xt7n5t3g0949 https://exploreuk.uky.edu/dips/xt7n5t3g0949/data/mets.xml   Kentucky Agricultural Experiment Station. 1937 journals kaes_circulars_003_304 English Lexington : The Service, 1913-1958. Contact the Special Collections Research Center for information regarding rights and use of this collection. Kentucky Agricultural Experiment Station Circular (Kentucky Agricultural Experiment Station) n. 304 text Circular (Kentucky Agricultural Experiment Station) n. 304 1937 2014 true xt7n5t3g0949 section xt7n5t3g0949 }
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` UNIVERSITY OF KENTUCKY
  COLLEGE OF AGRICULTURE
  Extension Division
‘ THOMAS P. COOPER, Dean and Director
I 1....
I
I CIRCULAR NO. 304
I
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I SOIL EROSION AND ITS CONTROL
I
 
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Lexington, Kentucky
' July, 1937
I
_ 4 Published in connection with the agricultural extension work carried on by co-opera-
tion of the College of Agriculture, University of Kentucky, with the U. S. Department of
Agriculture, and distributed in furtherance of the work provided for in the Act of Con-
T. gress of May 8, 1914.

   V
CONTENTS
Pa;
l’AR’r 1. Cui;rex,ui l’i<-xc·iicrs ..... , .....,...,.....,,........,.. . ..... __ ;
Statistics on erosion .....................,....i.....,...,......,.4..4. ._ g
Methods of control .......,.......,...................,.....,.4.4......, j
By vegetation ......,.........................................,.44.,, zu .
By contour cultivation and strip cropping ...........r. . .......,...   j
l’.»xicr 2. '1`i;iu<.»yc;ix<: ...........,............,.............4.,...4.....,,_ t
Terraces as a factor in controlling erosion .............,.4.,...4..,....4,_ ~
\Vhere to construct terraces ........................ , 4............,..   ~.
Types of terraces ,..... . ..........t.. , .......................4...,,..,,_ li B
Dimensions for hroad—hase terraces ............,...,....,.4.4...,..,...._ l· T
Terrace grades ....................................t,........,......._,_ l_
Spacing for terraces ......4..,.. . ...,..................t.............   l
Terrace outlets ......,..............................,.............r...., l
Outlets with vegetative cover ..............................,.V.....,,_ l.
Dimensions ol vegetation covered outlet channels ..................V.. _ l' Tllc
Natural drains as outlets ......,.....,...........................t..__ |` is Wale]
Constructed outlet channels .................,..,......4...........,. , l·
lise ol dams in outlet channels .....,...........,.4.......... i . ..r_ i` less TOT
Outlets protected hy hoth dams and tegetation ......,.4...,t,.........   require
How to plan a system of terraces ............,.......,.....4....,.4 , ...4 li [all U)
l’reliminary survey ................,....,.....,..,............. . .,., if
Slope ol` the land ..........4...,..,.....,.....,...............r,.,.,_ if SUN Ol
To stake out a systetn of terraces ..,.r..,.....r....,...4.....4.....,,.., ,1* lgsg lm
Surveyin· ec ui xment ...........................,..t..,..........4.r, L , I _
How Ito Tiegiln I ....................,................,..,,.....4....4.. !~ ‘ll)l)C‘u
How to locate the terrace line .....................,,..t4...,........, 2 1`CElCh€(
Spacing the terraces .· ...............,..........,...t.........,...... , it remove
Gracie in the terrace line ........................,...,....t4t4.......,  
Resetting stakes on the terrace line ..................4t....,...,...., i T the HCC
COIISIYUCITOII of lCl'I`1lC€S , ..............................,.....,......... , J" nature
Effect of change of slope on grade of terrace channel ..4..,.....,..4.. .   ·[ S .]
Terracing machinery .....................,..........4.....,.4....... 2· l' Ol
Procedure in construction .............,...............,..4.......... ,   but cO1
Construction with horse-drawn or tractor-drawn graders ...........,.. . Z1} ~ which
Checking the terrace grade ......,..........................,.4...,.. 2*
Making fills in terrace ridges .....,.....,...........,...........4.... . PI: CHECK (
Maintenance of terraces and outlets .......,,.....,..t..,.......,,..     €l·0d€d
Plowing a terraced field ............. , ..............,,.........,..., . i.i
Planting a terraced field .............,...........,..,................ Fl
l’.ucr 3. Ctnirytxtz Asn lis Ttu-ixiurxi ....,......,.........4.....4t.... .  
