plants 01 m & * ne Pl an t fd n t merely solubility in water, but 

 - solubility in soil waters as well. Fertilizer substances 

 S freely soluble in water are generally of the highest 

 quality, yet there are differences even in this. For 

 example, Nitrate of Soda is freely soluble in soil liquids 

 and water, and is the highest grade of plant food Nitro- 

 gen ; sulphate of ammonia is also soluble in water, but of 

 distinctly lower quality because plants always use Ni- 

 trogen in the Nitrate form, and the Nitrogen in sulphate 

 of ammonia must be Nitrated before plants can make 

 use of it. This is done in the soil by the action of 



certain organisms, under favorable con- 

 Defects and ditions. The weather must be suit- 



Us^of Ordinary & kl e > the soil in a certain condition ; and 

 Nitrogens. besides, there are considerable losses 



of valuable substance in the natural 

 soil process of Nitrating such Nitrogen. By unfavor- 

 able weather conditions, or very wet or acid soils, Ni- 

 tration may be prevented until the season is too far 

 advanced, hence there may be loss of time, crop and 



money. The quality of nitrogens, such 

 Intrinsic Values as cotton-seed meal, dried fish, dried 



blood, and tankage, is limited by condi- 



Nttrateas the tions similar to those which limit sul- 

 Standard. phate of ammonia. With these sub- 



stances, the loss of Nitrogen in its 

 natural air and soil conversion into Nitrate is very great. 

 Perfectly authentic experiments, and made under 

 official supervision, have shown that 100 pounds of 

 nitrogen in these organic forms have only from one-half 

 to three-fourths the manurial value of 100 pounds of 

 Nitrate of Soda. 



Special Functions of Plant Food. 



As stated before, plants must have 

 Unusual a u tnree o f tne plant f ood elements Ni- 



Nttrate ni trate '. Ph sphates and Potash but 



notwithstanding this imperative need, 

 each of the three elements has its special use. There 

 are many cases in which considerations of the special 

 functions of plant food elements become important. 



