Feb. II. 1918 Effect of Season and Crop Growth on Soil Extract 



347 



sSO//. ^y^ 



^e2^ts^^^^_ 





I ^^ I i 1^ 1^ 1^: i 



^ ^l >| ^ ^1 ^1 ^1 ^^ 

 Fig. 12.— Graphs of the seasonal 



studies of the water extract of soil 5, Yolo silty clay loam. 



