14 PRINCIPLES OF AGRICULTURAL CHEMISTRY 



The non-metals: carbon, hydrogen and oxygen, secured from 

 the air and water, as already stated, are essential. A soil, to be 

 fertile, must supply to the plant an abundance of potassium, 

 calcium, magnesium, iron, nitrogen, sulphur, and phosphorus. 



Plants can be grown to full maturity by means of the follow- 

 ing solution: 



One gram calcium nitrate, 



0.25 gram potassium nitrate, 



0.25 gram potassium sulphate, 



0.25 gram magnesium sulphate, 



0.20 gram ferrous phosphate. 



1,000 cc distilled water. 



Chlorine Essential but Unimportant. Experiments to ascertain 

 whether or not chlorine is essential to plants were at first con- 

 flicting. Three independent investigators grew plants in water 

 culture to full and complete maturity without chlorine. Knop 

 grew corn, buckwheat and cress ; Wagner grew corn ; and Birner 

 grew oats. 



On the other hand, Nobbe and Siegert 1 found that, although 

 buckwheat grew- well in water culture without chlorine up to the 

 time of flowering, a little later the tips of the stalks died off, the 

 leaves became brittle, spotted, and fluffy, starch accumulated in 

 the stems and no seed were produced. The diseased condition 

 was remedied by the addition of chlorine. Chlorine thus appear- 

 ed to be essential to the formation of the seed of buckwheat. 

 Leydhecker 2 also found that buckwheat would not seed in absence 

 of chlorine, and Nobbe later confirmed previous results by a sec- 

 ond series of experiments. 



Thus one group of investigators finds chlorine not essential, the 

 other group finds that it is essential. These contradictory results 

 are explained by the work of Bayer. 3 Bayer grew oats in water 

 culture, with and without chlorine, all the other essential elements 

 being, of course, present. With chlorine 12.5 grams seed were 



1 Landw, Vrersuchs-stat. , 1863, p. 116; 1865, p. 377. 



2 Ibid, 1866, p. 177. 



3 Landw. Versuchs-stat., 7, p. 370. 



