EXPERIMENTAL WOEK WITH EAW ROCK PHOSPHATE. 



79 



Table XLV. — Average yields of corn, oats, wheat', clover, cowpeas, and oat hay 

 in an 8-year experiment at Hurdland, Mo. (1907-1914). 



Fertilizer. 



Application per acre. 



Com 

 8 crops. 



Oats, 

 6 crops. 



Wheat, 

 6 crops. 



Clover, 

 3 crops. 



Cow- 

 peas, 

 1 crop. 



Oat 

 Hay, 

 1 crop. 



Legume 



' Do 



Bone meal 



Legume 



Bone meal 



Lime 



Legiune 



Bone meal 



Lime 



Potassium cholride. 



No treatment 



Manure 



Do 



Roelc phosphate 



Manure 



Rock ph osphate 



Legume 



150 pounds > 



150 pounds 1 

 1 ton2. 



150 pounds 1 

 1 ton 2 



50 pounds 1. 



8 tons 3 



S tons 3 



1,000 pounds 3 . 



8 tons 3 



1,000 pounds 3. 



Bushels. 

 29.3 



29.3 



33.1 

 41.6 

 40.4 



Bv-shels. 

 27.9 



35.2 



26.9 

 31.6 

 32.0 



Bushels. 

 14.4 



13.7 

 17.7 

 17.2 



Pounds. 

 2,500 



3,775 



4,116 



2,741 

 3,341 

 3,241 



Pounds. 

 3,850 



7,150 

 5,850 



6,100 



4,200 

 3,525 

 5,450 



4,150 



Pounds. 

 3,850 



4,150 

 4,650 



2,200 

 3,225 

 3,700 



3,500 



1 Applications made every two years. 



2 Applications made every six years. 



3 Applications made every four years. 



In the Hurdland experiment the addition of phosphate rock to 

 manure seemed to have little effect, except in the case of cowpeas and 

 oat liay, where the yields were considerably greater than on the plots 

 receiving manure alone. Bone meal also seemed to be more effective 

 on these same crops, but as in the case of the other experiments the 

 data are such that no rigid conclusion can be drawn from a compari- 

 son of the results as to the relative value of the two forms of phos- 

 phoric acid. 



The fourth experiment, similar in most respects to the three just 

 described, is being conducted near Laclede, Linn County, Mo. The 

 last published report^ gives the results obtained after eight years' 

 work in a four-year rotation of corn, oats, wheat, and clover (sub- 

 stituting cowpeas when the latter crop failed). 



The field is located on gently rolling prairie land. The soil is the 

 typical Shelby loam, which consists of a dark-brown loam to fine 

 sandy loam, changing at a depth of about 10 inches to a light-brown 

 or grayish-brown loam. The subsoil below 18 inches is a light-brown 

 stiff sandy clay. According to the analysis the phosphoric acid and 

 nitrogen content of this soil was rather low. The field was laid out 

 in four tracts, each tract being subdivided into eight plots, as in the 

 case of the three experiments just described. The fertilizer applica- 

 tions were the same as in the Hurdland experiment. 



The results of eight years' work on the Laclede field are given in 

 Table XLVI. 



iMo. Agr. Expt. Sta., Bui. No. 128, pp. 388-394 (1915). 



