xt70k649qf7q https://exploreuk.uky.edu/dips/xt70k649qf7q/data/mets.xml   Kentucky Agricultural Experiment Station. 1922 journals kaes_circulars_001_2_129 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. 129 text Circular (Kentucky Agricultural Experiment Station) n. 129 1922 2014 true xt70k649qf7q section xt70k649qf7q ;·~;_  Q   (// *-f   I
 V Extension Division
{ THOMAS P. COOPER, Dean and Director
Q . . .
Q 2 e.r. wif
.   By
Lexington, Ky.
I May, 1922
. I’\lI¤IisImd in <·m1i1¤‘•·li·»1i with the iIRI`I(‘IlIIllI'£lI ¤-xtiiiisiuu work ¤·;i1·i·i·—·I
Gu IW cO`0I1Ol`1\IIIlc·;;0 of A)II`I&‘IlII\lI`<‘, I`lII\'t‘I'>II)' of l{¤~1iiu··1ool<, "Soils," gives the estiiuute that tl1e sediiueut deposited
uiiuuully i11 the Gull? of Blexieo hy tl1e Mississippi River would
eover 2158 squure 111iles to the depth of 0110 foot.
I Wheu these CIIOPIIIOIIS losses ure eousidered iu eo1111e1·tio11
with tho fuel. thut. p1·ueti1·z1lly tl1e eutire SllI`I`ilk'O of I(L‘IIIII\'l{}' is
rolling, it 11111s1 110 1·1·;11iz1·11 Illill soil 1‘1'0SI0ll is il prohlcini of primo
¤1111<>1‘lz1111·e to tho I`ilI'IlICI`S ol` the stutc. `

 4 Circular N0. 129 Q
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s,:j__.·» _ J V   ·,.‘i_ ~·—- {,2, >-i“i;;,§_'·`-     Z: r  eg i F      
Fig. 1. A scene not uneoniinon in Kentucky. i
There are two general types of erosion, short trosion and  
gullying. {
Sheet erosion, as already indicated, is the more or less uni-  
form washing of the soil in which no distinct gullies are formctl.  
Because it is so uniform it is often allowed to proceed until inorc {
or less damage is done before measures arc adopted to control  
it. XVithout doubt, more plant food is removed from the soil i
in this way than is removed in crops. In the removal of our
inch of surface soil from an acre of average Kentucky soil. up A
proximately 150 pounds of phosphorus, 300 pounds of nitrogen E
and 3,750 pounds of potassium are carried away, This loss i`vP· *
resents the most available plant food of the soil, because the
finer particles of soil and the part of the soil richest in luumis ·
are the first to go. Leaching of soluble plant food in under- U
· drainage water is greatest where erosion is greatest, because ,
€I‘0SiO11 is gfeatcst Where there are no growing crops to pI`0t€Vf `
i A t

  Soil Erosion 5
{ the snrfaee, partieularly during the late fall and winter. Grow-
t ing erops prevent the leaching of soluhle plant food by using it.
  'l`h··re are two phases of ynllying. One is the lzcadwator
r t phase, in whieh slope of the gsnlly at its head gradually works
A   up the hill. The other is the orrr»foH type. This type is found
  in grassland aml in other lands where the surfaee layer is more
__   resistant to washing: than the sul»snrt`a<·e layer. The water
    "eats" haek under the more resistant layer until it breaks off
    in large pieees, whereupon the proeess is repeated.
"   The ]\l't‘\'(‘llllOIl {mil Stopping of these \'Zll‘lOllS forms of CFO-
__·   sion will he disenst later.
Q}.: {
E E A statement of some of the laws of moving water will serve 1
'Q to impress upon landowners the destrnetive power of water and
  to suggest means of eontrollingr erosion.
  1. If the rate of flow of water is donhled. the erosive power
is inereased four times. (lirosive power varies with the square
1 1111*l of the veloeity.)
_ 2 2. lf the rate of flow of water is doubled, the amount of
    material of a given size that eau he earried is inereased thirty-
I Imp 1 two tunes. (Amount of material that eau be earried varies w1tl1
(WM i the 4th power of the veloeity.)
nl, my f 3. lf the rate of flow is donhled, the size of partieles that
of mpi   (`?111l1€‘ Carried is inereased sixty-four times. (Size of partiele
(ip M,. A that eau be earried varies with the 5th power of the velocity.)
itrogeu It follows that two very important considerations in pre-
»ss rep- venting erosion are to deerease the amount of water that runs
ise the ‘ off and to eheek the rate of tlow of that whieh must neeessarily
lillllllls .p PHSS away as surface run-off, The amount of surface I‘111!—0t¥
under· varies from nothing in regions of low rainfall and porous soils
l>C€211l‘“ V1 HS lnneh as 50 per eeut; of the raiut`all iu some regions ot high
protevt rainfall. It is very high in Kentnehy. _

