226 



SCIENCE 



[N. S. Vol. XXXIII. No. 841 



productivity is measured more by the effi- 

 ciency of its complex of activities than by 

 any mere measure of its inorganic con- 

 stituents. 



That the capillary cycle, a sub-factor of the 

 drainage cycle, is an important agency in 

 maintaining the supply of potash and phos- 

 phorus in the soils; that the selective action 

 of clays and of ferric oxides aid in a specific 

 way the concentration of potash and phos- 

 phorus surfaceward; that at 592 localities in 

 France analyses showed 68 per cent, of the 

 surface soils to be as high or higher in phos- 

 phoric acid than the subsoils, and 47 per cent, 

 as high or higher in potassium than the sub- 

 soils, and similar facts are observed in Amer- 

 ica;^ that the phosphate rocks in the sedimen- 

 tary formations are largely secondary concen- 

 trations; that the formation of ferric and 

 aluminic phosphates is a phase of eoncentra- 

 tive action; that some of the phosphoric and 

 potassic compounds are to be grouped with the 

 silica and the aluminic and ferric oxides as 

 the rock-elements that tend to stay in the soils, 

 while the compounds of soda, lime and mag- 

 nesia are more liable to go down to the sea, 

 and the carbon and nitrogen to go off into the 

 air; that these capillai^y and selective actions 

 jointly are efficient factors in productivity; 

 that Cameron's recent estimate* probably lies 

 in the direction of the facts of the case, 

 though confessedly only a tentative estimate 

 based on elements not fully determined at 

 present, viz., an annual drainage loss for the 

 area of the United States of about 3,500,000 

 tons of potassium and 1,200,000 tons of phos- 

 phoric acid (PO^) ; a possible crop-removal 

 (reckoned at 1 ton per acre for the entire 

 United States, carrying 1 per cent. K, and 

 0.6 per cent. PO,) of 24,000,000 tons of K and 

 14,000,000 tons of P0„ while, on the other 

 hand, the capillary waters are carrying toward 

 the surface 48,000,000 to 100,000,000 tons of K 

 and 18,000,000 to 40,000,000 tons of PO,. 



That the plant-cycle cooperates with the 

 capillary cycle in concentrating potash and 



' Bureau of Soils, U. S. Department of Agricul- 

 ture. 



'Journal of Physical Chemistry, 1910. 



phosphorus toward the surface by carrying 

 these up into the plants whence they are 

 deposited on the surface or in the soil; 

 that the well-known rotation of legumes and 

 cereals that enriches the soil in nitrogen may 

 be supplemented by a long-period rotation of 

 trees and annuals for the enrichment of the 

 soil in potash and phosphorus. 



That the capillary cycle and the plant cycle 

 conjointly contribute to a potash cycle and a 

 phosphorus cycle by which these rise from the 

 depths, pass into the plants, are shed as leaves, 

 fruit and dead fiber on the surface — or pass 

 through animals and are ultimately deposited 

 on the surface — thence reenter the soil and are 

 again taken up by plants, and so continue in 

 the cycle until some intervening agency bears 

 them out of it ; that the length of this cycle is 

 indeterminate and, in the absence of inter- 

 vention, theoretically indefinite; that it is not, 

 in the main, the material substance of the soil 

 that is needed for food but the energy locked 

 up in the grains, fruits, and so forth, by the 

 anamorphic processes of the plants; that the 

 real food comes chiefly from the sun and the 

 material substance that temporarily embodies 

 it is returnable to the soil indefinitely to be 

 used again and again; that the really vital 

 thing is the promotion of the cycle formed by 

 plant anamorphism (solar energy going in) 

 and animal katamorphism (solar energy com- 

 ing out) ; that the contingencies of loss lie 

 chiefly in the removal of the katamorphic 

 products before they again enter into a new 

 anamorphic process, contingencies that man 

 emphasizes. 



That the SzeChuanese of West China, 

 occupying a hilly sub-mountainous sandstone 

 region whose area is less than that of Texas, 

 a people numbering 68,724,800 according to 

 the Chinese census, embracing more farmers 

 probably than does the entire United States, 

 have cultivated their soils continuously from 

 an undetermined date before the beginning 

 of the Christian era and quite without rock 

 phosphates apparently, and yet have main- 

 tained a productivity exceeding, area for area, 

 that of the virgin soils of America; that with 

 little doubt this fertility can be maintained 



