174 FIELD AND GARDEN PRODUCTS 



pounds of phosphorus, and 28 pounds of potassium. If bought in 

 the form of a commercial fertilizer, nitrogen is worth 20 cents a 

 pound and the other two elements are valued at 5 cents each per 

 pound. On this basis the fertilizing value of a ton of timothy hay 

 will amount to $5.90, or $6 in round numbers. One ton of clover 

 hay contains, on an average, 40 pounds of nitrogen, 8 pounds of 

 phosphorus, and 40 pounds of potassium, which makes its fertil- 

 izing value amount to $10.40. 



According to these figures it would seem that there is less loss 

 of plant food in growing timothy than when clover is grown. How- 

 ever, such is not the case, for clover and all other leguminous plants 

 store up nitrogen in the soil. This class of plants is supplied with a 

 certain kind of bacteria, which live in the tubercles on their roots. 

 These bacteria have the power of taking free nitrogen from the air 

 and making it available as food for the growing plant. Much of the 

 nitrogen thus secured is left in the soil by the decay of the tubercles, 

 roots, stems, and fallen leaves of the legumes, to the great benefit of 

 succeeding crops. 



When a ton of clover is removed from the soil, from one-fourth 

 to three-fourths as much nitrogen is left in the roots and crowns and 

 in the fallen leaves and stems left on the ground as is removed in the 

 hay. As a greater part of this nitrogen came from the air, it is per- 

 fectly fair and proper when considering the loss of plant food in 

 growing a crop of clover to disregard or deduct it from the total 

 fertilizing value of the hay. 



When comparing the loss of fertilizing elements of clover and 

 timothy, there is a difference of about $3 a ton in favor of clover hay. 

 Just how much of this amount should be charged to the hay when 

 considering the profit from selling hay can not be stated definitely, 

 for the kind of soil, system of rotation used, and type of farming 

 play important parts in keeping up the crop-producing power of the 

 soil. 



Timothy is often said to be "hard" on the soil. This is because 

 neither timothy nor any other grass can add any plant food to the 

 soil in the manner that the legumes do, but must get all of its food 

 from the soil ; and it is therefore much more exhaustive of the avail- 

 able plant food in the soil than clover. 



Need of Suitable Rotations for Hay Lands. When crops are 

 sold from the farm year after year and no attempt is made toward 

 a systematic rotation, and especially where legumes are not grown, 

 the land in the course of time will become low in available plant 

 food and the yield will be greatly lessened. In fact, on many farms 

 the soil has been so depleted of its fertility that farming is not a pay- 

 ing proposition. It has been found that when land begins to lose 

 its crop-producing power the loss of fertility may be retarded by a 

 proper rotation of crops in which legumes, such as clover, alfalfa, 

 cowpeas, and soy beans, are grown. 



Many farmers who in the past have grown nothing but timothy 

 hay for the market are now commencing to grow clover in order to 

 help build up their land. This is why under certain conditions 



