BUREAU OF PLANT INDUSTRY. 197 



PLANT-FOOD REQUIREMENTS OF IMPORTANT SOIL TYPES. 



Large areas of certain soil t3^pes of the United States are devoted 

 to important croi)> for Avhicli they are particuhirly adapted, and fer- 

 tilizer studies on these important types to determine the plant-food 

 requirements of tlie principal crop grown on the type are an im- 

 portant phafcc of the investigations in soil fertility. With a small 

 beginning in 1910 on a single soil tyi)e, the work has grown steadily 

 in scope and importance, and the demand for its extension has been 

 such that it now covers large soil regions in the Atlantic Coast States 

 and is encompassing regions lying farther inland. Cooperative field 

 experiments are now in progress in Maine on the Caribou and AV ash- 

 burn loam : in New York on the Sassafras loam ; in Ncav Jersey on the 

 Penn loam and Sassafras sandy loam; in Pennsylvania on the Ha- 

 gerstown loam; in Virginia on the Norfolk fine sandy loam; in North 

 Carolina on the Duni.ar fine sandy loam and Portsmouth sandy 

 loam ; in South Carolina on the Norfolk fine sandy loam and coarse 

 sandy loam, Ruston coarse loamy sand, Portsmouth sandy loam, and 

 Coxville fine sandy loam: in Georgia on the Cecil sandy loam, 

 Orangeburg sandy lonm, Greenville sandy loam, Susquehanna and 

 Norfolk fine sandy loam ; in Florida on the Norfolk sand and fine 

 sandy loam and Orlando fine sand; in Indiana f)n the Scottsburg silt 

 loam ; in Wisconsin on the vSuperior silty clay loam ; in Arkansas on 

 the Pope fine sandy loam. The crops grown are the main crops of 

 the regions, representing millions of dollars of agricultural wealtli 

 and comprising potatoes, cotton, and corn, the leading mone}^ crops 

 of the country, as well as pecans, grass, clover, sorghum, celery, let- 

 tuce, etc. The results very clearly show the difference in fertilizer 

 requirements on the different tj-pes, some responding more readily 

 to nitrogen than to potash or phosphate, while others show a decided 

 deficiency in phosphate or in potash. In each case the best ratio of 

 nitrogen, phosphate, and potash is determined, and the results are of 

 great economic and practical value to the growers in the regions con- 

 cerned. This use of the proper formula or ratio in plant foods is 

 made of more and more importance l)ecause of the constantly in- 

 creasing cost of the fertilizing materials. It has thus been possible 

 to make recommendations which have resulted in the saving of thou- 

 sands of dollars to the groAvers in the purchasing of properly balanced 

 fertilizers. 



NEW FERTILIZER MATERIALS. 



A study has been made of cyanamid and other nitrogen sour es 

 derivable from this product of nitrogen fixation, and the results ob- 

 tained are serving as a guide in further pursuing this subject in the 

 Government's nitrogen-fixation plants. It has been found that cyan- 

 amid in mixtures of fertilizer materials undergoes changes into other 

 compounds, some of which appear to he much less available to plants 

 and in some' cases even distinctly harmful, so that careful .sujier- 

 vision and control to ])revent these transformations are necessary. 

 Many other new fci-tilizer materials which have been brought foi-- 

 ward as a result of the changed conditions that occui- in the fer- 

 tilizer materials industry have been studied. ^lany of these are 

 legitimate sources of new fertilizing materials, but a great many 

 have shown themselves to be of more or less doubtful value an<l in 



