xt7q833mxv3k https://exploreuk.uky.edu/dips/xt7q833mxv3k/data/mets.xml   Kentucky Agricultural Experiment Station. 1969 journals 187 English Lexington : Agricultural Experiment Station, University of Kentucky Contact the Special Collections Research Center for information regarding rights and use of this collection. Kentucky Agricultural Experiment Station Progress report (Kentucky Agricultural Experiment Station) n.187 text Progress report (Kentucky Agricultural Experiment Station) n.187 1969 2014 true xt7q833mxv3k section xt7q833mxv3k       5* ~·-· ‘   _ ,V,( j  #~{~‘—   , ./,, -   fsf 7%- I
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N Of] 'ILLAGE
Its Influence on
SOIL MOISTURE and SOIL TEMPERATURE
by
R. L. Blevins cmd Doyle C00|<
Progress Report I87
UNIVERSITY OF KENTUCKY
COLLEGE OF AGRICULTURE
AGRICULTURAL EXPERIMENT STATION
Lexington

 
 CONTENTS
Page
Introduction ................................... 5
Experimental Procedure .......................... 5
No-Tillage Soil Moisture .......................... 6
No-Tillage Soil Temperature ....................... 13
l Conclusions ................................... 14
References ................................... 15
3

 
 NO-TILLAGE — ITS INFLUENCE ON SOIL MOISTURE AND SOIL TEMPERATURE
 
By R. L. BLEVINS and DOYLE COOKU
As the demand increases for higher levels of crop production, conservation of soil and
water resources becomes more important. The modern farmer must continually seek cultural
practices which increase profits and at the same time conserve natural resources.
For these reasons, a relatively new production management system called "no-tillage"
has been adopted by many corn and soybean producers and is receiving widespread attention
from agricultural scientists.
No-tillage offers a decrease in labor costs and at the same time uses the soil and
water resources more efficiently.
When one is trying to intensify crop production, a very important factor is more effi-
cient use of water. No-tillage production is a positive step toward increasing water use
efficiency and protecting the crop against short-term droughts. No-tillage increases the
infiltration capacity of soils, hence, decreasing the amount of surface runoff and serving as a
very effective erosion control measure.
This publication deals primarily with the effect of no—tillage systems of crop production
on soil moisture and soil temperature. (
( EXPERIMENTAL PROCEDURE
' Soil moisture was measured on experimental corn plots, using the neutron back-
scattering method (3) during the 1968 and 1969 seasons. During the 1968 growing season
soil moisture was monitored at a depth of 9 inches between corn rows under chemically-killed
bluegrass-sod and under adjacent conventionally cultivated plots. Under conventional tillage
the previous cropped residue was plowed under to a depth of 8 inches with a standard mold-
board plow and disked to establish a seedbed. Chemical weed control was used in lieu of row
crop cultivations. In no-tillage, the bluegrass sod was chemically killed and corn was
planted with a modified planter that disturbs only a narrow band of soil, just enough to allow
placement of seed and subsequent coverage.
During the 1969 growing season soil moisture was measured on (a) conventional tillage `
plots, (b) 1st year no-tillage, sod-killed and (c) 2nd year no-tillage (corn stover from
previous year returned to surface and fall seeded rye chemically killed at planting time). To
acquire a higher degree of accuracy, gravimetric moisture determinations were made on
0-3 inches, 3-6 inches, and 6-9 inches layers of soil. A neutron backscattering device was
used to measure soil moisture by volume at depths of 12-, 18-, 24-, 30-, and 36—inch depths
to obtain a seasonal distribution of moisture with depth in the soil profile. All treatments
were replicated three times.
The 4-row experimental plots, such as were used in this study, are considered large
enough to preclude appreciable lateral movement of soil moisture from adjacent plots to
points of measurement in the center of the plots.
5 Assistant Professor, Department of Agronomy, and Advisory Agricultural Meteorologist, ESSA , Weather Bureau Office
for Agriculture , University of Kentucky, Lexington, respectively.
5

