LOSSES IN THE FEEDING TRANSACTION 



349 



applied at the rate of ten tons per acre once in three years, 300 

 pounds of acid phosphate per acre are applied with the manure for 

 corn, and the second growth of clover is plowed under. 



Losses and Gains in Fertilizing Elements in a Dairy Farm Rotation 



The above system of stock farming tends to increase soil fertility. 



Loss and Gain of Plant-Food Elements Illustrated. In stock 

 feeding, as in dairy farming especially, considerable feeds are 

 usually purchased which help to offset the losses. Commercial 

 fertilizers are often used. Cash crops are often raised. Moreover, 

 considerable nitrogen may be leached from the soil. It is only 

 when a farmer understands clearly how the fertilizing elements 

 may be lost and the sources of gain, that he is able to direct his 

 farming towards the maintenance of fertility. As it has been 

 mentioned, the best way to determine this is to study the 

 crop yields and to note the gain or loss of nitrogen and phos- 

 phorus, particularly. 



The sources of loss and gain to the soil on the farm are illus- 

 trated in Figure 224. 



The losses by leaching concern nitrogen, particularly. Experi- 

 ments show wide differences in the amount of nitrogen lost in 

 this manner. On grass lands and on cultivated fields of low 

 fertility the annual loss per acre is slight; on cultivated fields of 

 moderate fertility the loss is about twelve to twenty pounds per 

 acre per year in regions having thirty inches of rainfall; and on 

 cultivated fields heavily manured, or in a high state of fertility, 

 the annual loss per acre may approximate forty pounds when the 

 rainfall is heavy during July, or the middle of the growing period. 

 The annual loss of nitrogen by leaching from uncropped or bare 

 fields may exceed 150 pounds per acre. 



Losses in the feeding transaction include the elements retained 