6 Circular N0. 129 i
Perhaps more important than reducing the amount and the ki
velocity 0E the run-otf is treating the soil so that it will resist
the washing power of moving water. A
The most etteetive means of preventing sheet erosion is to l
keep the ground well covered with some kind of growth. A vege- l
tative covering serves in many ways to prevent erosion.  
1. The roots of plants hold the soil against washing. E
2. Growing roots cause the soil particles to tlocculate; _
that is, assemble themselves into granules or crumbs, \\‘hi<·h _
are larger and harder to move than single grains. 'l`his condi- j
tion makes more pore space in the soil to take in water and re—
duce surface run-0E.
3. Roots of plants when they decay leave passageways for X
the water to enter the soil, thus reducing the amount of surface 2
4. A vegetative covering reduces the force with which the Q
rain strikes the soil. The heating of the rain breaks down the  
crumb structure referred to in No. 2, and thus reduces the Y
amount of water that can enter the soil, while the breaking down ‘
of the granular structure makes the soil more easily washed. ,
5. A vegetative covering checks the rate of flow and thus  
gives the water more time to enter the soil. .
6. If the soil is kept occupied by growing crops, more root< it
will be present which on decay will form humus, which in turn A
increases the water holding capacity of the soil and also helps tc .
granulate the soil, a condition which, as already stated, helps t·· ,
prevent erosion. ‘
Expressed in practical terms, this means that the farmer c
should adopt aeropping system that will keep the ground oc-
cupied all the time, or as nearly all the time as is possible. The
cropping system should provide for deep rooted crops, such a<
clover, and fibrous rooted crops, such as the grasses, wheat and _
The best crop for controlling washing is permanent grass.
There is much hilly land in the state that should be kept ill

 A Soil Erosion 7
A permanent pasture. Ilueli rolling land tllflt is now cultivated
mp = ]‘(*{[lll2lI'l}' should he kept in grass a large part of the ti111e. \\'here
dsl good sods are plowed under, t`airl_v steep lands may he eulti-
‘ vated for a year o1· two without serious washing if a wi11ter
i eover erop is used. Une of the reasons why it is often so difficult
i to I to grow grass on steep la11ds is that they have lI<'(*ll impoverished
ig'}. i hy eultivation and (‘l'f>Nl<¤l!. Many of these poorer lands will
  grow fairly good redtop a11d .lapau elover if treated with pl1os-
phate fertilizer. The poorest lands in tl1e state can he made to
i¥·‘1 . proqluee good sweet. elover if treated with limestone and phos-
1i·‘l¤ . phate. After sweet elover has lN‘|’ll grown for two or three years,
udi- j grasses eau illt‘ll he grown. trlreliard grass makes an exeellent
l1‘v· companion for sweet elover. and i11 the Bluegrass region blue-
grass thrives with it. Sweet elover and grass make a good com-
: for x hination for reelaiining impoverislied land.
`fim ·. Even where land is to he eultivated every year a eropping ‘
  system should he adopted that will keep tl1e ground oeeupied.
1 il1·‘ 5 That this is not tl0Ilt‘ is shown hy the eensus figures. A little
1 the _ more than four million aeres of land are planted t0 summer
. the Z crops; eorn a11d tohaeeo amounting to 3.887,000 acres. Assum-
·    I
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· . . _ · r ’ ‘ ` ` l‘ \ ·  
Fig. 2. Rye grown for cover crop on eroded land and pastured.  
Note the rye in gullies.  
serves also for the cover crop, If nitrogen and potash fertilizzl-  
tion are needed for the tobacco crop, these materials can be addol  t
in the tobacco hills in the usual way. Not only is this lll(‘lll**ll  Q
better but it is usually cheaper than buying mixed fertilizers.  
Rye is probably the most reliable cover crop for QCll€l`ill  
use, altho wheat and barley may be used. Crimson clover li  ii.
fairly satisfactory in some parts of southwestern Kentucky.   .·~.
Often it is desired to seed grass and clover following a cul-  
tivated crop. An excellent procedure is to sow a cover <‘l‘l.>le.
   _‘i Sleping lands that wash should he plowed, planted and eul-
  `Q  liyated on the eontour; that is, aeross the direetion of the slope.
fill, l.  Tllnw operations, when pertortned with the slope, make furrows
     V wltielt in¤·rease the run»ot`t` ot water. hut, when perforined on the
   _A Contour, the l`urrows ltold the water and give it 111OI`C time to
‘ ,.  enter the soil. ·
L  ` The tinte and eltaraeter ot` plowing intlueuee erosion. Soils
l    ` should not he plowed in the tall for spring planting, if they are
    liahle to wash during the wiuter_ but should he protected hy sod
Lmwl  an (li cover erop. bontetiines, ltoweyer, a good sod broken 11.1 U18
 y tall will not wash during the winter, altho on a deeided slope. t
fliwwl `. Q The t‘ll§l]'.;lt·lt_'l' of plowipg may i eoutrllttttel to \\'ilSl1ll1L`·
Nw is  A ·lli1lll>\\' plowing on a slope is t·ot1du<·1\‘e to \vt1sl1111g. l)lO\\'111§
'  · Slltllllkl he front ti to 8 iuehes deep, lt. is not unusual to see at
2 (ou]-  _ llllllly plowed layer oil soil entirely removed from il slope by 21
‘ x of i lU¥l\`}` l'illll, 1)l(>\\`lllg` to the saute tleptlt year fitter )'Ci11‘ IIHIY
ml,1,h`_  ‘ fwm il "lll<>\\' Sole," or hard layer of soil whieh prevents ready _
  with  V l’€1`<‘0l&1tiott of water and eauses a greater rnn—0iY.

