Snow Management P r a c t i c e s f o r T r a p p i n g Snow
i n a P r a i r i e Environment
W.
~ i c h o l a i c h u k , ' D.M.
ray,'
ti. s t e p p u h n Y 3 F.B. Dyck 3
Introduction
Since t h e l a s t Snow Management Symposium h e l d i n 1975 i n Bismarck,
North Dakota, t h e i n t e r e s t i n snow management has grown among producers i n
western Canada.
Producers have become aware t h a t e x t e n d i n g t h e c r o p p i n g
system appears t o be t h e most p r o m i s i n g approach t o s o l v i n g problems o f 1 and
degradation due t o e r o s i o n and s a l i n i t y .
To extend t h e c r o p p i n g system i n
an environmentwherewater i s l i m i t i n g , snow rnanqqement i s considered t o be a
possible a1t e r n a t i v e (de Jong and Cameron, 1980).
The f i r s t s t u d y on management of snow was r e p o r t e d b y Mathews a t . ? '
Scott i n 1940.
From a two y e a r s t u d y , he concluded t h a t y i e l d i n c r e a s e s
from snow r i d g i n g were modest (Mathews 1940).
I n t h e s e t e s t s , windrowing
increased t h e n a t u r a l accumulation of snow by 100 p e r c e n t i n t h e r i d g e s and
30 percent between them.
I n 1972, Steppuhn of t h e U n i v e r s i t y of Saskatchewan, A g r i c u l t u r a l
The authors a r e W. N i c h o l aichuk, Head, Watershed Research S e c t i o n ,
National I n s t i t u t e of Hydrology, Saskatoon, Sask. ; D. M. Gray, Chairman,
D i v i s i o n o f Hydro1 ogy, U n i v e r s i t y of Saskatchewan, Sas katoon; H. Steppuhn,
Research S c i e n t i s t ; and F. B. Dyck, Head, Engineering Section, A g r i c u l t u r e
Canada Research S t a t i o n , S w i f t C u r r e n t , Saskatchewan.
Engineering Department, r e - i n i t i a t e d a windrowing s t u d y a t v a r i o u s l o c a t i o n s
i n western Saskatchewan (Steppuhn, 1980a).
b e n e f i t s were i n c o n s i s t e n t .
The 5-year s t u d y i n d i c a t e d t h a t
D u r i n g two o u t o f t h e f i v e t e s t y e a r s p a r a l l e l
r i d g e s o f snow spaced a t 3.7 m a p a r t on o v e r - w i n t e r i n g s t u b b l e f i e l d s
enhanced t h e d e p o s i t i o n of wind-'borne snow and i n c r e a s e d s o i l m o i s t u r e
For example, i n one y e a r (1973-74),
stored.
t h e r e was a c t u a l l y a s o i l
moisture gain o f 51 mm (70 p e r c e n t ) compared t o t h e t e s t f i e l d n o t windrowed.
S i m i l a r l y , i n a s t u d y conducted by K i r k l a n d and Keys (1981) showed t h a t snow
r i d g i n g d i d n o t s i g n i f i c a n t l y i n c r e a s e t h e m o i s t u r e r e s e r v e s as compared t o
t h e check on f a l l o w and s t u b b l e .
An a l t e r n a t i v e t o snow r i d g i n g f o r snow t r a p p i n g was t h e use o f
permanent t a l l wheat grass b a r r i e r system.
T a l l wheat grass p l a n t e d i n
s i n g l e o r double rows spaced 9 t o 15 m a p a r t p e r p e n d i c u l a r t o t h e p r e v a i l i n g
winds has proved e f f e c t i v e f o r snow management i n Montana (Black & Siddoway
However, t h e b a r r i e r s do have t h e i r p r a c t i c a i 1 i m i t a t i o n s .
1976).
Spacing
o f rows t o e f f i c i e n t l y accommodate v a r i o u s c u l t u r a l o p e r a t i o n s , grass
encroachment i n t o t h e i n t e r - b a r r i e r area and t h e p o t e n t i a l f o r p l a n t disease
and i n s e c t i n f e s t a t i o n s a r e o n l y some of t h e problems t h a t can be encountered
To overcome some of t h e shortcomings o f windrowing snow and t h e use of
grass b a r r i e r s , t h e A g r i c u l t u r a l Canada Research S t a t i o n a t S w i f t Current
i n i t i a t e d a study i n t h e f a l l o f 1972 t o t r a p snow by swathing a t a l t e r n a t e
heights.