Causes of gullying .....,..r...,....,............,.,....,,,......4... . lil Acc
Damage from gullying , .....,........,...............,...4........,.   it is C`
Methods for control of gullying ...........r.........,......4,....,..... . lil `
Structures for checking head erosion .......,,...........r..,..t...... i IV; slams
Dams for controlling erosion in the gully channel ..,.r.r.,..........., . if Culmy;
Specifications for single—post hrush dam ....4...........,...4..,...... . l; I l
Specifications for double-post hrush dam .............,..4.4......4... . ii ml pf
Specifications for wire dam. ..,...........,,.....,......,..i.....,... . ifi ?ll)L1]‘t
Sod bag dam ........... . .......,..........,........,.....,..i,... ..   ages al
Loose stone dam ..,.......... , ........,..,...........i....,....i. .. ·
Log dam ............................,...i,........4......4..i4.....i if of tilt?
General specifications for check dams ........,...4.....i.....,i...... . i' arc av;
Spacing check dams ...............,,...............,.,.......i..... . i` _
Size ol` the spillway notch .................................i..........   , Tr
Sloping gully banks .....................,............4.....,........ . li service  
Permanent check dams ..,.....,...........,,.......................... . il out the
Specihcations for a rubble masonry dam ............,.....,,,....4.. M     Fast
Specifications lor Ll concrete clam ...,,.i..,....i............,,......» · li Robzvgsl?
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V

 { Circular N0. 304
q, _ (T0 replace N0. 129)
· Q Soil Erosion and Its Control*
-   By GEORGE ROBERTS, EARL G. WELCH and J. B. KELLEY
i t *"""”
i i Part 1. Cultural Practices
i if The greatest single cause of loss of fertility from Kentucky soils
- l` is water erosion. Practically the whole area of the State is more or
lll less rolling, much of it being too steep for cropping systems that
  require frequent plowing. \tVhere there is enough slope for the rain-
  [all to run ofl, washing occurs unless the soil is protected by some
  Q; sort of vegetation. The earlier stages of erosion are chiefly more or
.,   less uniform sheet washing, which often is unheeded until gullies
··   appear that interfere with cultivation. Usually, when this stage is
  reached, much if not all of the original plow layer of soil has been
--   removed. The surface 8 to l0 inches of virgin soil contains most of
    the accumulated organic matter (humus) from plant growth which
.. J" nature returned to the soil thru the ages before man began to till
"   it. Soil organic matter not only contains the nitrogen of the soil,
  but contains the other elements necessary for plant growth in forms
··   ` ‘ which become available as the organic matter is decomposed. The
 QQ, effect of its loss is very evident in the lower productivity of the `
    eroded areas of slopes, as compared with non-eroded areas.
_ _, ,.l
    SOME STATISTICS ON EROSION
    .»\ccording to a report of the National Resources Board (1934)
··   it is estimated that 35,000,000 acres of farm land in the United
*4    States have been damaged by erosion beyond reclamation for agri-
    cultural purposes; that 1%,000,000 acres have had most of the origi-
iii   nal plow layer of soil removed; and that on 100,000,000 acres more
    H part of the plow layer has been removed. The total of these acre-
  it ages amounts to nearly 30 percent of the total crop and pasture land
  V of the United States. \tVhile no accurate estimates for lientucky
    are available, it is reasonable to believe that considering the topo-
‘‘``     This circular is intended for the use of both farmers and those rendering technical
·--- ljt Service to farmers, The amount or it that can be put into practice by the farmer with-
    ¥;liw*;;€t:;i;t1in;%of in engineer will of course vary with his training·and experiencei
{ Q gt · tn two multi., .,X$“?·p1§p§?.B?E.§’$‘i§§ '.,'1‘h§f §Z§E1lZ§fai$YZt ih?1E..”El°$§`.S$`i»TSZZISSE “
‘ ‘ i Roberts; Parts 2 and 3, by Earl G. Welch and J. B. Kelley, jointly. ~
  `
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 t
4 Kentuc/cy Extension Circular No. 304  
