62 The Bulletin. 



to be of use to the plant. It contains three parts lime and one part phosphate. 

 This rock is ground into a fine powder, treated with sulphuric acid, which acts 

 upon it in such a way as to take from it two parts of the lime, leaving one 

 part lime and the remainder water-soluble phosphoric acid. This is what 

 is known as acid phosphate, and is the most common source from which the 

 phosphoric acid used in making commercial fertilizers is derived. It is the 

 water-soluble phosphoric acid we are most concerned about. 



Nitrogen (ammonia, as it is known to most farmers) is the most expensive 

 element in all fertilizer, and it is that element we can most easily dispense 

 with buying. The atmosphere above our fields is more than three-fourths 

 nitrogen, and yet we are content to go ahead and buy it in the form of 

 fertilizer at 18 and 20 cents per pound, when by growing leguminous plants 

 in a proper rotation we could secure free of cost enough to furnish our plants. 

 Nitrogen as a commercial product is derived from various sources. Ammonia 

 is known as water-soluble or organic ammonia, which has reference to whether 

 it is readily soluble in water or whether it is first necessary to be decomposed 

 and decay before it gives off its nitrogen. The common forms of nitrogen 

 readily available or soluble in water are nitrate of soda' and sulphate of 

 ammonia. These sources give off the gas quite readily after being applied 

 to the soil ; especially is this true if the soil is moist and warm. For the above 

 reason it is not best to use the nitrogen from these sources till the roots are 

 in the soil ready to use it as it becomes soluble, otherwise a large per cent 

 of the gas will leak out into the ditches, streams, or lower strata of soil, or 

 will go off into the atmosphere. Nitrogen from these sources is better for 

 quick-growing crops, such as truck crops, or to use as a top or side dressing 

 when crops need extra stimulating. 



The organic sources of ammonia are cotton-seed meal, dried blood, tankage, 

 fish scrap and various others, barnyard and stable manure being a common 

 source. Cotton-seed meal is one of the best forms of organic ammonia, and 

 is most easily secured by us farmers of North Carolina on account of the 

 oil mills in our midst. It contains about 7 per cent ammonia and is finely 

 ground so as to feed the plant along through the growing season, the finer 

 particles dissolving and giving off the nitrogen first and the coarser particles 

 feeding the plant as it nears maturity. Fish scrap and dried blood are also 

 good sources for organic ammonia. As stated above, ammonia derived from 

 these sources is far better for the crops, such as cotton, corn, etc., that grow 

 through a long season, than that from nitrate of soda and sulphate of am- 

 monia. 



The value of organic ammonia as plant food is in proportion to its content 

 of nitrogen and the rapidity with which it decays and gives off the gas. Burnt 

 leather is rich in ammonia, and yet it takes several years for it to be available 

 for the plant. Thanks to our Legislature, factories are forbidden to use burnt 

 leather as a source of ammonia in this State. 



Potash, which is another essential element in plant growth, was derived 

 chiefly from hardwood ashes and decayed vegetable and animal matter till 

 about 1SG0, when the potash-salt mines of Stassfort, Germany, were discovered. 

 Since that time there has been little change in the price of potash or little 

 anxiety as to the supply. The potash we use is obtained from German kainit, 

 muriate of potash and sulphate of potash. The form of potash has little to 

 do with its value as a plant food, the same number of pounds derived from 

 kainit being worth just as much as if derived from mui'iate, the only difference 

 being the large amount of chlorine and other impurities in the kainit. Kainit 

 usually contains about 12V 2 per cent potash and muriate from 4S to 50 per cent. 

 In nearly all cases I would advise the use of muriate on account of the saving 

 in handling the extra bulk, one ton of muriate being worth as much as four 

 of kainit. For cotton, however, the kainit is better, as the common salt con- 

 tained in it has a tendency to prevent rust. 



Each of these elements has its special function in the development of the 

 plant, just as different food for cattle produces different results. Phosphoric 

 acid, for instance, is the seed-producing element; potash produces the woody 

 fiber in the plant, aids in the maturing of the fruit, makes the tuber in case 



