96 CIVIC BIOLOGY 



tearing off half the roots of the corn plants for centuries, 

 and laboriously reducing the yields from 30 to 50 or more 

 l)ushels per acre, some one hit upon the idea of studying — 

 applying '' cultivated thouglit •' to the roots of the single corn 

 plant. It was discovered that many of them spread out near 

 the surface, live, six, or even seven feet in every direction. 

 Next came the thought. May not too deep cultivating hi jure 

 these roots ? The experiment has now been tried of shaving 

 the weeds without stirring the soil at all, applying careful 



Fig. 48. l^vo plots of, corn on peaty swamp land 



Lfft, fertilized with phospliorus (not needed) : erop. 0. Right, fertilized Avith 



potassium: erop, 72 bushels per acre. Seed, cost of fertilizer. ;uid lal)or on the 



two plots about equal. Photograph by Cyril G. Hopkins 



shallow tillage to comparable rows in the same fields. Results 

 have shown, on the average, equal yields from the uncultivated 

 rows. Figure out, for your farm, township, county, state, or 

 for the United States, how manv dollars' Avorth of labor this 

 one discovery may save annually. 



Pure-bred selected strains. Again, we have learned that l)y 

 breedhig and selection of productive strains the crop may be 

 increased without additional labor. This fact gives the added 

 value to pure-bred stock in animals and plants. Half the plants 

 in an ordinary field of potatoes or corn may l)e ''loafers"; half 

 the trees in an ordinary orchard may be '' resters " ; half the 