graphy and the rainfall, erosion has occurred in the State equal ml ·
the average for the United States.   ycgg,
H. H. Bennett, chief of the Soil Conservation Service of tlrtl vides a t
United States, gives the estimate* that 126 billion pounds of plautj serious e
food materials are annually removed from the crop and pasture out a ‘
land of the United States by erosion, and that tl1e value of the 11i— checking
trogen, phosphorus and potassium removed, at the lowest prices at porous a
which they could be purchased in fertilizer materials (1928), wrt the run-
two billion dollars. lf Kentucky had the average rate of erosioiij upitis r
the State’s share of this loss was $34,000,000 Plant food losses fromj of water
erosion are estimated, in this same publication, to be more tlizml together
twenty times as great as by crop removal. Mr. Bennett quotes tml Tlw
eminent geologist as saying that he would be unwilling to name sl the force
mean rate of soil formation greater than 1 foot in 10,000 yeaivj is doubl
Man is allowing the soil to wash away, in many cases, at. the rate all (0) UIC i—
a foot in less than a lifetime. H. A. \t\’allace, Secretary of Agricul-j ll1lYf)’il\\
ture, states in the United States Department of Agriculture Yettij sixty-lou
book for 1933 (page 60) that "No nation in history has permittull A [{0
its farm lands to waste away so rapidly as has the United Statcsj UIC 5Oll
()ur agriculture cannot withstand such losses indefinitely/’   Cause gc
There were in Kentucky in 1933 about 3.4-00.000 acres of lantllw mus? nl
in corn, tobacco, and miscellaneous crops that leave the soil bait  Cmsmlll
when harvested. The combined acreage of winter grains harvestctljj be lml l
in 1934 was 330,000, leaving more than 3,000.000 acres unprotectc·tl_. Smls élm
thru the winter, unless winter grain and other crops were sown let   g The
cover and not harvested. Observation leads to the conclusion tltztt  T Uxllwllll
at very large part of this land was unprotected by a cover crop. lm  Slope of
the removal of one inch of surface soil from an acre of average Kerr   "i*l`l"l'*
tucky soil, approximately 100 to 150 pounds of plmspliortis, Still  “'f>Ul_[ appro-
) percent
approved
lent cou- `
Ltures in l
ntract is y
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1
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 Al
S K""ll"'k$` Exlwzsion CIiI`(.'lI[(H` N0. 30-1  ’
on exactly the contour and each end of it were stopped, water would   [he lm
stzmd in it to the same depth the lull length ol the furrow. Contour Q were (
cultivation is especially helpful with row crops like com amd Lobnu l_ In
lg`]   _ "I- · ·“‘.` ' " I. ·: ·~ In Y `lfli l    
'¥·,_,_,»,_   I » i. li" ‘  /_,,_. vl.—4 J ,.;.   . with 1
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_ it ol lmd
Fig. 1. Sweet clover starting on badly gullied land. { L
; should
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Fig. 2. The same as Fig. 1, but later in the season. Plodu
H\'Ql`llgQ
(`O. ll   HOL UIICOHIHIOII Lo SCC COI`!] CLllLlVZll€(l Lh€ lllsl Li1llC \\'llll llOl`lZ()Ill
lllC Sl()l)C. Lllld COV€1‘ CI”()l)S S€€(l€(l [l1€ SZIIHE WHY. EXl)€l`ill1€IllS lll · flop 1`OI
. Alzibzunzfl showed that where cotton rows were run with the slopr llzldlr dl
-—-— lll
' Alabama Experiment Station Bulletin 245. Sheet erosion studies on Cecil clay. 19Jl l neil

   Soil Erosion and [ls Control 9
ultl   the loss of soil by erosion was about twice as great as where the rows
'>l1l`   were on the Contour.
>at:—   [11 strip cropping, the hillside is laid off in strips approximately
f   ,,1] the contour, and strips of crops like hay or grain are alternated
iii S  with intertilled crops like corn and tobacco, so that run-off from
Fal  i [twin is checked. A regular rotation may be used on tl1e strips, just
   i as a rotation is used in {ields on more level ground, provided inter-
    lillgtl crops and crops forming continuous cover are alternated. It
,_·  · i5t)ftCl1 helpful to leave sod strips between the strips in strip crop-
    ping, It may also be helpful to leave sod strips at intervals on the
  _Q  (—ontot11· on steep la11d where a long slope is to be broken for row
 5;  i trops.