 These plots were located on the University of Kentucky Woodford County Experimental
Farm in the Inner Bluegrass Region of Kentucky. The plots were on a Donerail silt loam,
gently sloping soil. This soil is a deep, moderately well—drained soil developed from phos-
phatic limestone. Mean annual precipitation for this region is approximately 45 inches. V
NO·—TILLAGE SOIL MOISTURE
It is generally agreed among soil scientists (6, 8) that soil covered with dead sod will
have a greater infiltration over a growing season than the same soil after normal plowing and
cultivation. The presence of the undisturbed but decaying plant roots in the soil and old root
channels may serve as a ready avenue for water infiltration into the soil (1). This enables
the soil to store more water following appreciable rainfall.
Soil moisture is normally lost from the plant root zone by evaporation from soil, run-
off as surface water, transpiration by growing plants, and percolation to depths beyond the ·
normal root zone. One would expect that a killed sod cover would reduce soil moisture losses
due to evaporation and runoff. When compared with normally cultivated land, the sod cover
should have little effect on the amount lost due to transpiration. Percolation losses may be a
little greater under no-tillage conditions, owing to increased infiltration of water during
periods of rainfall. As shown in Fig. 1, except during the first few measurements, soil
moisture at the 9-inch depth was always greater under killed sod than under adjacent culti-
vated ground. Total rainfall during the 1968 season was near normal. Distribution of rainfall
45 1 1 1 K   www V *1 *‘** "1'**T’ W ’1’"’" ‘*"lYT4‘
  .
l 1
35 1 as !`1·~.- E     E ~ ~   ·--~-~     -~~-
9 1 I
Z l l
O     l
f 1 · 1 `~ .
E 1 `\ l ~/‘
o 25 j rr 1   M b' rmi I rr\r~ in  F\~ r ·· ~· 4j
li   Z \ U \ . \
Q` 1   \ · `• ` | ` ¢'\•
:+ · l \ { ‘ ‘ I
; 1 1 1 s x I \ I
T, 1 1 1 \ I \` p \ I
> I5       " fr`;
1 l l 1•
1 ···· Under killed sod
l ""‘ Under cultivoted ground ` ` 1
5 { 1 1   1 1 . 1 e 1 ei 1   ieee ii cr.. rmnn
l0 20 31 l0 20 '%O 10 20 3l l0 20 31 10 20 30
May June July August September
Fig. 1. — Soil moisture at 9-inch depth, Woodford county, Kentucky. No—tillage experiment, 1968.
was such that no serious moisture deficiency was observable, as indicated by plant response,
iuider either no-tillage or conventional tillage conditions. On one occasion, on July 12 prior
to showers on the 13th, conventional tillage corn leaves were observed to "curl" to a minor
degree during the afternoon while no-tillage corn leaves showed no visible effect.
6

 All the tests under killed sod were conducted with nearly continuous sod cover.
There were few bare patches. Most workers agree that, owing to soil compaction in the
areas where no sod has been grown, unless a fairly continuous sod cover can be attained
prior to application of the herbicide the next most favorable soil moisture environment for
growing corn is in a well cultivated soil without weed competition.
During the 1969 growing season, rainfall distribution was near normal (except for
August) with 3. 78 inches in May, 4. 61 in June, 4. 37 in July, and 5. 96 inches in August for
a total of 18. 72 inches. This represents about 42 percent of the mean annual precipitation.
The 5. 96 inches for August is about double the normal monthly precipitation for the month
of August.
l Soil moisture in the top 0-3 inch soil layer under no-tillage was significantly higher
than that under conventional tillage plots throughout the entire growing season (Fig. 2).
40  { A H
——.,____ ,»• ~`_ o-3 DEPTH
38 fg " `\` Conventional •—•
x N -t'l| -
u 36 xk />·"°*q·_ ._ 2.... y.NZ-l'..iZZ Z.;
cr 34 / _/’ ·—-
D \\L/ \ ’;z*€\\ "‘
gu 32 V \(\x‘
O \
E 3O \\ A
li   `\ II, """`
LU 26 \". x' ’ "`°`·= ··
¤ x ~. » /
E 24 \ \ / /
¤L x ,/' / .
l.1.l 22 \ `V /
§ zo \\// '
o
> is g
C
we E
3.o  
2.o 2
H _ Cl
_____ _ ______ ___ ___._....... ---- .... - ........... - .l... --l-Re·2*eU- 1.0 g
ooli
2026l7l3l725l7l3l9253l6l2l82·<1305ll17
May June July August Sept-
Fig. 2.- Soil moisture (O- to 3-inch depth) under 3 methods of soil management for com production. Woodford
county, Kentucky. No—tillage experiment, 1969.
This moisture difference was about 10-15 percent until a slight drought occurred during the `
1st week in August in which the moisture levels were lowered under all systems of tillage.
This difference between tillage systems in the 1st half of the growing season might be
anticipated because of the evapotranspiration factor. It has been well documented (2, 4, 7)
that in the early part of the growing season under conventional tillage, evaporation accounts
for a high percentage of water losses. As the aerial portion of a plant grows, a shading
effect is produced that decreases evaporation. The increased growth results in greater leaf
area, and transpiration becomes the key source of water losses. The mulch from the
chemically-killed bluegrass sod serves as insulation for upper part of soil profile, thus
reducing evaporation. High moisture levels were observed near the organic mulch-soil
interface. This zone of high organic residue content has a much greater capacity to store
water owing to its high absorptive properties. During the early part of the growing season
7

