greater resistance to rate of run-off and therefore to erosion. 

 Deep preparatory tillage subsoiling is especially favorable 

 to increased absorption and retention of rains and melting 

 snow on soils having hardpanlike subsoil (but not with sticky 

 clay subsoils such as run together and become again impervi- 

 ous with the first saturating rains). 



Second; contour plowing at right angle to the slope is 

 an important part of the best farm practice. Because of the 

 custom, particularly in the Middle Western States, of laying 

 out counties, townships, highways, sections, and fractions of 

 sections on rectangular lines, there has developed the custom 

 of fencing fields on similar rectangular lines and of plowing 

 parallel to the fencing. (It is of interest to note that generally 

 in Europe the boundaries of properties and fields follow con- 

 tours.) This causes many furrows to extend down slope, 

 thereby making them channels which hasten run-off. The 

 wise practice is to plow with the contour, rather than up and 

 down the slope, so that furrows are at all places at right angle 

 to the direction of flow of surface water and thereby serve as 

 obstacles to run-off. This promotes retardation and infiltra- 

 tion and causes sheets of water to drop any soil they are 

 washing off at the points where they strike ridges formed by 

 the furrows. 



Third; where cultivation is on moderately sloping land, 

 terracing is helpful. We do not have in mind the laborious 

 terracing of the walled type found in countries where fertile 

 land is scarce and every square foot, even on mountain sides, 

 must be cultivated, as in the vine country along the Rhine; 

 what we have in mind is simpler but nevertheless helpful. 

 There are various kinds of terracing (Mangum, now most 

 favored, Nichol's, Duley's, and Onley's) between which it is 

 not practicable to distinguish here, but the common charac- 

 teristic is the creation by grading up of approximately parallel 

 ridgelike strips of soil, generally variable as to grade, but of a 

 grade considerably less than that of the slope across which 

 the terraces are constructed. The greatest change in level 

 is concentrated in the shoulders, which may be strip-planted. 

 The water channel above the terrace ridge must not have a 

 grade steep enough to cause excessive scouring. In humid 



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