{5 i.  Part 2. Terracing
    TERRACES AS A FACTOR IN CONTROLLING EROSION
   S .-\s stated in Part 1 of this circular, terracing is IlCC(lC(l under
fi ·  many conditions to supplement cropping practices i11 the control
Q   of erosion. .-\ terrace is a ridge of earth thrown up across the slope
` ,- of land to retard the flow of water and conduct it to an otttlet which
l should be permanently protected from erosion. 'l`erracing should
._,,  l always be combined with good cropping practices and the soil treat-
   _ ment necessary to produce good crop growth. otherwise terraces
K   rannot be fully effective. Practices that should be adopted for all
{ `  terraced land are as follows:
if   l. Lime and fertilizers where needed.
A2. i 2. Legumes and grasses in crop rotations.
il  A Ii. \\’inter cover crops to aid in controlling sheet Cl`()Sl()l] be»
_ Q tween terraces and prevent leaching.
` sl. Contour cultivation to facilitate terrace 1112lil1L(i1)ill1CC.
, 5. The conservation and use of animal 1l1Zllll1l`CS and crop
residues.
J VVHERE TO CONSTRUCT TERRACES
.   il`erracing may be used to aid in controlling erosion on produc
  tire soil. 2lll(l as the initial step in restoring eroded infertile soil to
ii . a productive condition. 'I`erraces are advisable on slopes having an
average grade of I2 percent (12 feet of vertical drop to 100 feet of
witll   horizontal distance) or less. that are subject at any time during the .
ts ia 1 crop rotation to serious sheet erosion or gullying and are not too y
glopt y hitflly depleted of fertility to be econoniically restored and lllillllr l
JW lilllwtl. Fl`(‘(]llCl][l}`, terraces may be used to atlvantage tm Sl0]DC‘S ill  
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  ip"
10 K€}Ifl(('/€}' Extension Circular N0. 304  ._
 
tops of hills where grades are not in excess of 12 percent, as a meant  rp (Mw
of keeping ridge water from eroding steeper portions of the samp  Qi (__uC(
slope at lower elevations. \V11€1`C t€l`l`2lC€S 211`€ bllllf UU H $l0l)€ Htl-   (LMI
jacent to bottom land. they not only aid in controlling erosion tm   QIAW
the slope but protect the bottom land from excess of water from the   I
slope. since the water collected by terraces into one outlet can hr; Q. \·
conducted across the bottom to a natural drainage channel.  
TYPES OF TERRACES  
Two distinct types of terraces are used in controlling erosimi;  
the bench terrace and the ridge terrace.  g
Bench Terraces. Bench terraces change the slope of the laml  
into a series of benches. They are now seldom used except in place  
where necessity requires the cultivation of very steep land, becattst  ¤~
they involve too much waste land between the benches and becaust   A
of the difficulty of moving teams and farming equipment from mit   since,
bench to another.   chant
Ridge Terraces. Ridge terraces are simply ridges of earth   A low
thrown up across the slope at intervals, the distance between them   Tlltil
depending upon the SLGCPHQSS of slope and the character of soil.   $l10Ul·
Since ridge terraces are not used on steep slopes, they can be can- {  A
structed and maintained by moving earth up hill or down hill at   <`l11¤11l`
required. The ridge is wide enough to permit one or more rows th   OY 101
be planted on it thus avoiding waste land. Ridge terraces may bc   V€
from upper to lower side. Those having a width less than 18 feet  Y QS PY?
are narrow—base terraces, while those 18 feet or more are broad-base  E (l€$U`U
terraces.   He
\tVide terraces are to be preferred, since heavy farm macliinert Z  lance
may be operated over them more easily and they are less apt to bt   race ri
broken. Terraces may be increased in width by throwing earth ltr  g is 18 ;
wards the middle of the ridge when plowing. Terraces more than  jx tlepen
20 feet in width cannot be economically constructed or easily main-  {3 strttcti
tained on slopes having a grade greater than 12 percent.   measu
_‘ alwars
DIMENSIONS FOR BROAD-BASE TERRACES Z js lmig.
