366 MISCELLANEOUS FARM SUBJECTS 



some of the advantages of a sandy soil without its disadvantages, 

 in that it makes it easier to work and keep in good tilth, while it 

 retains moisture and plant food well. The size of these granules 

 varies with the soil and the length of time of exposure to the ele- 

 ments. They are larger in spring than later in the season. The 

 summer and fall rains frequently almost destroy them, and it may 

 require a winter's freezing and thawing to develop them again. It 

 is generally recognized that the soil is in better condition for plow- 

 ing after a cold winter, and this is undoubtedly due to the granular 

 character developed by freezing. A cold winter may not be sufficient 

 to restore this condition after a very wet summer. 



The complaint is often made that soils run together and bake 

 after every heavy rain. This is often true of fine-grained silty or 

 clayey soils, but not of sandy ones. It is due to the breaking up of 

 the soil granules into their individual particles by the beating of the 

 rain drops, and this produces a puddled condition of the surface 

 which, when dry, forms a hard crust through which the young plants 

 can pass or force their way only with great difficulty. The crust 

 being somewhat impervious to air, the growth of the crop may be 

 hindered by lack of aeration. The roots of growing plants require 

 oxygen, as do also the bacteria of the soil that carry on the process 

 of nitrification, producing nitrates for plant growth. A crust on the 

 surface when corn is young soon causes it to become yellow, indi- 

 cating a lack of nitrogen, probably due to the fact that nitrifying 

 bacteria are unable to carry on their work properly for want of 

 oxygen. A crust also causes a loss of moisture by increasing evapora- 

 tion, the soil having been so compacted by the rain that the soil 

 particles have been brought into close contact with each other and 

 continuous capillary connection has been established, so that the 

 water now may pass rapidly to the surface, where it is evaporated. 



Running together may be largely prevented by increasing the 

 amount of organic matter. This cements the soil particles together 

 into granules, holding them so firmly that only the hardest rains 

 break them down, and furnish the puddled condition necessary for 

 the formation of a crust. Every one has seen the effect of an old 

 strawstack or manure heap on the soil. Places where these have 

 been are always mellow when cultivated, because of the organic 

 matter contained in them. Every soil should contain enough or- 

 ganic matter so that it will not run together except with the heaviest 

 rains, and even then not so as to interfere seriously with the ordi- 

 nary physical phenomena of the soil. 



Wherever land is not level and the rainfall is greater than can 

 be absorbed, more or less washing occurs. The amount depends 

 upon the physical composition and texture of the soil, the extent 

 and slope of the surface, the presence or absence of vegetation, and 

 the character and amount of the rainfall. 



A very gravelly or sandy soil that allows the water to pass 

 downward readily is not likely to wash badly, for the reason that 

 very little water runs off by surface drainage even on a considerable 

 elope. If, however, the soil is a silty or clayey one, it will absorb 