 49 3-e" DEPTH
38
36  Conventional •—•
`* __ No-tillage •---·• ‘
lé-J 34 b`\?°"“*`_`r,/%<`·" 2nd yn No-tillage o--o
5 `O`\C/ \\ *" ’(\"~
- 3O ` x / \—.
O \r X
Zi 28 b/
E 26 \ / *:%*1 an
“ \\ x "——
U 24 "
\ ¢
[lg 22 if
[L R /7
gu 2O ~\_ ,»/
.2
g 18 Q
> 16 5 _
E
3.0 _§
2.0 E
__ _______ ___ ________ __ ________ _ ____ ___-_ ---.1;B€rlf€'L- .... 1.0%
- ti-
O O E
2O 26 1 7 13 19 25 1 7 13 19 25 31 6 12 18 24 3 5 11 17
May June July Augi-1$t Sept·
Fig. 3. - Soil moisture (3- to 6-inch depth) under 3 methods of soil management for corn production. Woodford
county, Kentucky. No-tillage experiment, 1969.
40 0-e" DEPTH
38
,,6 Conventional •—•
~ 2nd yn No-tillage o--o
iQ M ,.·$$""`r‘$~ Nomiiage •.-.•
ia ·"—•y’ / \\
U) 32 (\\ /  
0 BO "°’ ‘ ,¢"°~\_
E V,/I `
e 28 gg X
Z \   W u
83 2-/1 " \  
LU gg *\} /
Q 20 U
  111 .
1G §
1·1 E
3·O 5
12 2 O gg
10-- --.-- ----- ----------- --------- - -_-- -----_-- ----1;Fi·¤i¤;¤1l-----..,OP§
. it
O O S
20 26 1 7 13 19 25 1 7 13 19 25 31 G 12 18 241 30 5 11 17
Way June July August Sept.
Fig. 4. - Soil moisture (6- to 9—inch depth) under 3 met-hods of soil management for corn production. Woodford
county, Kentucky. No—ti11:1ge experiment, 1969.
8

 40 12·· oapm
38
` Conventional •—•
36  • "4 , No-tillage •·--•
LU 34 `°~`•--""* -" \ 2nd yn No-tillage 0..0
§
5 ` `\\ ’;.`
* 30 \ —- _
2 x ,4/%;; `
I_ 28 /7
[
5 26 4%
E 24
L1.l
[L 22
tu
E 20
6 18
> 3
16 5
C
/ _
’2.o_§
·•-J
2-OS
.... --- .-.--.- - .-....... -- -- .-.- -- - ..-. ---- ----. ----I'-R§L"I·¤J'- .._.- 10-%
I ‘ E
O-Ott
20 26 1 7 13 19 25 1 7 13 19 25 31 6 12 18 24 3 5 11 17
May June July August Sept.
Fig. 5. - Soil moisture (12—inch depth) under 3 methods of soil management for com production. Woodford county,
Kenmcky. No—ti11a e e eriment 1969.
S XP 2
40 1B" DEPTH
38  Conventional •—•
_ ·_ ··••·`_ __ v--••~ No-tillage •··•
LU 36 ‘ `kw; `9<"•..--·---·•` 2nd yn No-tillage o--0
Dc 34  
2 “~`
U, 32 , __,.•.-_____
6 ·‘° _. Z" 
E 30 '_,,»’ . •
12 28
ui
U 26
E 24
tt
LL, 22
g 20
_1
Q 18 8
16 {:6
S
30;
(U
2·0€
1" R ' fall "
-------.---. .-- ---- - ---.- --- -.-- -- - --.---.--- -.-------€'U----- 1.0§
0-01l
20 26 1 7 13 19 25 1 7 13 19 25 31 6 12 18 24 30 5 11 17
May June July Au ust Sept
9
Fig. 6. - Soil moisture (18—inch depth) under 3 methods of soil management for com production. Woodford county,
Kentucky. No—ti11age experiment, 1969.
9

