BAVAIUAX KXPERIMENTS. 



147 



that tlie greater portion of tlieni in the soil was ineflectivc, 

 and that its power of production had depended chiefly 

 upon the supply of manure. Thus it arises, that while 

 some fiirmers believe that all manure can be dispensed 

 with because tillage alone is enough to render a field ]iro- 

 ductive, others suppose that the field can be kept fruitful 

 only by manuring. All these views are based upon indi- 

 vidual cases and have no general application ; for neither 

 one nor the other of the contending parties have any clear 

 knowledge of the true causes upon which the power of 

 production of this kind is founded. 



In the experiments made in the year 1857, by order 

 of the General Committee of the Bavarian Agricultural 

 Union, on the action of phosphorite upon certain fields at 

 Schleissheim deficient in phosphoric a»cid, the following 

 crops of summer wheat were reaped from two plots of 

 ground, one unman ured the other dressed, per hectare 

 (= 2^ acres), w4th 241-4 kilogrammes (= 530 lbs.) of phos- 

 phoric acid, 657-4 kilogrammes ( = 13 cwt.) of phosphorite 

 decomposed by sulphuric acid : — 



From a chemical analysis made by Dr Zoeller, of the 

 Munich Laboratory, the soil of this field was found to 

 give up to cold hydrochloric acid a quantity of phosphoric 

 acid, which, calculated per hectare to a depth of 25 

 centimetres, amounted to 237G kilogrammes = 5170 

 kilogrammes of pliosphate of lime. 



L 2 



