252 Practical Farming 



bacteria that live on clover roots and enable the plant to 

 get and combine the free nitrogen from the air. In many 

 of the older sections both of these causes exist. 



The practice of running land in grass for hay year after 

 year with no help from manure or fertilizers till the hay 

 crop fails, not only exhausts the plant food of the soil but 

 brings it into an acid condition. Liming will restore the 

 alkalinity of the soil, and then the use of fertiUzers carry- 

 ing phosphoric acid and potash will restore the plant food 

 needed by the clover crop. 



There has long been a notion that the continued use of 

 phosphatic rock dissolved in sulphuric acid has been 

 the cause of the acidity of soils. This acidity can hardly 

 be charged to the acid phosphate direct, for no manu- 

 facturer intentionally leaves any free acid in his product, 

 since that would prevent its drilHng freely. But that it 

 has been indirectly the cause has been well shown by 

 experiments at the Ohio Experiment Station which seemed 

 to show that the result of the continued use of acid phos- 

 phate had this effect though the crops taking up the solu- 

 ble phosphoric acid and leaving free sulphuric acid in the 

 soil, which is at once combined with the Hme in the soil, 

 and thus forms sulphate of lime and robs the soil of the 

 lime carbonate needed to maintain the alkahnity. The 

 same station found that when a liberal application of com- 

 plete fertiHzer was made, preceded by Hming the soil, a fine 

 growth of clover was had on soil where it had been faihng. 



It is evident, then, that the way to get back to successful 

 clover-growing is to restore the alkalinity of the soil 

 through the use of hme and then to supply the phosphoric 

 acid and potash that the plant especially needs. 