lnsufhcient height and width are probably the chief causes ttl  Q Measit
breaks in terraces. Terrace systems must be so designed and colt  E the to]
structed that they will not be overloaded with water in periods ttl  `l Wy
maximum rainfall. Experience has shown that it is not advisablt   consist
to build terraces in Kentucky that have dimensions. when tl10r0l* 0. watgy
settled. less than those shown in Figure 3. Terraces to be used ZW  s wh{(;h
reclamation measure in connection with pasture or meadow ettttl  _ t·h;mm

   _ Soil E}`O.YI.()71 and [ls Con/ro! 1 I
lm -;  other soil improving practices should be of the dimensions indi.
lllf  f;* (metl, because lieavy rains may occur before vegetation has been
all  if tisiiiblisliecl: also because in most instances the land will later bg
llll  _. pltiwetl l`or a cultivated crop.
tht  
btr   \ \\ ....
-  
. E
  Ri \~ \ \\
 2. * ` `
O".   Back Channel Ridge \
I {  élapo. ` \
 Y 3¥¤6' 3¢¤5' l5' ro l8'
tml  V
lC(‘~   Fig. 3. Suggested dimensions for newly-constructed broad-base terrace.
ust  Z
ust  :_ A wide water channel with a bottom level crosswise is desirable.
out  e since, other things being equal. this increases the capacity of the
i channel and permits the water to flow in a wide, shallow stream at
trtll  i. a low velocity rather than in a deeper stream at a higher velocity.
  The bottom width of the channel should not be less than 3 feet and
rem   _
mil   _‘_. should be 5 feet where the terrace length exceeds 900 feet.
sou-  .Y A back slope should be made at the upper side of the water
lm  . channel above the terrace to remove the vertical wall left by plow
sta   or terrace grader, to increase the capacity of the channel and to
·bc   decrease the tendency of the soil immediately above the terrace to
uhh   move down into the channel. The back slope should be as narrow
fetl — as practical when terracing in l)2lStL11`€ or meadow land, to avoid
mst E destruction of vegetation, but in no case should it be less than 2 feet.
  Height of Terrace. The height of a terrace is the vertical dis-
mt Q.  tance from the bottom of the water channel to the top of the ter-
i bt  ? race ridge. The minimum height recommended for a settled terrace
lit,.   is 18 inches. Newly constructed terraces will settle 2 to 6 inches,
han Z  depending on the amount of packing the soil receives during con»
iaiii.   Strtlction. The height of a terrace ridge should be determined by
_ nieasureinent, since it is usually less than it appears to be. There is
_ always a tendency to build terraces with insufficient height which
V ls larrrel * res Jonsible for the overflow of rid res durinvr heavy rains.
F· _ _ S m .
.5 til · Measurements lor height should be made only alter loose earth at
[t_)ll  Q lhe top of the ridge has been well tamped.
lS<‘l   Wfd//2 of Terrace. The total width of a broad—base terrace
ablt _ consists of the base width of the ridge, the bottom width of the '
»r0l‘  y. water channel above the ridge and the width ol' the back slope.
as;} wlnch is the horizontal distance from the upper side of the water i
· `ll'lllll*ll la ~` ·` · ·· · · · · " `
ant , t ( c o t ic (lll rinal nound level aboxe the channel. lhe width
» l

 ‘  
12 Keri/itc/ty Exlcnsiort Circular N0. 304  
of the base of the terrace ridge is very important, since it determines   (md
to a large degree the anrount of work required to nraintain tliq   mw
terrace. A terrace with a base less than l5 feet in width, even thi,   I`. H
the height. may be adequate, can hardly withstand the leveling  _ Sim,
effect of farm implements during a period of cultivation.   mm.
TERRACE GRADES   1* mi
Broad-base ridge terraces should be so graded that the water  T ··i
channel has a fall towards a selected outlet of 2 to 6 inches for each   r;
100 feet of terrace. In some instances, because of lack of a suitable  if L°“€
outlet, level terraces are constructed which must hold the inrpountl.  
ed water until it is absorbed by the soil. Level terraces should be  
built only where terraces are short, the soil permeable and slope ol  r
the land gentle. Usually all these conditions are found only near  gp W.,
the top of a hill. Level terraces