 Q .
10 Circular N0. 129 ·.
Sometimes, where it is necessary to cultivate steep lznnls I (
rather frequently, erosion nniy be cheeked to sonie extent hy  { (
leaving sod strips ten or fifteen feet wide at intervals on the   1
contour. i 1
Tile-draining of wet sloping lnnd will greatly reduce erosion `_
by reducing the surface rnn-oil.
Under some conditions deep plowing, contour enltivntion T
and eover crops fail to eheek erosion. In this event terraces nniy  
be used.  
Terrzieing eonsists ehiefly in so nltering the slope of the hind  
by throwing up obstructions in the {orin of ridges of ezirth aieross  
the slope as to retard the tlow of waiter or to hold it nntil it is {
absorbed by the soil. These ridges may be enlitvzited or nniy be {
sown to grass and left in permanent sod.  
  _1 · fi V    
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dzé-.   " ,f}jT·*€i?_EE  
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    //»  ’7//· ii   ·
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\,'*'  / { /4 /] (\\l\\ `\ \\ \\ \\ "_`i-···—-·~~·--  ·
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`,i¤'  wi'//{ ·ll `~ ~*}*‘>§€¥i~. "L "`  ·  2
  f zu !2\ `\¤`~{•>§Q*s1—r.
Fig. ll. The bench terrnev. _ `
TilC1‘C 21I‘•3 t\\'0 distinct types of tl·1·1‘;r,ees; tho lwneli i,0l'1‘1\U•J  `
(Fig. 3) und the ridge terrnee (Fig. 4). The hein·h terr:n·e

 ` `
1 Soil Erosion 11
lS I (·h;mges the slope ol` the lauil into as<~1·i<·s of benches, After sev-
ly  ll (Will }`¢’2ll`S Ul- l'lllll\lillll|ll, ll(‘ll('ll('N l|<'('Ulll(‘ lt‘\'('l ()]l [[(*(•()[]])t of the
IC   py-netis when plowing ol` ilirowiuz the soil ir.?~1:.'·\;.J<‘·}T  S
iiiii x ‘ `    if  ‘·i¥·’%${'·:·?—° .Y€`~*¢ P *1Zl* *  i`S‘F—.,\im .  L
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‘·— ’~ *4 *' `. - e   '·¢E‘=·t¢ ·..-~.=`·;;itt·._‘!<_§ Q, .,,§__   A: ., _; _, ._.., a., ( .  _
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7,ry`LA\§   \g·'P':`·-;"_v     v r;;?_-_*(.· ly;}. IT ` I f,  R
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(V l° .>·a`   A· ·. · ·.7;_. s . *·'is` . ‘ ·  
Fig. 5. Narrow—base ridge terrace in Mason County, Ky.  
not possess any advantgc not possessed by the broad-base terrace  »,
and under ordinary circumstances is less desirable than the _
broad-base type. However, when laid out level, it is soinetiniei  i
successfully used on very sandy soils that are capable of {llJSOl`l)’  I
ing large quantities of water.  
The broad-base terrace is built from ten to fifteen feet wide  L
at the base and is at least fifteen inches higher at the center f
than the upper edge of the base. As already stated, the broad- _
base terrace may be laid out level or with a fall not to exceed  ;
, p six inches to one hundred feet, to carry the water at a IOW  i

