EXPEEIMENTAL WORK WITH EAW ROCK PHOSPHATE. 



81 



farmers continued their experiments for two years, the published 

 reports show that different fields were employed the second year. 



Three other series of field tests were published by the New Jersey 

 Station in 1913/ but none was conducted for more than 2 years, so 

 they do not warrant repetition. 



In 1913, however, the New Jersey station carried on two pot experi- 

 ments in cooperation with the basic slag committee of the Association 

 of Official Agricultural Chemists.^ The purpose of this investigation 

 was to test the availability of the phosphoric acid in basic slag in 

 comparison with other phosphates. Experiment No. 1 was conducted 

 in pots holding 20 pounds of clean white sand practically free from 

 any fertilizer elements. In experiment No. 2 pots were employed 

 holding 18 pounds of gravelly loam, poor in nitrogen and organic 

 matter, and containing about 0.07 to 0.08 per cent of PoOj soluble 

 in strong hydrochloric acid. Nitrogen, potash, iron, and sulphates 

 were supplied to each pot. The phosphates were applied in such 

 quantities as to furnish equal amounts of phosphoric acid, except 

 the ground raw rock which supplied twice the quantity of phosphoric 

 acid furnished by the other phosphates. Each treatment was run in 

 duplicate, except the checks of which there were four. The crop 

 grown was buckwheat which was harvested when the grain was be- 

 ginning to ripen. The results of these experiments are given below 

 in Table XLVII. 



Table XLVII. — Yields of buckwheat obtained in two pot experiments with pure 

 sand and with gravelly loam treated as outlined below. 



Fertilizer. 



Application - 

 per pot. 



Experiment No. 1. 



Weight 

 of crop. 



Increase 

 over checks. 



Experiment No. 2. 



Weight : Increase 

 of crop, over checks. 



No phosphate 



Acid phosphate , 



Sodium phosphate 



Basic slag A , 



Basic slag B , 



Basic slag C , 



Basic slag D 



Blue rock phosphate 



Double superphosphate. 

 No phosphate 



Grams. 



5.82 

 4.97 

 5.67 

 5.45 

 7.79 

 6.54 

 7.05 

 2.24 



Grams. 

 12.85 

 16.10 



3.30 

 14.15 

 16.50 

 14.95 

 15.35 



9.85 

 17.75 

 12.35 



Grams. 



13.50 

 .70 

 11.55 

 13.90 

 12.35 

 12.75 

 7.25 

 15.15 



Grams. 



124.10 

 30.35 

 29.65 

 31.15 

 35.20 

 27.80 

 33.35 

 24.40 

 31.70 



123.05 



Grams. 



6.77 

 6.07 

 7.57 

 11.62 

 4.22 

 9.77 

 .82 

 8.12 



1 Average of two pots. 



In experiment No. 1, where the crop was grown in pots containing 

 pure sand to which the same amounts of sodium nitrate, potassium 

 sulphate, etc., were added, the water soluble phosphates produced the 



IN. J. Agr. Expt. Sta., 34th Ann. Kept. (1914) ; 35th Ann. Eept. (1915). 

 'N. J. Agr. Expt. Sta., 34th Ann. Kept., 481-484 (1914). 



56841°— BuU. 699—18 6 