The s t u d y o f u t i l i z i n g s t a n d i n g s t u b b l e f o r snow t r a p p i n g was
expanded i n l a t e r y e a r s by an AERD c o n t r a c t w i t h t h e D i v i s i o n o f Hydrology
o f t h e U n i v e r s i t y o f Saskatchewan t o develop equipment f o r l e a v i n g a
s t r i p o f t a l l s t a n d i n g s t u b b l e t o improve t h e t r a p p i n g e f f i c i e n c y .
In
a d d i t i o n , t h e D i v i s i o n o f Hydrology expanded t h e s t u d i e s t o assess t h e
p o t e n t i a l o t t r a p p i n g snow w i t h t h e use of l e a v e s t r i p s and t a l l s t a n d i n g
stubble a t seven l o c a t i o n s i n Saskatchewan.
T h i s paper w i l l r e v i e w t h e appl i c a t i o n o f d i f f e r e n t non-competi t i ve
and c o m p e t i t i v e snow management p r a c t i c e s and equipment u s e d . r f o r ' - t r a p p i n g snow i n t h e
Canadian p r a i r i e s .
o f " t a l l stubble",
The p r a c t i c e s t o be discussed w i 11 i n c l u d e t h e management methods
"a I t e r n a t e - h e i g h t " s t u b b l e and " d e f l e c t o r " and " c l i p p e r "
s t r i p s and t h e use o f permanent grass b a r r i e r s t r i p s of t a l l s t u b b l e .
Snow Management P r a c t i ces and Snow
Cover D i s t r i b u t i o n P a t t e r n s
Snow management t o i n c r e a s e s o i l water c o n s e r v a t i o n r e q u i r e i t h a t
snow be trapped, d i s t r i b u t e d and h e l d on t h e f i e l d s u n t i l t h e c r o p i s grown.
T h i s a l s o means t h a t on m e l t i n g , t h e water s h o u l d have good o p p o r t u n i t y t o
e n t e r t h e s o i l r a t h e r t h a n be l o s t by r u n o f f .
B a r r i e r s f o r snow management
can be grouped i n t o "competi t i ve and noncompeti ti ve t y p e s , dependi ng upon
whether t h e b a r r i e r compets w i t h t h e crop f o r t h e s o i l w a t e r s u p p l y .
(a)
Noncompetitive B a r r i e r s
S t u b b l e management i s t h e most v i a b l e snow management p r a c t i c e f o r
t h e p r a i r i e s because o f t h e t y p e o f crops grown and n a t u r e o f c u l t u r a l
operations.
The most p o p u l a r methods i n c l u d e t a l l s t u b b l e , a1 t e r n a t e h e i g h t
stubble, t r a p s t r i p s and l e a v e s t r i p s .
T a l l Stubble --the
t e r m " t a l l " s t n b b l e i s used i n a " r e l a t i v e " sense
t o i n f e r t h a t t h e crop i s c u t a t t h e highest h e i g h t p o s s i b l e d u r i n g t h e
h a r v e s t i n g o p e r a t i o n t h u s l e a v i n g a f i e l d of " h i g h " s t u b b l e .
p r a c t i c e i s used wheni;the c r o p i s straight-combined.
Normally t h i s
The a c t u a l h e i g h t o f a
" t a l l " s t u b b l e i s a f u n c t i o n o f t h e crop v a r i e t y , p l a n t d e n s i t y and c r o p
height b u t usually will f a l l in the range from 30 t o 60 cm.
Alternate-Height Stubble - - t h i s p r a c t i c e involves harvesting t h e
crop t o leave bands of stubble of a l t e r n a t e height within a f i e l d (low and
high).
The w i d t h of each band i s normally t h e width of the swather.
By
adjusting the swather-height on each round of a f i e l d a s e r i e s of bands of
"low" (15-30 cm) a n d " t a l l " stubble (30-60 crn) are formed.
Trap S t r i p s - t h i s practice, a l s o referred t o as deflector o r c l i p p e r
s t r i p s (depending on t h e device used) involves leaving narrow s t r i p s of t a l l
stubble in a f i e 1 d.
Prel iminary work a t t h e Swift Current Research S t a t i o n
during 1979 indicated t r a p s t r i p s could be created r e l a t i v e l y simply using
attachments mounted on a swather during windrowing operations (Dyck e t a l .