 ‘ Soil Erosion 13
1.11 ; v0l01·111· 10 :111 ()llll<’l :11 1111- (*1111 0f 1110 ridge. ’1`hc i`0rmer1s called
mi  1 llltf 1(f\'('l·l`i(l{I¢1 1<·rr:1<·c aud 1hc latter 11 graded-ridge terrace,
11 1 — l·Zi1h0r 101·01 or {I1'211lL‘O1=T!;R2Ac£.
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tll1l\‘$ _ ;H;;’g1Z&’1.1;r13lmT¥,$@§·@:,@§< 1i1Q*j*Q _, $#1 ggfqvg/:_
 . 11;*;;,1111~ZDt;111i¤¢¢i1M/;1m§,;·1l§11'Q 511;,1*5 y,,·g 76 ·”¤71w;j,p I  ~
1. 3»=1‘1\‘5E/E ~= ·`-E—‘-tw- `—\ *1 ;
TOT)- .· :1%M@19;@·,§s1:¢$.@2%1#!’r4191221,%*3?@'é`¤’4$,'2E15F,nf \`”"`>’·’—'·‘1·. 1 #
leutcr 1 1*1;. 11. '1`i10 11111111 101·r:11·0s.
lgcccd Tll0 l>1‘0:1d»11;1s0 {fl‘i11l1‘1T-l‘11l;_!`1‘ l1‘1`1'211‘(}. 01* the Blzlllglllll t0I`-
1 low race, is similar 10 the 111*0:1d-base 10v01—r1dg0 t1‘1`l'2lCC, with the ex- ·

 t .
14 Circular N0, 129
eeptio11 tl1at the terrace is given a very slight fall so that the y
water is carried around the hill at the upper side of the ridge in TA 
a wide Sll`Cill11 at a very low velocity. lt. has boen found that f
average soils are not SL‘l`l()llSl}' washed in broad terrace channels {
where the fall does 1lOt exceed 6 inches in 100 feet, and it is re- ‘
comniended that this t`all never be exceeded. The terraces may T
be laid out with a unit`orn1 or a variable grade. The best results
are obtained where the variable grade is used si11ee it tends le
prevent tl1e accumulation of the wate1· at the lower end of the
terrace. Variable grade means that tl1e slope of the terrace is
not uniform from OIIC end to the other, but that the rate of fall =
is increased from the upper to the lower end at intervals. This
variable grade enables the channel to carry water at theilower 1
e11d faster than at tl1e upper end. thus preventing an accnmula-  
tion at the lower end where there is the most water to be carried.
The Mangum terrace possesses all the advantages of th.- ¢
broad-base level-ridge terrace with the exception that some of _
tl1e fertile soil may be removed from the tield. \\'here the fall V
of tl1e terrace does not exceed that reconnuended in this circular.
_ the amount of soil removed from the field will be negligible. Un
account of the movement of water there is very little chance “
that it will break over the terrace, which is a very important
consideration. The cost of terracing a iield with the variable- _
grade terrace will be loss than with the level type since the .
distance between terraces can be made greater. From table No. i
1 it will be $0011 that the vertical drop between terraces is T foot
for the Mangunt terrace on deep, porous soil with a slope of 15
feet per 100 feet, while in table No. 2 the vertical drop for a
level broad-base ridge terrace for the same conditions is 3%] feet. i
The Mangum terrace requires an outlet for the water. Where
there is 110 outlet the level-ridge terrace should be used.
In regard to the typo of terrace to be used in Kentucky tlw  
following reeoininendations are made: Q
1. The bench terrace {llltl the narrow-base terrace should O
be used only 011 steep slopes a11d very porous soil, Since stoop
slopes are best left i11 permanent pasture or woods, and since

