BULLETIN *700, U. S. DEPARTMENT OF AGRICULTURE. 



(2) Fertile clay loam. This was of tlie same general texture as the 

 less fertile soil, but owing to the presence of an adequate ' ground 

 cover the soil had not been subject to washing and erosion. It ap- 

 peared to be more mellow than the "infertile" clay loam and was 

 darker in color. 



The more important chemical properties at the time of the begin- 

 ning of the experiment were as follows: 



Soil 



Lime 

 (CaO). 



Infertile clay loam . 

 Fertile clay loam . . 



Per cent. 

 1.28 

 1.49 



Potash 

 (KjG). 



Phos- 

 phoric 



acid 

 (P2O5). 



Per cent. 

 1.53 

 1.30 



Per cent. 



0.22 



.33 



Total 

 nitrogen 



Per cent. 

 0.156 



.488 



Loss by 

 ignition. 



Per cent. 

 6.64 

 14.65 



/S 



/3 

 /2 



// 





2) 













1 







1 







^ 



1 



1 







', 









1 







^ 









1 



- 





'' 















', 











> 

















1 



\ 



1 



1 























1 







1 





1 











1 



1 











1 







IV, 



5 (t) 







p 1 





^ 1 

 * 1 







1 





/ 





1 ^ 





























> 1 







\ \ 





1 







i 1 









\ i 





1 



^eas 



S/~0/77Q_ 



WcLter re.qLu re.menl5 per un/'t of dry weJaht 

 ■■■ /nf&rti/e. so/ J 



l^/tear Aeac/s 



FerT/'/e. so/7 

 «■— "• Fer cent difference. 



Fig. 2. Relative water requirements per unit dry weight for peas, native brome grass, 



and wheat grown in infertile and in fertile soils of the same type. 



The chief difference chemically Avas in the total nitrogen content. 

 Also there was a wide difference in the humus content as determined 

 by incineration. The difference in the latter was largely responsible 

 for the contrast in the wilting , coefficients of the soils, this factor 



