228 
Journal of Agricultural Research 
Vol. XXIII, No. 3 
From these analyses of the solutions it will be observed that the lime- 
water extraction contained no iron or aluminum and only a very small 
quantity of manganese, while the potash was much higher in the lime- 
water extraction than in the carbon-dioxid solution. It can therefore 
be assumed that the carbon dioxid of the soil water, in connection with 
the acid secretion of the roots, would be amply sufficient to bring the 
toxic elements into solution and that a sufficient quantity of lime would 
inhibit this action. 
Pot cultures were also made to test the effect of the toxic greensand, 
the soluble salts, the glauconite, and the greensand when used with the 
addition of lime. The accompanying illustrations show very strikingly 
the effect in each case. 
Plate i, A, shows com seedlings 6 weeks old grown in quartz sand to 
which had been added glauconite from the Courtland greensand at the 
rate of io tons per acre, and Plate i, B, shows the effect of the greensand 
with most of the glauconite removed. 
Plate 2, A, shows the effect of the alkaline medium, principally salts of 
calcium, sodium, and potassium, from the washings of the Courtland 
greensand, at the rate of 3 tons per acre, and Plate 2, B, the effect of the 
heavy metals, principally magnesium, iron, aluminum, and manganese, 
obtained from the Courtland greensand by extracting with water made 
slightly acid with hydrochloric acid, but free from lime, applied at the 
rate of 2 tons per acre. To this there was also added a liberal applica¬ 
tion of Shive’s nutrient solution. 4 
Plate 3 shows the effect of the toxic greensand when used alone and 
in combination with lime carbonate at the rate of 4 tons per acre. 
A comparison of Plate 1, A, with Plate 2, B, and Plate 3, A, shows 
that the glauconite, heavy metals, and toxic greensand had practically 
the same toxic effect, while Plate 2, A, and Plate 3, B, show the very 
favorable effect of the addition of lime. It seems probable, therefore, 
that the toxic properties of this poisonous greensand may be overcome 
by using liberal applications of lime, thereby keeping out of solution 
the three poisonous elements, iron, aluminum, and manganese in toxic 
concentrations and rendering useful the potash which is readily available 
and which is greatly needed in many localities. 
SUMMARY 
The glauconite element from each of the three deposits of greensand 
studies was found to be toxic to com seedlings. 
The toxicity is due to the presence of iron, aluminum, and manganese 
in forms readily soluble in weakly acid media. 
The presence of lime prevents the toxic elements from going into 
solution. Therefore, deposits of greensand like those at Newcastle, Va., 
and at Redbank, N. J., which naturally contain lime in the form of shell 
marl in sufficient quantity to prevent the solution of the toxic elements 
are not poisonous to plants. Likewise the addition of lime to the toxic 
Courtland greensand inhibits its toxic effects. 
4 SmvE, John W. a Three-salt nutrient solution for plants. In Araer. Jour. Bot., v. 2, no. 4, p. 
137-160. 1915. 
