SURFACE APPLICATION. 199 



exposed to every variation of the season, has been 

 criticized. It is said to lose its volatile parts ; that 

 rain washes out and carries away those which are 

 soluble ; and, induced by these fears, many do not 

 spread the dung till the very moment when the 

 land is ready for the plough. This difference of 

 opinion in parties personally interested in making' 

 the most of their manure, ought not to be passed 

 over lightly. In agricultural matters it is danger- 

 ous to generalize too much. The climate ought to 

 be taken into consideration. In Alsatia, where the 

 rain during the whole year amounts to twenty-seven 

 inches, during December, January, and February, 

 the quantity amounts only to four inches and thirty- 

 six hundredths. The quality of the manure might, 

 perhaps, be injured when the proportion in winter 

 is greater. The quality of the manure itself must 

 also be taken into consideration, as a heap which 

 contains a large portion of carbonate of ammonia, 

 and emits a very decided odor of volatile alkali, 

 would certainly be deteriorated by prolonged expos- 

 ure to the air ; but this loss is scarcely perceptible 

 where the manure contains but a small quantity of 

 ammoniacal salts, as is the case with that which 

 has been treated with gypsum. When the rains are 

 not too heavy, the soluble part of the manure which 

 is spread over the land penetrates it, and is retained 

 in the upper stratum, exactly as when, instead of 

 incorporating the manure with the soil, it is spread 



