152 Principles of Plant Culture. 



available as plant food. Xitrate of potash (saltpeter) is 

 a most valuable fertilizing material, since it contains 

 both potash and nitrogen, but unfortunately its price is 

 too high to permit its use for this purpose. The muriate, 

 either pure or in crude form (kainit), and sulfate may, 

 on the other hand, be purchased at reasonable prices. 

 The sulfate is considered preferable for tobacco and pota- 

 toes as it is thought to produce a better quality of pro- 

 duct. The muriate acts more promptly than the sulfate, 

 however. 



265. Wood Ashes are a Valuable Fertilizer, especially 

 when unleached, as they contain both potash and phos- 

 phoric acid. In leaching, the potash is mostly washed 

 out, but the phosphoric acid is largely retained. Ashes 

 contain no nitrogen. 



266. Farm and Stable Manures should be the first de- 

 pendence of the cultivator. Aside from these, legumin- 

 ous crops (260) are undoubtedly the cheapest source of 

 nitrogen for the farm, and with unleached wood ashes, 

 furnish all the needed fertilizing ingredients for grain 

 crops grown in rotation. For garden crops, however, if 

 sufficient stable manure can not be obtained, more nitro- 

 gen may often be profitably used than can be furnished 

 by leguminous crops, hence for these, commercial fertil- 

 izers may often be added with advantage. 



267. Crops Suggest Their Own Needs to some extent, so 

 long as they are not suffering from drought. As a rule, 

 a lack of nitrogen is indicated by pale- green foliage or 

 small growth of leaf or stalk. Excess of nitrogen is 

 indicated by very large growth of leaf or stalk, with 

 imperfect bud-, flower- and fruit development. Lack of 