 40 24*· DEPTH .
38 Q:. Conventional •—•
-•Q •~,_ _____ No-tillage •-·-•
36 /.54;-=·¤ ;’8:;..--o•`Q~._•` 2nd yn No-tillage o--o
M 34 \<>Q`
LS 32
*_ I Ctdxx-3-1x3 $*1**111 i
_ LQ 30 ;-•; ;.8=—..-;» _-
O
E 28
P
2 26
lil
(J  
tz
{ 22
tu 2O »
g 18 in
6 2
> 16 g
/ ( Q
3-O .9
Ei
2.0  
-- .._. _- .___ ___ _.__ __,_______ - ___..... _,._______ ____ ____j;B=°»!i]_f§IL_,_ ·]_O`g
o.o at
2O 26 1 7 13 19 25 1 7 13 19 25 31 8 12 18 24 3O 5 11 17
May June July August Sept-
Fig. 7. - Soil moisture (24—inch depth) under 3 methods of soil management for com production. Woodford county,
Kentucky. No—tj11age experiment, 1969. ‘
AO ae" DEPTH
38 Conventional •-•
36 '_ No-tillage •·--•
LU 3(1 ·_ "*____ 1) _   V _•-_
[S 32 "`· 
l-
*2 iso
O
Z 28
Q 28
tu
ci 24
Di
Lil 22
it
M 2O
Y
3 18 8
O 16 5
> S.
1.1 C
12 3·O E
2·O  
`O_ ____ __ ________ _ _ ____________ _______ ____ ______ _____ _____ ________‘l;RginjalL__,0*2
· Doii
20 26 1 7 13 19 25 1 7 13 19 25 31 6 12 18 24 3O 5 11 17
May June July AUQUSY Sept·
Fig. 8. - Soil moisture (36—inch depth) under no-tillage and conventional tillage for com production. Woodford
county, Kentucky. No-tillage experiment, 1969.
10

 the O-3 inch surface layer of soil had a higher moisture content than even the fine-textured
subsoil (Figs. 6, 7, and 9). During the 1969 season, soil moisture for the soil profiles was
higher at all times for those under no-tillage.
The difference in seasonal moisture under the three methods of management (Figs.
· 2, 3, 4, 5, 6, 7) show no-tillage to be considerably higher in volume percent moisture to a
depth of 24 inches. Beyond a depth of 24 inches, systems of tillage or management had very
little effect on soil moisture contents over the growing season. The volume percentage soil
water at 36 inches depth decreased by 2-3 percent (Fig. 8) from May to September tmder
both no—tillage and conventional.
~ The plots referred to as 2nd year no-tillage were consistently intermediate to no-
tillage (lst year sod-killed) and conventional tillage in its seasonal soil moisture content and
distribution within the soil profile. The 2nd year no-tillage actually compares more closely
to lst year no-tillage because of a comparable amount of surface (organic residue) mulch.
The mulch for 2nd year no-tillage plots consisted of remaining residue from killed sod of the
previous years, corn stover from the previous crop and a rye cover crop chemically killed
prior to planting of corn. At corn planting time the 2nd year no-tillage had a heavier, but
less uniform, surface mulch than the no-till bluegrass sod plots. However, the vigorous,
succulent growth of the rye in the spring prior to being chemically killed removed some of
the water reserve in the plots. Corn harvest from these plots in 1969 showed yields of 117,
125 and 136 bgjhels per acre for conventional, 2nd year no-tillage and lst year no-tillage,
respectively.
A comparison of soil moisture distribution with depth and different methods of tillage
is presented in Fig. 9. Presented are moisture curves for July 25 (36 hours following a 1-
VOLUME PERCENT MOISTURE
1O 12 14 16 18 2O 22 24 26 28 3O 32 34 36 38 4O 42
Q `r—·‘r··r‘r
    -i·,   "‘¤.   ,»'°
  .`,—     ``·»   f'
6   ‘_»`  
    . `\
12 *     ..n1 ¤  . \
I 18 in 8.  
U Ys   _ \\
2 - .
T 24 V - )
I \ V ( ,
1- x
  `
gg •--• Conv. July 25
g o-0 Conv. AUQ. 8 2 ,
36 •...• No-Ti|,July 25
o---0 No-Til,Aug.8 i`
42
48
Fig. 9. — Soil moisture distribution with depth and different methods of tillage . Soil moisture
curves for july 25, 1969, and August 8, 1969.
2/Personal communication with Shirley Phillips , Extension Specialist in Agronomy, University of Kentucky.
11

