The Journal of the Department of Agriculture, Victoria . ly,the value ofvarious heavy and lightdressings of super, onthe sheep carrying capa-city of the pasture hasnot been the subject ofsystematic and continuedexperiment in this State,and there is no local dataas a guide. In any case it is wellto remember that, evenif the value of the extrayield obtained fromheavy dressings merelycovers the increased costof the manure, it willpay to use the heavydressing, because thesoil is being enriched inphosphoric acid withoutextra cost. It may be thoughtthat, if more solublephosphates are applie
The Journal of the Department of Agriculture, Victoria . ly,the value ofvarious heavy and lightdressings of super, onthe sheep carrying capa-city of the pasture hasnot been the subject ofsystematic and continuedexperiment in this State,and there is no local dataas a guide. In any case it is wellto remember that, evenif the value of the extrayield obtained fromheavy dressings merelycovers the increased costof the manure, it willpay to use the heavydressing, because thesoil is being enriched inphosphoric acid withoutextra cost. It may be thoughtthat, if more solublephosphates are appliedthan are really necessaryfor a wheat crop, theexcess is lost for succeed-ing crops. Such, how-ever, is not the , unlike ni-trates, are not generallyfound in the drainagewaters. They becomefixed in the soil shortlyafter their explained above,soluble phosphates, whenapplied to the soil, be-come dissolved and inti-mately mixed with thesoil particles, and thenrapidly imdergo conver-sion into less solubleforms. In tliis manner. Journal of Agriculture, Victoria. [ii Nov., 1912. they are fixed in the soil and prevented from becoming lost. This isborne out by the investigations of Dyer in the permanent plots of the-Rothamsted experimental station. Dyers results show that practi-cally no loss of phosphoric acid has taken place on the plot heavily-manured with super, for over fifty years. It is often asked whether the continual use of superphosphate willimpoverish or exhaust the soil. Real soil exhaustion, of course, cannever take place. Bad farming practices, however, may reduce thefertility of the soil to such a low level as to render cropping operationsunprofitable. For practical purposes we say that such a soil is wornout or exhausted. Now, the repeated use of superphosphate will not bring about anysuch soil exhaustion, if the farm operations are intelligently continued use of phosphates will merely bring about a state ofthings in which fu
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