FEETILIZERS. 725 



paleontolofjy of tlio Eocene depof^its, with an index. These deposits are of special 

 interest agriculturally, because they are larjrely f2;lauconitic and contain the most 

 extensive deposits of f^reensand marls. 



"The Eocene deposits of tlie Middle Atlantiir slope are typically glauctonitic, and 

 are found in thejr uuweathered state either as dark gray or green sands or claya. 

 The glauconite varies in amount from very nearly pure beds of that substance to 

 deposits in which the arenaceous and argillaceous elements predominate, although 

 tlie strata are generally very homogeneous through considerable thicknesses. At 

 certain horizons the shells of organisms are found conuiiingled with the glauconitic 

 materials in such numbers as largely to make up the beds, producing what is known 

 as a greensand marl. These beds are at times so indurati'd as to form true lime- 

 stone ledges." 



The report states that "two conditions are requisite for the formaliun of glauconite: 

 First, the deposition of mineral particles of land-derived origin; and second, the 

 presence of foraminifera. In the absence of either, glauconite will not be produced. 

 On the other hand, it is retarded and finally ceases altogether* as the amount of 

 deposition of land-derived materials increases adjacent to the coasts. Only, then, 

 within circumscribed limits, which are constantly subject to modification, is the 

 formation of glauconite possible. 



"Glauconite seldom, if ever, occurs pure in nature, but is mixed with greater or 

 less amounts of arenaceous materials, producing what is known as greensand, a term 

 which is commonly made to embrace the argillaceous deposits as well, particularly 

 when the glauconite grains are visible, although they are more correctly green clays. 

 When the deposits are distinctly calcareous they are generally known as greensand 

 marls. No definite percentage of any of the constituents is required, and as they are 

 so commonly intermingled the terms just described are used somewhat indiscrimi- 

 nately." 



FERTILIZERS. 



Pot experiments to test field observations concerning soil deficiencies, 

 B. L. Hartwell {Rhode Maud SUt. Rpt. 1001, pp. 274-29S, ph. ^).— This article dis- 

 cusses l)riefly the difficulty of accurately determining the available or assimilable 

 plant food in soils, maintaining that "analytical results have frequently failed to 

 account satisfactorily in the case of given soils for differences caused by known fer- 

 tilization and cropi)ing." This failure is stated to be " probably due in many cases 

 to the fact that the small amount of soil analyzed did not properly represent the 

 large areas from which it was taken." A well-conducted soil test is considered the 

 most satisfactory method of arriving at a knowledge of soil deficiencies, and it is 

 recommen<led that "soils designed for use as standards in testing methods for deter- 

 mining assimilable plant food should in many cases he first subjected to pot experi- 

 mentation." Pot experiments on oats during 2 years are reported with 1 soil 

 each from Massachusetts and Indiana, said to be deficient in assimilable phosphoric 

 acid, and 2 from Connecticut, supposed to be lacking in assimilable potash. The 

 pots used were of the Wagner type, 8 in. in diameter and 8 in. deep, holding from 

 13 to 16 lbs. of the different soils. The systems of manuring followed and the yields 

 of grain, straw, and entire crop are reported, as well as details of the method of 

 conducting the experiments. In the case of only one of the soils did the results of 

 the 2 years' experiments with oats agree fully with the field observations. It is sug- 

 gested that this may have been due to other factors aside from deficiencies of plant 

 food. For this reason it is recommended that "land upon which field experiments 

 are to be conducted for showing its need of i)lant food should first receive such treat- 

 ment, other than the application of the particular ingre<licnl to Ix- studied, as is 

 economical and necessary for the proper growth of most agricultural plants." 



