GUANO AND SULPHURIC ACLJ. 



253 



of ammonia, which slowly sinks into the ground, and 

 all parts of the soil with which the solution comes in 

 contact are enriched at the same time with phosphoric 

 acid and ammonia. If to the saw-dust, turi-dust, &c., 

 gypsum is added, it decomposes with the phosphate of 

 ammonia into very finely-divided phosphate of lime and 

 sulphate of ammonia, which are separated by the rain 

 water ; the soluble sulphate of ammonia penetrating 

 deeper into the ground and carrying down with it a 

 small quantity of the phosphate of lime, whilst the main 

 bulk of the latter is left on the top. 



On land poor in potash, the addition of wood ashes 

 to the guano, moistened with water and sulphuric acid, 

 will be found beneficial, as the carbonate of potash de- 

 composes with the phosphate of ammonia into carbonate 

 of ammonia and phosphate of potash, and the potash 

 does not interfere with the phosphoric acid penetrating 

 into the soil. 



The results obtained, in the Saxon experiments, by 

 manuring with guano, afford a clear insight into all the pe- 

 culiarities observed in the action of this manuring agent. 



If we compare the produce severally obtained by 

 manuring with guano and with farm-yard manure (see 

 page 186), we are led to the following considerations on 

 the condition of the experimental field : 



Manuring with guano. 