1982). Development was continued with two Agri cul ture-Canada AERD contracts
with the Agricultural Engineering Department, University of Saskatchewan
during 1979 and 1980 (Steppuhn 1980b) and subsequently a t the Swift Current
Research Station during 1981 to the present.
Two types of deVices~ldeveloped
are:
(a) d e f l e c t o r type:
Two models of deflection were developed:
a
single V-shaped u n i t and a double triangular-shaped unit with a space
between the two.
The double d e f l e c t o r can be mounted in a diverging o r
converging mode ( F i g . 1 and 2 ) i n t o a swather.
'The sing1 e d e f l e c t o r leaves a s i n g l e V-shaped pattern as i 11ustrated
i n Figure 1.
This i s achieved by bending the s t a l k s of grain t o each s i d e
before they get t o t h e c u t t e r bar, t h u s when they are cut a longer stubble
i s l e f t as compared t o t h e s t a l k s t h a t a r e cut when standing s t r a i g h t .
The
differential length i s determined by t h e distance the s t a l k i s bent over
prior t o cutting.
A 1 i f t e r f i n g e r i s employed on each side of the d e f l e c t o r
F i g . 1.
Single deflector w i t h stubble pattern
t o ensure t h a t t h e heads g e t c u t and g e t d e p o s i t e d o n t o t h e d r a p e r ( F i g . 1).
The double d e f l e c t o r i s designed t o l e a v e two s t r i p s of t a l l s t u b b l e
s i d e by side.
B a r r i e r p o r o s i t y i s thus reduced and a more e f f e c t i v e snow
fence i s created.
barrier i s left.
h e i g h t (Table 1 ).
Mounted i n t h e d i v e r g i n g mode (Fig. 2),
an Al\-shaped
V a r i o u s w i d t h s of d e f l e c t o r can be used depending on crop
A c r o p h e i g h t of 60 cm i s about t h e minimum t h a t w i l l
l e a v e an e f f e c t i v e b a r r i e r when c u t w i t h a d e f l e c t o r - e q u i p p e d o r c l i p p e r equipped swather.
I n d e s i g n i n g a d e f l e c t o r a number of f a c t o r s a r e i m p o r t a n t .
Good
d i v i s i o n of t h e c r o p i s e s s e n t i a l and can be achieved w i t h a l o n g l e a d i n g
F i g . . 2.
edge.
Double d i v e r g i n g d e f l e c t o r w i t h s t u b b l e
pattern
A s k i on t h e f r o n t reduces t h e p o s s i b i l i t y o f d i g g i n g i n t o t h e ground
when c u t t i n g low o r when a r i d g e i s encountered.
To m a i n t a i n c r o p f l o w w h i l e
t h e s t a l k s o f g r a i n a r e " d e f l e c t e d " o r b e n t t o t h e s i d e , a moderate angle
(40'
o r l e s s ) s h o u l d be used.
Too b l u n t an a n g l e w i l l r e s u l t i n a b u l l d o z i n g
a c t i o n and t h e s t a l k s o f g r a i n w i l l bend forward,
r a t h e r t h a n t o t h e side,
and s l i p under t h e c u t t e r b a r w i t h o u t b e i n g c u t .
Smooth round edges (1 i ke a
r o d ) on t h e d e f l e c t i n g rnernber a l s o minimize t h e drag on t h e s t a l k s - a s they
Table
Crop height
1
Double d e f l e c t o r width
Barrier height
4 space "- 30 cm
5 space= 38 cm
6 space = 45 cm
are deflected t o t h e side.
The deflector should be roughly parallel t o t h e
ground when the c u t t e r bar i s a t normal cutting height.
clipper type:
(b)
Engineering Department.
Two models were designed by the Agricultural
The f i r s t mounted externally on the reel arm of the
right-hand end of a self-propelled swather.
0.4
111
The c l i p p e r consisted of a
cutter bar, a reel and a narrow draper t o d e l i v e r the cut material
onto the upper portion of the larger draper of the swather.
The clipper
reel and cutter bar a r e a t constant distance b u t t h e c u t t e r bar height can be
adjusted by raising o r lowering the main reel.
upper 15 t o 20 cm of the grain s t a l k .
I t i s normally s e t t o cut t h e
Depending on the crop height, about
30 t o 60 cm d i f f e r e n t i a l in stubble height can be achieved.
The second model mounted inboard on the right-hand end of the c u t t e r
bar and required extensive modifications t o the swather reel.
