UNITED STATES DEPARTMENT OF AGRICULTURE 



BULLETIN No. 512 



Contribution from the Office of Public Roads and 

 Rural Engineering 

 LOGAN WALLER PAGE, Director Si^^^^U 



Washington, D. C. 



PROFESSIONAL PAPER 



April 5, 1917 



PREVENTION OF THE EROSION OF FARM LANDS 

 BY TERRACING. 



By C. E. Ram SEE, Drainage Engineer. 



CONTENTS. 



Introduction 1 



Jorms of erosion 2 



Methods of preventing erosion 3 



Deep tillage and application of humus 3 



Use of cover crops 4 



Practice of level c^ulture 4 



Pasturing and foresting 4 



Underdraining 5 



Use of hillside ditches 5 



Terracing 5 



Definition and classification of terraces 6 



The bench terrace 7 



The level-ridge terrace 10 



The narrow-base form 10 



The broad-base form 12 



General discussion 18 



Terracing — Continued. 



The graded-ridge terrace 21 



The narrow-tiase form 21 



The broad-base form 22 



Terraces with uniform grade 24 



Terraces with variable grade 27 



Outlets 28 



General discussion 29 



Comparison of terrace types 30 



Laying off a terrace system 32 



Construction of terraces 35 



Maintenance and cultivation of terraces 37 



Reclamation of gulUed lands 38 



Summary 38 



INTRODUCTION. 



The existence of vast areas of so-called worn-out hill lands 

 throughout the United States may be attributed chiefly to soil erosion, 

 due to the natural agencies of wind, frost, and rain. In most lo- 

 calities wind and frost, owing to their comparatively slow processes, 

 play but a minor part in the depletion of the soil and the ultimate 

 destruction of good farm lands. It is the failure of the soil to 

 absorb the rain water which falls upon it that presents by far the 

 most serious aspect of the problem. It is estimated ^ that the Poto- 

 mac Kiver each year carries off in solution about 400 pounds of solid 



^ Bulletin 17, North Carolina Geological and Economic Survey, p. 21. 



Note. — This bulletin treats of terracing as a means of preventing erosion of hillside 

 land. It describes the different types of terraces and points out the applicability of 

 each to the various kinds of soil and topography. It discusses the principles of terrace 

 design. While the investigations upon which the recommendations are based were made 

 in the Southern States, the information is applicable generally to any State in the 

 tiumid section. 



71775°— Bull. 512—17 1 



