The Bulletin. 95 



FERTILIZERS FOR SPECIAL CROPS. 



By T. E. Browne. 



The farmers of North Carolina will have a fertilizer account for 1911 

 amounting to about .$ir),00O,O0O. Can we as a class afford to expend this 

 amount of money annually without looking into the why and wherefore of the 

 matter? It is not the purpose of this paper to discourage the use of commer- 

 cial fertilizers, or to make the impression that we are using too nuich. The 

 fact is we are not using enough. It is my intention to arouse in the minds 

 of my fellow farmers a desire to study this question from an intelligent, 

 scientific standpoint, and only expend their mouey for the elements of plant 

 food essential to the needs of the particular crop and soil for which they are 

 to use the fertilizer. 



Our forefathers knew nothing about commercial fertilizers. The virgin soil 

 contained all the elements of plant food, to a greater or less degree, that were 

 necessary to plant growth. However, by the constant cropping of these fields 

 the elements that were most necessary to plant growth were converted into 

 the farm product and sold from the land. The inevitable result followed. 

 The land became less productive, and poorer crops were harvested each year. 

 The farmers soon found that something was lacking. They used ammoniated 

 manures, and wood ashes, rich in potash, and saw marked improvement. 

 From this beginning the fertilizer business has grown to the enormity indi- 

 cated by the above figures. 



Then we use fertilizers to restore to the soil the natural elements that have 

 been removed by man. The high price of farm lands, farm labor, mules and 

 machinery have made it necessary to get larger yields from our land, and this 

 can be done by the economic use of fertilizers. Admitting, then, that the chief 

 cause of the use of fertilizers is to add plant food, we should know what ele- 

 ments we need to buy and the source from which they are derived. There are 

 about ten elements of plant food essential to the growth and maturity of all 

 plants. However, it seems that all these, except probably three, are present 

 in most soils in sufficient quantities to .meet all demands. The three elements 

 that are taken up most largely by the plants are nitrogen, phosphoric acid, and 

 potash. Therefore we are concerned only about the amount of these elements 

 contained in a ton of fertilizer. 



I might mention, in passing, the chief sources from which these elements 

 are derived. Our nitrate, or readily available nitrogen, is derived from nitrate 

 of soda and sulphate of ammonia. The chief sources of organic nitrogen are : 

 cotton-seed meal, dried blood, fish scrap, and tankage. All of these are very 

 good sources from which to obtain nitrogen, the best form in which to buy it 

 depending upon the growing period of the crop for which it is to be used. 

 Potash is derived from kainit, muriate of potash, and sulphate of potash. 

 Phosphoric acid is obtained from acid phosphate (which is phosphate rock 

 pulverized and treated with sulphuric acid), Thomas phosphate and the natu- 

 ral or untreated rock. All this is sold on a basis of the per cent of water- 

 soluble acid. 



The form of the mineral elements has little to do with their agricultural 

 value. The high-grade materials being cheaper, however, because we handle 

 less bulk in order to get a given amount of plant food. In the case of the 

 gaseous element, nitrogen, it is quite different. This is the most expensive 

 element we use, and at the same time is the mo8t easily lost. As has been 

 suggested, if we are fertilizing short-season crops, such as the truck crops, 

 the nitrate nitrogen is preferable, as the plant food begins work almost imme- 

 diately. If we are fertilizing such crops as cotton and corn we should en- 

 deavor to derive a part of the nitrogen from an organic source. As this mate- 

 rial has to decay and decompose befoi'e giving off the gas, the available nitro- 

 gen is gradually supplied the plant through the growing period, provided there 

 is sufficient moisture in the soil to carry the plant food in solution. 



It is furthermore necessai-y to know the form of the material from which 

 the nitrogen is derived, because the unscrupulous manufacturer of a mauipu- 



