MINERAL NUTRIENTS AND NITROGEN 207 



2. Crone's Solution. 



Potassium nitrate 1.00 gram 



Ferrous phosphate 50 gram 



Calcium sulfate 25 gram 



Magnesium sulfate 25 gram 



Distilled water 2.00 litrea 



These soliitions can be varied by the removal of certain 

 compounds and some idea obtained as to the exact needs of 

 the plant. 



If glass jars are used, they should be covered with black 

 paper to prevent the growth of algae, which will interfere with 

 the experiments. 



Since the plants will use these minerals the solutions should 

 be changed frequently. 



Balanced Solutions. — It is very generally recognized that 

 any nutrient salt used alone may prove injvirious to plant growth. 

 It is also well kno-wn that the nutrients in a solution or soil must 

 bear a definite relation in order to secure the most satisfactory 

 plant growth. In recent years it has been learned that the 

 injurious effects of some of these nutrients may be overcome by 

 the use of others. Solutions in which these antagonistic 

 nutrients are properly mixed in order' to give good results are 

 known as " balanced solutions." The magnesium, compounds 

 are toxic to most of our higher plants, but this toxicity can be 

 overco'me by the proper use of lime. Therefore, when soils 

 contain an abundance of magnesia, it is usually necessary to 

 use lime, bat care should be taken to use a grade of limestone 

 relatively free from magnesia. It will be readily seen that a 

 knowledge of balanced solutions becomes a very iniportant factor 

 in the stu-dy of fertilizers. 