I t essential l y
achieved the same r e s u l t b u t the heads of grain were mixed into the longer
material whereas t h e f i r s t model delivered the cut material onto the top of
the windrow.
The stubble pattern of both clippers is of block design 0.4 m wide
(Fig. 3 ) .
Care m u s t be taken i n driving t h e swather t o avoid cutting off
the barrier on the next round.
The t h i r d model developed a t the Agriculture Canada Research Station
Fig. 3
Cl i p p e r s t u b b l e p a t t e r n .
a t Swift Current consists o f a t r a i l i n g c l i p p e r .
b a r on the swather i s blanked o f f by a guard.
A s e c t i o n o f the c u t t e r
T r a i l i n g behind the s w a t h e r
i s a c l i p p e r attachment t h a t c u t s t h e upper o p e r a t i n g p o r t i o n o f t h e g r a i n
s t a l k and d e p o s i t s t h a t p o r t i o n on t o p o f the swath made by the s w a t h e r .
The t r a i l i n g model makes i t a d a p t a b l e t o most makes of swathers.
Leave S t r i p s - In t h i s p r a c t i c e , 30 t o 40-cm wide s t r i p s of c r o p ,
spaced 1 , 2 o r 3 swather-combine widths a p a r t a r e l e f t unharvested t o a c t a s
b a r r i e r s t o t r a p snow.
4.6 t o 7.6 m.
The w i d t h o f a s w a t h e r u s u a l l y i s i n the r a n g e from
W i t h a 30-cm wide s t r i p p l a c e d on a 15-m s p a c i n g , a p p r o x i m a t e l y
2% o f t h e a r e a of a f i e l d is l e f t unharvested.
A p a r t i c u l a r advantage i n c u t t i n g a f i e l d t o l e a v e s t u b b l e a t
d i f f e r e n t h e i g h t s i s t h a t t h e v e g e t a t i v e s u r f a c e formed i s aerodynamical l y
rougher t h a n t h a t of a uniform s t u b b l e ; c o n s e q u e n t l y , i t s snow t r a p p i n g
e f f i c i e n c y i s higher.
'The p r a c t i c e would be f a v o u r e d where crop c o n d i t i o n s ,
p r i n c i p a l l y d e n s i t y and h e i g h t , a r e i n s u f f i c i e n t t o provide a " t a l l " d e n s e
s t u b b l e and on highly-exposed t o p o g r a p h i c f a c e t s , e . g . ,
the tops of ridges
and knoll s.
Figures 4 and 5 a r e t y p i c a l snowcover accumulation p a t t e r n s found i n
f i e l d s a t Eston and Saskatoon h a r v e s t e d w i t h "a1 t e r n a t e - h e i g h t " and " t r a p
s t r i p " practices.
The d a t a i n F i g u r e 4 were o b t a i n e d i n March o f 1 9 8 3 a t a
s i t e where snowcover, wind and o t h e r c o n d i t i o n s f a v o u r e d accumulation and i t
Fig. 4
Snowcover accumulation p a t t e r n on l.
a f i e l d c u t with "alternate-height"
s t u b b l e management p r a c t i c e ,
Eston, Saskatchewan, 1983
Fig. 5
Snowcover accumulation p a t t e r n s on
a f i e l d cut with "trap s t r i p "
s t u b b l e management p r a c t i ce a t
Sas katoon , Saskatchewan , 1983.
W
width o f the deflector s t r i p ;
S
d i s t a n c e between s t r i p s
can be observed t h a t t h e snowcover f i l l e d t h e v e g e t a t i o n .
The average
3
density o f t h e snow i n t h e low s t u b b l e was 207 kg/m ; t h e h i g h e r d e n s i t y i n
the t a l l s t u b b l e due t o g r e a t e r p a c k i n g by wind.
T a k i n g an average snowcover
depth i n t h e low s t u b b l e o f 20 cm, and 40 cm i n t h e h i g h s t u b b l e , t h e
d i f f e r e n c e i n snow w a t e r e q u i v a l e n t on t h e two s t r i p s would be
57.8 mrn
which r e p r e s e n t s an average i n c r e a s e o v e r t h e f i e l d a t t r i b u t a b l e t o t h e t a l l
stubble o f
28.9 mm.
The d a t a i n F i g . 5 were c o l l e c t e d i n February, 1983
and show l a r g e r accumulations i n a f i e l d w i t h d e f l e c t o r s t r i p s t h a n i n an
adjacent f i e l d o f " t a l l " s t u b b l e .
