EXPERIMENT STATION BULLETINS. 343 



LOSS OF TLANT FOOD ELEMENTS FROM SOILS. 



Popular Bulletin No. 290 



BY M. M. MCCOOL, C. E. MILLAR, G. M. GRANTHAM, SOIL SECTION 



Virgin soils in humid regions become less fertile with age. In various 

 sections of the United States there are large areas of rather heavy lands 

 which were in a very low state of fertility when first settled by the white 

 man. These areas were once very productive but due to the various 

 climatic factors operating through long periods of time they became de- 

 pleted. It is evident therefore that there are certain natural agencies 

 which tend to impoverish the soil. When soil is brought under cultiva- 

 tion usually these natural agencies are stimulated to a certain extent 

 and new ones are also added. The most important of these are leaching, 

 erosion and the removal by crops. 



THE LIME PROBLEM IS GENERAL. 



The amount of lime removed by leaching is greater than the amount 

 of other substances lost in a similar manner. Tests conducted by farm- 

 ers, county agents and members of the Soils Section show clearly that 

 many of our lands have reached the stage where liming is advisable for 

 satisfactory crop production, especially if one desires to grow the 

 clovers, alfalfa and vetch. There are reasons for this condition. Lime 

 is constantly removed from soils by leaching or washing by rain water 

 that falls on them and by the crops that are harvested. The loss of 

 lime from the soil is exemplified by the conditions that exist in many 

 places in Michigan. When the better classes of our soils were left by 

 the glacier they contained about the same amount of carbonate of lime 

 from the surface downward. Of course the different kinds of soil varied 

 from one to the other. Our soil surveys show that carbonates do not 

 exist even in the fine textured soils over much of the State above thirty- 

 six inches, although in some types it lies within eighteen inches of the 

 surface, whereas in sandy soils it has been removed to depths ranging 

 from four to ten or more feet. The marl beds bear witness of this re- 

 moval from the upland soils and owe their existence to it. This means 

 that sooner or later all soils will become deficient in this substance and 

 must receive it in some form if they are to continue to be productive. 

 Our investigations also show that not all of our soils are deficient in 

 lime or respond to its application. It may be cited for example that the 

 finer textured soils of the Old Lake Bed of eastern Michigan, the Thumb 

 area and the Saginaw Basin are not in need of it. Aside from these 

 and portions of the soils in Alpena, Presque Isle, Cheboygan, Emmet, 

 Charlevoix, Antrim, Otsego, Grand Traverse and Leelanaw counties, the 

 majority of the soils in the southern Peninsula are deficient in this ele- 

 ment. 



When it is considered that lime is necessary for soil productivity and 

 that it is lost by leaching or washing and by removal of crops from the 

 land the conclusion is logical that the use of it in some form is one of 

 the necessary practices involved in permament systems of agriculture. 



