NITRATE OF SODA. 67 



brought almost immediately to the open mouths of piants, 

 and thus by absorption they are stimulated to growth when 

 growth is not desirable. 



A plant is not benefited if it is fed just before frosts are 

 ready to cut it down and arrest all activity. Beside this, the 

 application of active fertilizers in the fall is attended with 

 loss in other directions. Substances like nitrate of soda and 

 potash, and chloride of potassium, are quite soluble ; and the 

 liquid is apt to run away if facilities are afforded. If applied 

 to a side hill late in autumn, when a glaze of ice is possible, 

 almost a total loss may result, if a brook receive the wash- 

 ings of the hills. On porous, absorptive soils the dissolved 

 salts may sink too deep into the soil during a long winter and 

 early spring. Our method has been to apply chemical fertil- 

 izers to grass-lands in the spring, not too early, just before 

 growth begins. Results have been highly satisfactory in all 

 cases. Farmers must remember never to apply nitrate of 

 soda alone or uncombined. This salt aids greatly in the 

 growth of the rich grasses ; but, if applied by itself, it may 

 do harm. Combine it always with good super-phosphate, and 

 then its maximum effects are seen. We are certain that this 

 important fact is not well understood: it is a fact learned by 

 deduction and experience. No one of the active agents of 

 plant-food does well alone, save, perhaps, super-phosphate, 

 and this benefit is largely confined to root-crops.. As soon 

 as farmers understand how to use and when to use the con- 

 centrated fertilizers as top-dressings to grass-lands, these will 

 be much more extensively eraploj'ed than at present. 



Chemistry has done much for the new agriculture ; but in 

 some directions it has done less than was anticipated at the 

 period when the more exact methods and processes were first 

 understood. It was anticipated, that, in soil analysis, chemis- 

 tr}" would render its most distinguished aid ; but such antici- 

 pations have not been realized. Soil analysis is the most 

 uncertain and perplexing work which the chemist is called to 

 perform ; and, we may add, the practical difficulties are so 

 great in the work, that the results are usually not very satis- 

 factory. Let me examine these difficulties for a moment, or 

 endeavor to bring them more directly to your attention. If a 

 given soil is valuable from the amount of nitrogen, phos- 

 phoric acid, and potash, which it contains, it is important that 



