SOIL MANAGEMENT 17 



are accomplishing this result by making use of the knowledge 

 which they have acquired through years of experience and a 

 study of the character of their land, its adaptability to crops, 

 and methods of management and manuring. Other farmers have 

 accomplished the same results in a much shorter period of time 

 by acquiring a definite knowledge of the fundamental principles 

 and making use of the experience of others. 



Grain and livestock farming. — In the system of grain farming 

 that has been practiced over large areas in this country for long 

 periods of time, and is still practiced, the livestock is often lim- 

 ited to the number needed for labor, the grain is sold and only 

 the straw and stalks returned to the land. "Where a part or all 

 of the grain produced is sold from the farm it becomes a neces- 

 sity sooner or later to supply plant food materials from outside 

 sources and to make provision for keeping up the supply of 

 organic matter in the soil by jDlowing down sod and by the 

 growing of green manuring crops to be plowed down. 



In livestock farming the same results are accomplished by 

 feeding the crops grown on the farm and saving the manure and 

 returning it to the land. If in addition to feeding all of the crops 

 grown on the farm, concentrated feeds are purchased and fed, 

 the loss of soil fertility may be reduced to a minimmii, or there 

 may result an actual gain in fertility. 



This system of farming is even more effective if some of the 

 produce that is low in fertilizing constituents is exchanged for 

 more concentrated feeding stuffs. For instance, the exchange of 

 a ton of corn for a ton of wheat bran Avill result in a gain of 

 twenty-one pounds of nitrogen, forty-six pounds of phosphoric 

 acid, and twenty-four pounds of potash. AVith an exchange of 

 milk or jiotatoes for concentrated feeds the gain is even greater. 



Stable manures. — The manure produced by farm animals 

 constitutes one of the most valuable assets that the farmer has 

 at his conmiand for the i^urpose of keeping up the fertility of 

 his land. The total annual production of manure, both solid and 

 liquid, for each thousand pounds of live weight is about nine 

 tons for the horse, thirteen tons for the cow, fifteen tons for 

 swine, and about five tons each for sheep and poultry. The wide 

 variation in the amount produced by the different classes of 

 animals is due largely to the difference in the amount of water, 

 horse, sheep and poultry manure being comparatively dry while 

 cows and SA\^ne produce a wet manure. 



Handling manure. — Under the conditions that prevail on most 

 farms much of the value of the manure is lost bv failure to 