 inch rain) and then again on August 8. Calculation of soil moisture to a depth of 42 inches
showed that the no-tillage plots contained one inch more soil water on July 25 than the con-
ventional plots. During the following 2 weeks of very hot and dry weather, water withdrawal _
was 2 inches for the no—tillage and 1. 5 for the conventional plots. No-tillage plots had a
larger reservoir of water to utilize during the period and made near optimum growth through-
out this period. Conventional tillage corn was showing visible signs of moisture stress by .
the end of the 2 weeks.
This decrease in evaporation under no tillage and the greater ability of the soil to
store moisture serve as a moisture reservoir which can carry the crop through periods of
short-term drought without strong moisture stresses developing in the plants.
None of the corn plots exhibited visual signs of moisture stress during May or June.
The Donerail soil has a potential for storing a reasonably large quantity of water because of
its moderately high organic matter content in the surface 10-14 inches and a silty clay sub- ‘
soil. To compare the soil moisture distribution with depth for no-tillage vs. conventional
refer to soil moisture readings for June 10 (Fig. 10). The 0-3 inch layer of no—tillage
VOLUME PERCENT MOISTURE
1O 12 14 16 18 2OQ2 24 26 28 3O 32 34 36 38 4 42
O r*··r····Tr·*··¤* #“
o".
é
r"
6 ` ’
\
12 \
an \`
LU
1 18 )
2 I,
T 24 (
I
E •-• Conventional
3O ·
LU •··• No-Tnllagc
O l
36 J
\
I
42
48 .Jun<21O,1Q6Q
Fig. 10. - A comparison of soil moisture distribution with depth for no-tillage vs. conventional from
soil moisture readings of june 10, 1969. Woodford county, Kentucky. No-tillage experiments.
treatment had 16 percent more moisture by volume than conventional plots. The curves in
Fig. 10 are also representative of the soil moisture distribution curves for two extreme
tillage systems. Soils under conventional tillage are normally characterized by the lowest
soil moisture values at surface and increasing with depth. The no-tillage is normally high-
er near surface then decreases tuitil one reaches the depths of high clay content, below the
18-24-inch depth. (Figs. 10 and ll.)
12

