

JOimOFAGRKETDRALlSEARCH 



Voiv. XV Washington, D. C, December 2, 1918 No. 9 



EXPERIMENTS ON THE VALUE OF GREENSAND AS A 

 SOURCE OF POTASSIUM FOR PLANT CULTURE 



By Rodney H. True, Physiologist in Charge, and Fred W. Geise, Scientific Assistant, ^1^^ 



Drug-Plant, Poisonous-Plant, Physiological, and Fermentation Investigations, Bureau ^f' w ^^ 

 of Plant Industry, United States Department of Agriculture "i'jy- ^^i[ 



HISTORICAL INTRODUCTION "^^^hN 



The practice of applying to farm lands deposits known under the 

 broad term "marl" has a long history both in Europe and in America. 

 Among those deposits occurring in the Atlantic coastal region from New 

 Jersey to Virginia are the so-called "greensands" which soon after the 

 American Revolution came into extensive use as fertilizers. These 

 greensands were sometimes found as relatively pure glauconite, but 

 perhaps oftener contained more or less abundant quantities of fossil 

 shells. The lime component was frequently sufficient to give to these 

 deposits the character of real marls. 



Analyses of New Jersey greensands made by Seybert * in 1822 showed 

 that iron, silica, and potash are present in pure greensand. Samples of 

 greensand marl were found to contain in addition varying quantities of 

 lime, phosphates, and other constituents. The value of these deposits 

 as fertilizers was variously ascribed by different investigators to the 

 lime, the iron, and the phosphates present. Since, however, it was not 

 definitely determined until the early sixties that potassium is necessary 

 for plant growth, the presence of this element could be only suspected 

 to have connection with the valuable properties observed. 



That great gains were seen in crops following the application of green- 

 sands and of greensand marls was the usual experience, and the practice 

 of "marling" during the quiet winter months became the rule in those 

 parts of New Jersey and Virginia in which the deposits were easy of 

 access. This practice grew to very great proportions in a number of 

 regions, railroads even being built in New Jersey to haul marl from pits 

 yielding a product of high reputation out into the adjacent country. 



The digging and carting of these heavy deposits, however, was a 

 severe drain on labor, and when in the sixties concentrated soluble 



1 Seybert, Henry, analysis op the green earth from rancocas creek, new jersey. In Mem. 

 Phila. Soc. Prom. Agr., v. 5, p. ai. 1826. 



Journal of Agricultural Research, Vol. XV, No. 9 



Washington, D. C Dec. 2. 1918 



qk Key No. G-172 



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