366 CROP GROWING AND CROP FEEDING 



15. While experiments with fertilizers will show that the best results 

 are obtained from a complete fertilizer in which there is a due proportion of 

 nitrogen, phosphoric acid and potash, it by no means follows that it is to the 

 farmer's interest to use the complete fertilizers when by a proper rotation of 

 crops and the use of legumes he can get without cost and often at an actual 

 profit, the nitrogen which makes the greater part of the cost of the complete 

 fertilizer. A long experience in the cultivation of the soil enables us to say, 

 without fear of successful contradiction, that for our ordinary farm crops 

 such as cotton, wheat, corn, etc., there is never any need for the purchase of 

 a complete fertilizer, if the proper rotation of crops is followed, legumes 

 grown and used as forage and manure saved with care and applied in the 

 best place. 



16. On crops of extra value, such as those of the market gardener, it 

 pays to use the complete fertilizers in a lavish and apparently wasteful man- 

 ner where the early crops thus grown are followed by legumes for feeding and 

 the accumulation of humus. The tobacco grower, too, finds that it usually 

 pays to use a complete fertilizer, though we a"re not sure that even here the use 

 of the legumes may not give as good results, though further experiments 

 are needed to determine this. 



17. Where it is necessary to use artificial nitrogen the most readily avail- 

 able form is nitrate of soda. But this should never be used on plants in a 

 dormant state, since it is very readily leached from the soil if not at once 

 used by plants. The nitrate is valuable to start off plants in the early season, 

 but should always be accompanied by some form of organic nitrogen to keep 

 up the effect after the nitrate has been used, and to gradually produce nitrates 

 in the soil, since it has been ascertained that crops take nitrogen only after 

 it has been reduced to a nitrate in the soil. The best forms of organic nitro- 

 gen are found in cotton seed meal, pulverized fish scrap, dried blood and tank- 

 age, and the poorest of all is pulverized leather scraps. 



18. Pay no attention to the man who would persuade you that phosphoric 

 acid in a soluble form is better from one source than another. Phosphoric 

 acid in animal bone, in phosphatic rock and in furnace slag is one and the 

 same thing, and the only thing you need bother about is its solubility. Phos- 

 phate rock dissolved in sulphuric acid is largely soluble. Phosphoric acid in 

 raw bones is all insoluble, though from the nature of the material it may 

 become soluble more quickly than that in untreated rock. A superphosphate 

 made from animal bones by dissolving them in sulphuric acid is better than 

 that from the rock only because it has a larger per centage of phosphoric acid, 

 but it, of course, costs more for this reason. One per cent, of the one is fully 

 as good as one per cent, of the other. Phosphoric acid in Thomas slag is 