 VOLUME PERCENT MOISTURE
OTO 12 14 16 18 2O 22 24 26 28 3O 32 34 36 38 4O 42
  r; 2¤ ’Z—`j§·s'.-; ‘`-3 Li`? v Y--
6   . __>_   __-_ v_ \
Q if  \
I is  2;.. Q )
O   \ F
Z in `
` T 24 1 »
I  4
p- I
SJ 3O •..• Conv. June 27 (6
Q o-o Conv. July 3 t
36 •-·-• No-TiI,Ju‘nc 27 .. ‘
o·-·o No-TH,.1uIy 3 ,  
I Eg
42 ( ‘
48
Fig. 11. — Soil moisture distribution with depth and different methods of tillage . Soil moisture
curves for june 27, 1969 and july 3, 1969.
NO—TILLAGE SOIL TEMPERATURE
During the few days immediately after planting, soil temperatures should be above
500F as much as possible to assure a high percentage of corn seed germination. Soil
temperatures at the 2-inch depth (the usual depth for corn seed) rise during the day time
mainly owing to sunshine directly on the soil. Also, soil temperatures fall at night because
no sunshine is received and heat which was stored by the soil during the day may be carried
away at night.
A dense layer of killed grass on top of the soil contains a certain amount of air which
the sod prevents from moving. This "dead" air is an excellent insulator. One would expect
that the sod would keep some sunshine from reaching the soil, thus producing lower day time
temperatures under a killed sod cover. Also, the sod and dead air should prevent loss of heat
at night, producing higher night time temperatures under sod killed after spring growth has
begun.
These expected effects were observed during 1967, 1968 and 1969 on the University
of Kentucky Agricultural Experiment Station Farm at Lexington. Daily observations of soil
temperature at the 2-inch depth, under both a bare soil surface and sod during March, April
and May, showed daytime maximum temperatures averaging between 4. 90 and 9.90 cooler
while nighttime minimum temperatures averaged between 2. 20 and 7. 20 warmer under sod
compared with those of adjacent bare ground. All temperatures were measured under level
ground with a close—clipped bluegrass sod or under bare ground maintained in a bare condition
by hand cultivation. There were no extended periods of unusually wet nor dry weather. Field
tests in 1967 confirmed that these conditions closely approximate those found under no—tillage
and conventional tillage with similar level field exposure. Either a heavier sod cover, a
13

 heavy mulch such as one might obtain by chemically killing a large rye grass cover crop, or
a period of extremely dry weather would undoubtedly have magnified the observed effects.
After the corn seedlings reached sufficient height to provide shading between the rows,
the 1967 tests indicated no difference between temperatures measured under no-tillage and
conventional tillage conditions. `
It is well known that heavy mulches delay warming of the soil during the spring. How-
ever, in Kentucky, it appears that soil temperatures during the spring are normally high
enough that, even with the daytime lowering due to a killed sod cover, the rate of corn seed
germination is not materially decreased. Heavier mulches provide cooler conditions but,
owing to the generally moderate level of all soil temperatures in Kentucky, the rate of seed
germination does not appear to be significantly less than that under conventional tillage. This
generalization may not hold for some wet fine—textured soils where the mulch may magnify
the normally wet cool conditions in April and May. Soil temperature tests, however, have
not been made under these wet—cool soil conditions. Corn seedling emergence under no-
tillage conditions has been observed to take place in approximately the same time as under
conventional tillage conditions in a reasonably wide range of soils in Kentucky. This condition .
may not hold true in locations farther north where the sun’s rays have a lower angle of
incidence during the spring.
CONCLUSIONS
The higher moisture content in the soil surface under no-tillage cropping has significant A
implications in soil reactions that control the availability of nutrients to the plants. The
seasonal moisture difference between no-tillage and conventional extends to an approximate
depth of 24 inches. This provides a greater reservoir of soil moisture in the major plant
rooting zone.
The conservation of moisture under no-tillage is associated with soil conditions that
maintain good surface infiltration throughout the cropping season, reduction in evaporation
due to the surface mulch and the absorptive properties of the decaying roots and surface mulch.
The greater moisture storage in the soil profile under no-tillage results in more efficient
utilization of water by the plants and provides a measure of safety against droughts.
The soil moisture data reported in this paper should not be extrapolated to all soils
and all seasons. Obviously the seasonal distribution of rainfall will alter the differences, and
different soil types will have an influence on the moisture conservation under the different
cropping systems. However, other workers (5, 6) making comparisons over 4- and 5-year
periods and different soil types have consistently shown the no-tillage method to have greater
soil profile moisture over the seasons.
The killed sod cover under no-tillage contains a dead air space that serves as an
insulator. This surface mulch prevents some of the sunshine from reaching the soil and
produces lower day soil temperatures under no-tillage than under bare conventional plots.
This insulating effect also produces a slightly higher nighttime soil temperature. After the
corn seedlings reach sufficient higher to shade the ground the difference in soil temperature
between no-tillage and conventional diminishes. The differences in soil temperature are
probably not very important on most soils of Kentucky because soil temperatures are normally
high enough for good germination with or without a mulch.
14

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15
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