FARMIiKS' INSTITUTES. 245 



IMPROVEMENT BY ADDING HUMUS. 



I have spoken of tillaj^^e as a means of making potash and p^liosphoric 

 acid sokible. Tlie solubility of phosphoric acid also seems to be closely 

 related to the amount of humus present in the soil. Professor Snyder of 

 the Minnesota Experiment Station has shown that the soils rich in humus 

 contain three times as much soluble phosphoric acid as those in which the 

 percentage of humus is low. If we suspect that our soils are deficient in 

 phosphoric acid it might be well to apply a good coating of barnyard ma- 

 nure and improve our method of tillage before buying bone meal. If 

 good tillage and plenty of humus will not secure good crops it is then 

 time to think of purchasing commercial fertilizers. Improvement of soils 

 does not necessarily mean the addition of fertilizers as too many people 

 are prone to believe is the case. 



The restoration of humus to soils is the cheapest and best method of 

 replenishing a diminished nitrogen supply. This may be accomplished by 

 growing leguminous plants, the roots of which are allowed to decay in the 

 soil, forming humus and adding nitrogen directly, since all the nitrogen 

 found in them was obtained from the air. If the tops are removed how- 

 ever, it must be borne in mind that these plants remove large quantities of 

 potash and phosphoric acid, and consequently the supply of these two 

 elements may be rapidly depleted and even reduced to the danger point 

 while the supply of nitrogen is being increased. They have one advantage 

 however, in their deep root system which enables them to obtain these ele- 

 ments from depths in the soil below the feeding field of other plants. Thev 

 must not, however, be considered a universal remedy for worn out soils. 

 If they are used as a cover crop and the tops plowed under, they are then 

 to add nitrogen in large quantities, while no potash or phosphoric acid 

 would be removed. 



Barnyard manure is a cheap and often neglected source of humus. 

 It produces the best effect if thoroughly incorporated with the soil when 

 it is wet and well rotted, but since by ordinary methods of handling, from 

 one-half to two-thirds of it is lost by the time it becomes well rotted, farm- 

 ers greatly in need of humus may haul out such manure as soon as it is 

 formed and let it rot in the soil that needs it. There will be no bad results 

 from this method where there is plenty of rainfall, but where there is a 

 drouth during a portion of almost every summer, sometimes the presence 

 of unrotted manure in the soil may increase the efifects of the drouth. I 

 have known this to occur, but the increased yields obtained for more than 

 ten years after the application of the manure, much more than compensated 

 for the loss incurred the first season. 



