EXPERIMENT STATION BULLETINS. 



349 



THE POTASH SITUATION DESERVES CONSIDERATION. 



Potash is leached from the soil in relatively small amounts. Analyses 

 of river, well and drainage waters taken from several parts of the humid 

 areas of the world show that this is not important in the mainte- 

 nance of soil fertility. When this element of plant-food is applied to 

 the soil it is held quite firmly until removed by growing plants. Very 

 porous sands may be exceptional however. On the other hand potash 

 that is present in hay, straw or manure is quite easily washed out when 

 exposed to the elements and may be lost so far as crop production is 

 concerned. 



Potash is contained in relatively large amounts in unleached manure, 

 one ton on the average carrying 10.5 pounds. This constitiites the chief 

 carrier of potash used on Michigan soils. Potash can be purchased on 

 the market in several carriers. 



Figure 5. — Gullying in fields makes portions of them inaccessible, unproductive and buries good 



land that lies at lower levels. 



THE LOSSES OP PHOSPHORIC ACID BY LEACHING ARE SMALL. 



The amount of phosphoric acid removed from soils by drainage water 

 is less than that of potash. Investigations conducted in England and 

 at several experiment stations in this country show that phosphoric acid 

 that is present in or added to soils is held tenaciously by them. More- 

 over it is not removed from manure or crop residues as is potash. 



Manure contains less phosphoric acid than potash, a ton carrying 

 under average conditions about 6 pounds. The chief sources of supply 

 are the commercial carriers. 



Most soils of the State respond to applications of phosphate fertilizers. 

 For further information relative to this important plant-food refer to 



