Soluhlc Coiisfitat'iifK ill All a rial Soil. Oo 



The amount of uiamirf added represents 0.28 ^rain i>er kilo- 

 pram of the superficial '_' iiahes. and the hii^h soluljility explains 

 the high iuaiount of water-soluble matter in the superlicial layers 

 on May 18. At the same time the superphosphate seems to 

 exercise a stronu; solvent action on the soil itself, of such 

 character as to strongly increase the amount of matter soluble 

 in dilute acid. The net result is to leave the soil distinctly 

 poorer in matter soluble in dilute acid than any of the previous 

 plots, but if this matter is utilised l)y the crop it represents a.n 

 increased yield and profit instead of so much inert material. Un- 

 fortunately Imt little appeared in the crop as ash, so that super- 

 phospliates by themselves appear to be highly wasteful and exhaust- 

 ing. If these facts hold good for soils in general, the exclusive use 

 of phospliates in Victorian agriculture is likely to rapidly exhaust 

 the fertility of the soil, not only because of the greater demands 

 of the increased crop, l)ut also because the superphosphate exercises 

 a secondary action on the soil, temporarily increasing the amount 

 of water-soluble matter and ako that of materials soluble in 

 very dilute acid. The former are rapidly and the laitter slowly 

 removed from the soil by the action of rain water charged with 

 carbon dioxide as well as by the crop. 



May 18 Sept. 25 Dec. 20 



Plot4-Gypsum Surface 5.2 (4.08) 4.0i (3.68) 4.2 (3.6G) 



(One ton per acre) H inches 4.4 (3.67) 3.9 (3.18) 3.5 (2.78) 



Ifi inches 4.15 (3.o(3) 3.4 (2.29) 3.1 (2.19) 



Average 4.58 (3.77) 3.78 (3.05) 3.6 (2.88) 



Ma\ 18 Sept. 25 Dec. 20 



Plot -No Manure Surface 3.32(3.01) 3.9 (3.72) 4.58(4.09) 



S inches 3.90 (3.42) 3.4 (3.05) 3.44 (2.96) 



16 inches 3.82 (3.34) 3.7 (3.02) 3.06 (2.65) 



Average 3.68 (3.26) 3.7 (3.26) 3.69 (3.23) 



Not only did the gj'psum produce a less crop yield than the 

 unnutnured plot and unduly increase the amount of water- 

 soluble niiUerial liable to waste by drainage, but it also ca.used 

 a pronounced decrease in the amount of acid-soluble material 

 by the end of the year. In the unmanured plot the averages 

 remain very nearly constant in spite of an increase towards 

 the surface and a decrease in the deeper layers. 



