272 SYSTEMS OF PERMANENT AGRICULTURE 



ing vegetable matter, and for such crops as certain legumes, Indian corn, millet, 

 and possibly wheat and oats, which seem far better able to make use of them 

 than certain vegetables." 



In Tables 440 and 4$c are recorded the results obtained in the 

 continuation of these Rhode Island experiments, with soy beans in 

 1902, with nineteen different kinds of plants in 1903 (varying from 

 i row of spinach and 2 rows of lettuce to 10 rows of barley and 16 

 rows of oats), and with oats in 1904. 



The heavy applications made in the spring of 1902, amounting 

 to 1426 pounds of acid bone black, 1738 pounds of acid bone meal, 

 and 1771 pounds per acre of acid phosphate, with no additional 

 application of raw calcium phosphate, render the subsequent crop 

 yields of less economic importance, in the author's opinion, but 

 they are of interest because of the great variety of plants repre- 

 sented, although the data are not sufficient to justify very definite 

 conclusions. 



The following comments on the results of 1902, 1903, and 1904, 

 are given in Rhode Island Bulletin 118, page 84: 



"Floats (raw calcium phosphate) gave very good results with the soy beans, 

 peas, crimson clover, mangel-wurzel (on limed land), barley (on limed land), 

 potato (on unlimed land), Japanese millet, oats, and golden millet; but they 

 proved highly inefficient, especially for Hubbard squash, rutabaga, crookneck 

 squash, flat turnip, cabbage, mangel-wurzel (on the acid unlimed land), 

 tomato, lettuce, New Zealand spinach, and red valentine bean." 



One of the oldest known facts concerning plant nutrition is the 

 weak power of turnips and other plants of the cabbage family 

 (Crucifferae) to secure phosphorus from insoluble forms. Thus, 

 almost the first important result of Sir John Lawes' agricultural 

 experiments was the discovery, seventy years ago, that dissolved 

 bone black was very much more efficient than the untreated ma- 

 terial for the production of turnips. 



In no case in the Rhode Island results for 1902, 1903, or 1904, 

 with soy beans, crimson clover, millet, or oats (representing the 

 farm grains, grasses, and legumes) was the increase from acid phos- 

 phate double the increase from raw calcium phosphate, and as an 

 average of the results with these crops (on limed or on unlimed 

 plots) the increase from acid phosphate was not more than i| 

 times that from the raw calcium phosphate, although the cost of 



