392 MISCELLANEOUS FARM SUBJECTS 



genous bodies. The leguminous plants are the most effective as 

 green manure and the manure from a grain-fed horse is more ef- 

 fective than from a horse fed principally hay or on pasture. The 

 protein bodies are as a rule very complex and break down through 

 oxidation, fermentation, and the action of enzymes or bacteria into 

 bodies many of which are now known to be beneficial or detrimental 

 to plants. The same original substance may break down into bene- 

 ficial or detrimental substances, according to the agencies acting on 

 it and the conditions under which they act. Fresh pea vines and 

 pea-vine hay may, and usually do, give very different results when 

 applied to any particular soil. Ground wheat seed and germinating 

 wheat seed have very different effects on the soil. So it is evidently 

 not the nitrogen, but the compound, which determines the action on 

 the soil. 



It is generally believed that the beneficial effect of nitrogenous 

 fertilizers is due to nitrification, through bacterial action, with the 

 ultimate formation of nitrates, and this is undoubtedly important, 

 not so much because of the nitrates formed, but because decomposi- 

 tion proceeding in that way is generally more beneficial than if it 

 proceeds in other ways when other less beneficial intermediate prod- 

 ucts may be formed. 



Carriers of Nitrogen. The substances commonly used as car- 

 riers of nitrogen are nitrate of soda, sulphate of ammonia, cotton- 

 seed meal, dried blood, tankage, fish scrap, guano, and castor pomace. 

 Other nitrogenous substances, like horn, hair, feathers, and wool 

 waste, are prohibited by the laws of many States from being incor- 

 porated into commercial fertilizers, as they are not considered good 

 substances for fertilizer use, although they are highly nitrogenous. 



The substances commonly used as carriers of potassium are kai- 

 nit, muriate of potash, sulphate of potash, and carbonate of potash. 

 There are other potash salts, as, for example, iodide of potash and 

 chlorate of potash, which are harmful and could not be used in 

 fertilizers even if they could be obtained cheaply enough. 



It is the experience of farmers and investigators generally that 

 these different carriers of phosphorus, of nitrogen, and of potash act 

 differently on different soils and in different seasons and with dif- 

 ferent crops that is, that raw rock phosphate, ground bones, bone- 

 black, acid phosphate, floats, and slag are different substances which 

 may act differently on different soils with different crops and with 

 different seasons. Likewise that nitrate of soda, sulphate of am- 

 monia, cotton-seed meal, dried blood, fish scrap, and guano are dif- 

 ferent substances in an agricultural as well as in a commercial sense, 

 and this in addition to their differences in nitrogen content. 



Most tobacco growers and many truck and fruit growers recog- 

 nize a difference in the agricultural value of kainit, muriate, sul- 

 phate, and carbonate of potash as influencing the quality if not the 

 yield of their crops. It is true that no definite law has ever been 

 worked out even for a particular field, but this is probably due in 

 large measure to a lack of knowledge of how these substances act and 

 the influences which control their action on the soil. 