 ‘ `
A Soil Erosion 15
ae ; tliere is very little sandy soil in the state, these two types of ter-
iu raee are rarely to be reeommended.
at   2. The broad-base level-ridge terraee should be used only
·ls ‘_ where no suitable outlet ean be seenred for the Mangum terraee.
·e- I tl. \\'here the broad-base level-ridge terraee is used, tile
ay K should lie installed to remove the water from the upper side of
lts l the embankment at draws and deep gullies.
liv P 4. The Blangum terraee with variable grade. altho not
lie l quite so etiieieiit iii preveiitiiig erosion as 21 properly COIISTYUCICI1
is level-1·idge terraee. is mueh less apt to give trouble. and for gen-
`all i eral eonditions is the most praetieal.
his l
my i Best Time for Constructing Terraces
M. Terraees may be eonstrueted at any time of the year when
ih`} the soil is in proper eondition. The best time is during the
_ of _ months of August and September. beeause of the opportunity .
HH 4 of planting a eover erop to proteet the freshly moved earth dur—
hm E ing the winter. During these months the rainfall is usually
Un lighter than at any other season of the year, and as heavy rains
HM before the terraee has settled may eause serious damage. this is
mm . the sat`est time for the work.
mh)- V- Equipment Required
SK   1. Farm level.
fwt 1 2. Rod and target,
E15 3. 3lL‘2l$l1l`lllg line.
or H »   Stakes.
foot. Ir o. Illow.
how - G. 'lerraee drag or grader.
7. Slip seraper. T
The most aeeurate instrument for determining the line of
v_ the terraee and the one with whieh the work eau be done most
v the I rapidily is the surveyor `s level. Theie are several inexpensive
ip farm levels on the market and the instruments are very useful
iould for other purposes, sneh as land drainage aml building eonstrue-
steep tion. An adjustable rod for reading elevations ean be pur-
sinee chased with the level. Some l`armers have made and used various `

 { iu.;
16 Circular N0. 12.9  1
triangular devices with levels attached for determining the line  
of the terrace, but where 11 variable grade is desired these tools _
are impractieable.  g
A measuring line for getting the correct distance from one  
point 011 the terrace to the next should be provided. Since these  A
points should be either 25 or 50 feet apart, depending on the ‘
regularity of the slope, 11 s111ootl1 wire 25 or 50 feet long with  L
loops i11 the ends lllily be used instead of ll tape or chain.  ·
\Vooden stakes for marking the points which have been lo- `
cated are required. A large 1nnnbe1· of stakes is not necessary,  1
provided the men locating the terrace 11re followed closely with  T
a plow to mark the line of the einbankment. 'l`obacco sticks niakc  
excellent stakes.  A
A turning plow or disk plow is used for loosening the soil  
so that it 02111 be more easily moved by the grader or terrace drag. V?
The home made drag o1· terrace drag is most often used for  i
b11ildi11g up the terrace. Other i111ple111e11ts sonietinies used are  
the four-wheeled road grader or the eoniniercial ditchc1· and  ;
grader. A cut is shown (Fig. 7) of 21 reversible terrace drag  
which is very efficient as a road drag as well as Z1 terrace drag.  if
W The slip scraper so111eti1nes is used \\'l1Cll it is necessary to  
b11ild tl1e embankinent higher at points where the terr11ce crosses  —
a draw or gully.  ‘·‘
Prellmlnary Survey  
Some time should be spent i11 a preliminary survey of the 1 
field to be terraced before actual work of laying out is started. it 
particular attention being paid to the following points;  `_
1. Outlets.  A
1 2. Slope of the land.  
i 3. Character of soil. 1
4. Length of terraces. _ 
I Outlets  
If water can be carried into a woodland for final disposal.  Z
it will cause little or no washing. The water 1nay be ca1·rictl »
to a roadside ditch or gully, but this water course should be pro- ;
tceted from additional erosion by means of dams made of rock ; 

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18 Circular N0. 129 i
or other materials. Very often a draw eau be sown to grass and l
used as an outlet without danger of erosion. The best method of ,
disposing of the run-oil is thru a natural outlet.  ;,
Erosion, at the end of the terrace, where the greatest  
amount of water tiows, is prevented by sowing to grass the last  ·
one or two hundred feet of the area carrying the water. This  "