wheat yield was similarly increased 3.25 bu. per acre or 10.3 

 per cent. Four years' tests indicate that wheat sown before December 20 

 produced 4.07 bu. per acre, or 10.14 per cent more than that sown after January 

 25. The barley yield was increased 14.89 bu. or 30.5 per cent. 



Many samples of common wheats about to be used for seed were sieve-graded 

 for comparison against a standard lot of the same variety and the results re- 



