SOILS AND FERTILIZERS 409 



ferent times. The manure from a well fed animal is much more 

 valuable than that from a poorly fed one. The droppings of a half 

 starved animal possess little value as a fertilizer. It is hardly prof- 

 itable to use, but when the animal has been well fed, on a rich diet 

 like cotton-seed meal or wheat bran, it has been proven that the 

 plant food locked up in the animal manure is more valuable from 

 a money standpoint than was the food itself when purchased in the 

 market. When fed to stock, cotton-seed meal is known to produce 

 a manure of excellent quality. These seeds are now used in im- 

 mense quantities as a source of nitrogen in the manufacture of com- 

 mercial fertilizer, but it would be much better for the farmer who 

 grows his seed to exchange them for an equal weight of hulls and 

 meal. The manufacturer is generally willing to make this agree- 

 ment, and finds his profit in the oil collected from pressing the seed. 

 Upon the other hand, the oil in the seed has no fertilizing value, 

 and, in this way, the farmer would gain more real plant food by 

 making the exchange. Then by purchasing phosphoric acid and 

 potash, and mixing them with the meal, he will have another com- 

 plete fertilizer to supplement his store of barnyard manure. 



Barnyard manure is one of the most efficient means at the dis- 

 posal of the farmer to permanently improve his soil. Probably no 

 other fertilizer possesses to so great a degree the power of restoring 

 worn soils to productiveness and giving them lasting fertility. It 

 accomplishes this result, however, not so much by the actual fer- 

 tilizing constituents which it supplies as by improving the physical 

 properties of the soil, increasing the amount of humus, which is 

 generally deficient in worn soils, improving its texture, and increas- 

 ing its water-absorbing and water-holding power. Experiments 

 have shown that the influence of manure may be perceptible twenty 

 years after application. Observations at Rothamsted, England, dur- 

 ing forty years on barley unmanured, manured continuously, and 

 manured during the first twenty years only showed that there was 

 gradual exhaustion and reduction of produce without manure, and 

 gradual accumulation and increase of produce with the annual appli- 

 cation of farmyard manure. But when the application was stopped, 

 although the effect of the residue from the previous applications was 

 very marked, it somewhat rapidly diminished, notwithstanding that 

 calculation showed an enormous accumulation of nitrogen as well 

 as other constituents. 



Feeding-stuffs contain plant food. After they are used by the 

 animal, most of the plant food is excreted by the animal in the 

 solid and liquid excrement. A small portion is retained by growing 

 animals, and a portion is used by cows in the elaboration of their 

 milk, but the largest part passes off. The plant food in the excre- 

 ment is equally as valuable as that in the food, pound for pound. 

 The farmer who feeds cottonseed meal and wastes the manure gets 

 only the feeding value of his feed. One who buys cottonseed meal 

 for use as a fertilizer gets only its fertilizing value. But one who 

 feeds the meal and saves the manure secures both the feeding value 

 and a portion of the fertilizing value of the feed. How much of 



