BULLETIN 700, U. S. DEPARTMENT OF AGRICULTURE. 



(2) 1 Fertile clay lcam. 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 



Goil. 



Lime 

 (CaO). 



Potash 

 (K 2 0). 



Phos- 

 phoric 



acid 

 (P 2 5 ). 



Total 

 nitrogen . 



Loss hy 

 ignition. 





Per cent. 

 1.23 

 1.49 



Per cent. 

 1.53 

 1.30 



Per cent. 



0.22 



.33 



Per cent. 

 0.156 



.488 



Per cent. 

 6.64 





14.65 







/s 











' 



(V 



) 



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\ 













: 























































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—5 



K ■ 



4 1 













fv 













| 







VO 



15 











i I 



a N 





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i I 



i 







i 





1 



PecLS 



W/?ear Aeac/s 



Fig. 



Br-orr?e_ HZ/yeaf 



Wafer re.g cure. menls per un/tofdry weJafyt 

 wmm /nfert/'/e so// 

 w j>>>* FerT/'/e. so// 

 — • Fer cent d/fferenoe. 



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



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



The chief difference chemically was 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 



