8 SOILS OF THE EASTERN UNITED STATES. 



Thus the range in altitude within the limits covered by the two types 

 gives rise to a wide climatic variation, limiting the characteristic 

 crops which may be grown in the different zones of this elevation. 

 This climatic environment, due to altitude, will be discussed more 

 fully in the consideration of fruit crops suited to production upon 

 the Porters black loam. 



IMPROVEMENT IN SOIL, EFFICIENCY. 



The chief improvement in the effective cultivation of both the 

 Porters loam and the Porters black loam should consist in the adop- 

 tion of methods whereby excessive erosion could be held in check. The 

 most effective methods for the prevention of soil erosion in mountain- 

 ous sections consist in the terracing of the cultivated fields, whereby 

 narrow, almost horizontal strips are left to grow up to grass, separat- 

 ing the tilled areas from each other in concentric bands and permit- 

 ting surface waters to flow directly down hill only for short distances 

 until they are checked against the grass-covered terraces. The sys- 

 tem of terracing must necessarily be combined with that of contour 

 farming. This method consists of laying out the rows of all inter- 

 tilled crops in a nearly horizontal alignment around the slopes of 

 the hills, so that the water furrows between the rows have only a 

 gentle gradation and no great velocity can be gained by the rain 

 water flowing across the surface. Upon the more gentle slopes this 

 method of combined terracing and contour farming is usually ade- 

 quate to check the gullying and the more serious erosion of the field. 

 It is also desirable in the tillage of the land to use cover crops which 

 will occupy the soil during the winter and spring months to form a 

 mat of surface vegetation and to assist, through the binding action 

 of the roots, in retaining the soils in place. 



Throughout the area occupied by the Porters loam and Porters 

 black loam rye and winter wheat are possibly the best crops for this 

 purpose. Upon the Porters black loam, owing to the large amount of 

 organic matter present in the surface soil, some little difficulty is 

 experienced in the production of these two crops for grain through 

 the " heaving out " of the crops by freezing and thawing during the 

 earlier spring months. This, however, should not interfere with the 

 use of the crops to prevent erosion, even though the grain yield is 

 somewhat reduced. In the case of the Porters loam it would also 

 be particularly desirable to incorporate additional amounts of 

 organic matter in the surface soil and gradually to increase the depth 

 of plowing, in order that a deeper absorbing reservoir might be 

 formed for the rain water, thus preventing the bodily slipping away 

 of the surface soil when it is in a saturated condition and the under- 

 lying clay is thoroughly lubricated by the excess of moisture. 



