214 CHEMICAL FERTILIZERS 



magnesia produced far greater results than they did in the 

 dry year of 1893, whilst sulphate of potash was rather better 

 in the dry year than in the wet year. The ammonia com- 

 pounds come out very well in the abnormal years. In a wet 

 season, when there is plenty of water, the farmyard manure 

 loses its pre-eminent position, so that many forms of artificial 

 manures are equal to, and sometimes superior to, farmyard 

 manure. On the other hand, during the dry years farmyard 

 manure easily heads the list. With wet climates and open 

 soils, soluble manures very easily wash away, and it is hence 

 necessary to supply these at intervals as top dressings. Dry 

 climates with retentive soils lose very little, and the 

 soluble manures are not easily lost. On the other hand, it 

 cannot be said that the light soils with dry climates particu- 

 larly need the less soluble fertilizers. Where both soil and 

 climate are dry, it is necessary to use soluble fertilizers to 

 economize the water that is so deficient. 



REFERENCES TO SECTION III. 



Russell, " Waste Land and Agriculture," Journ. Soc. Chem. Ind., 1917, 

 p. 1251. 



Cowie, " Decomposition of Cyanamide and Dicyanodiamide in the Soil," 

 Journ. Agric. Science, April, 1919, p. 113. 



Bernard Dyer, " Available Mineral Plant Food," Journ. Chem. Soc., 

 1894, p. 115. 



Somerville, " Poverty Bottom," Journ. Board Agric., 1917-18, p. 1186. 



Webberley, " Farming on Factory Lines," p. 54 (Pearson). 



Clouston, " Artificial Fertilizers for Cotton," Agric. Journ. India, 1908, 

 p. 246. 



Bald, " Experiments in Manuring on a Tea Estate," Agric. Journ. India, 



1913, P- J 57; 1914, P- l82 - 



Russell, "Artificial Fertilizers: their Present Use and Future Prospects, 

 Journ. Soc. Chem. Ind., March, 1917, p. 252. 



Hall, " The Book of the Rothamsted Experiments," pp. 57 and 292 

 (Murray). 



