72 BOARD OF AGRICULTURE. 



the season of growth. If we apply manure in the fall, we 

 then have a loss through leaching, because during the fall 

 and winter, on account of evaporation being checked by the 

 lowness of temperature and by the foliage of the plants not 

 respiring (being in a dead, inert state), we have a passage of 

 the water through our soil; so that there is a loss during 

 the winter season of the fertilizing constituents. 



During the warm and evaporating time, in summer, two 

 feet of surface-soil of the ordinary character will dispose 

 of seven or eight inches of rainfall, without showing any 

 drainage in leacliing. During the winter or late fall, when 

 evaporation is not as great, the soil will not hold more than 

 three or four inches, sometimes even less. So that you see 

 now a real reason for the doctor's advice to apply fertilizers 

 or dung in the spring ; or, if you apply them in the winter, 

 apply them after the land is frozen, and in those climates 

 where the land does not open during the winter. The num- 

 ber of inches varies with the temperature ; it varies with the 

 wind, with the quantity of water in the soil from previous 

 rains, and from various other circumstances. I simply state 

 that oftentimes the two feet of soil will contain or dispose of 

 seven or eight inches of rainfall, while at other times that 

 same soil will not contain more than two or three inches of 

 rainfall ; the difference being brought about by the difference 

 of the evaporation between summer and winter, and because 

 in winter we have no . respiration from the plants, which we 

 have largely in summer. 



Dr. Wakefield. I will ask the doctor if he finds any 

 constituents of fertilizers applied in the growing season in 

 the water leached through below where the roots of any 

 given crop would go. 



Dr. Sturtevant. I will only say that that opens the 

 whole question under discussion of the use of fertilizers, 

 and that question cannot be answered without bringing in a 

 great deal of collateral information. The elements of fertil- 

 ity which concern us as farmers are but three in number, — 

 nitrogen, phosphoric acid, and potash. These are acted 

 upon by the soil differently, and are acted upon differently 

 by different soils; and while phosphoric acid and potash, 

 speaking agriculturally, never leach from the soil, and sul- 

 phate of ammonia applied to the soil leaches but very slowly, 



