EFFECT OP CONTINUOUS CROPPING. 135 



as feeding the plants is concerned their worth rests upon the 

 elements of fertility they contain. 



It %viH, therefore, be seen that barn-yard manure has a high 

 value as a fertilizer. It is perhaps the most important for soil 

 improvement. The reason for this is that It supplies nitrogen, 

 phosphorus, and potash and the decaying organic matter needed. 

 In feeding oats, com, wheat or other crops to animals, it is well 

 to know that about threer quarters of the phosphorus and nitrogen 

 and practically all of the potash go through the body and are re- 

 turned In the solid and liquid manure. It is evident that the value 

 of richness of the manure depends largely on the crops or part 

 of the crops fed to the animals. That which originates froni the 

 use of concentrated feeding stuffs usually has a high value. That 

 which comes from the use of straw or other coarse forage has a 

 lower value. Leguminous crops are rich in nitrogen and phos- 

 phorus. Three tons of white clover will contain 8 pounds n;iore 

 phosphoric acid and 17 pounds more nitrogen than a 100 bushel 

 corn crop, i. e., 31 pounds phosphoric acid and 165 pounds nitro- 

 gen. Any system of farming where grain is sold and only stalks 

 and straw retained for feed produces manure weak in both nitro- 

 gen and phosphorus. These elements are divided in the corn 

 plant on the 100-bushel basis, about as follows: 



100 lbs. nitrogen in grain and 48 lbs. in the stalk. 

 17 lbs. phosphorus in grain and 6 lbs. in the stalk. 

 19 lbs. potassium in grain and 52 lbs. in the stalk. 



In other words, two-thirds of the nitrogen, three-fourths of the 

 phosphdrus and one-fourth of the potassium are in the grain or 

 seed and one-third of the nitrogen, one-fourth of the phosphorus 

 and three-fourths of the potassium are in the stalk or straw. ' In 

 siloing the com plant the full value of the fertilizer, in both stalk 

 and grain, is obtained in the manure. 



The value of manure depends very largely on the way in which 

 it is handled. Over half the value is in the liquid portion. 



Experiments were conducted at the Ohio Experiment Station 

 With two lots of steers for six months to ascertain the loss 

 through seepage. An earth floor was used for one lot and a 

 cement floor for the other lot. Manure was weighed and analyzed 

 at the beginning and end of the experiments and it was found that 

 that produced on the earth floor had lost enough fertilizer through 