I n t h e f i g u r e n o t e t h e change i n t h e
accumulation p a t t e r n i n t h e s t r i p s caused by r e d l ~ c i n gb o t h ' t h e w i d t h and
spacing o f t h e s t r i p s b y a f a c t o r of about two.
The accumulation on t h e
wide spacing e x h i b i t s an u n d u l a t i n g p a t t e r n as a r e s u l t o f scour o r e r o s i o n
o f snow from between t h e s t r i p s .
Conversely, on t h e a r e a w i t h t h e s t r i p s
placed on t h e narrow spacing t h e depth of snowcover i s more uniform and
deeper; t h e average increase in depth being approximately 5 cm.
Further
work i s needed t o define t h e i n t e r a c t i o n between snowcover accumulation, t h e
physical properties (spacings, d e n s i t y , h e i g h t ) of s t r i p s and upwind f e t c h
conditions in order t o e s t a b l i s h design c r i t e r i a f o r t h i s stubble management
practice.
(b)
Competitive Barriers
The Tall Wheat Grass b a r r i e r s concept developed i n northern Montana
(Black & Siddoway 1976) and l a t e r s t u d i e d a t Swift Current has been found
t o be e f f e c t i v e f o r trapping snow.
B a r r i e r s c o n s i s t of t a l l wheat g r a s s
planted i n single o r double rows spaced 9 m t o 15 rn a p a r t .
The grass b a r r i e r
offers a greater potential f o r trapping more snow than t h e non-competitive
types.
This i s mainly a t t r i b u t e d t o t h e f a c t t h a t t h e t a l l wheatgrass
provides a barrier t h a t i s a meter i n height o r more.
The accumulation p a t t e r n s found i n grass b a r r i e r s tends t o be a
function of wind t r a n s p o r t conditions and amount of snow available.
Basically, deposition of snow o r i g i n a t e s in t h e leeward s i d e of t h e b a r r i e r
perpendicular t o the p r e v a i l i n g winds.
Observations i n d i c a t e t h a t t h e
uniformity of snow accumulation i s highly dependent on wind d i r e c t i o n and
t r a n s p o r t conditions.
Snow Management Practices and Snow Cover Accurr~ula t i on
(a)
Tall Stubble
Studies on the use of t a l l stubble f o r trapping snow was conducted by
the Division of Hydrology a t Saskatoon and P o r t Reeve.
This p r a c t i c e lends
i t s e l f t o producers who s t r a i g h t corr~binet h e i r crops.
Based on four years of data, the amount of moisture stored i n t a l l
stubble appears t o be l i n e a r l y related t o t h e depth of snow (Table 2 ) .
Table
2
Stubble height, snow accumulation
a n d water equivalent i n normal and
" t a l l " stubble
Based on average stubble height d i f f e r e n t i a l of 6 cm between
conventional stubble height a n d t a l l stubble height s u i t a b l e f o r s t r a i g h t
combining, the net increase i n snow water equivalent available f o r s o i l
recharge was 1.6 cm.
Consequently the amount of moisture t h a t can be gained
by u t i l i z i n g " t a l l " stubble i s limited by t h e height of stubble.
.Any
additional gain i n snow water equivalent can only be derived 5y increasing
t h e snow density of t h e trapped snow.
(b)
Deflector Trap System
Studies of the d e f l e c t o r t r a p system were carried o u t a t seven
locations in Saskatchewan by the Division of Hydro1 ogy and by Agriculture
Canad? a t S w i f t C u r r e n t .
The d e f l e c t o r system has p r o v e n t o be t h e most p o p u l a r f o r m
o f snoN management because of t h e simp1 i c i t y o f t h e d e f l e c t o r d e v i c e t h a t can be
r e a d i l y adapted t o most swathers.
As e v i d e n c e d by T a b l e 3, t h e average g a i n
i n snow water e q u i v a l e n t i s o n l y 1.1 cm.
for
'
However, i n e x a m i n i n g t h e p o t e n t i a l
t r a p p i n g a d d i t i o n a l w a t e r can be as g r e a t as 5.6 cm w h i c h i s e q u i v a l e n t
t o the amount o f w a t e r t h a t i s conserved by summerfallowing ( S t a p l e and
Lehane).
Table 3
Snow i c c u m u l a t i on and w a t e r
equivalent using a deflector t r a p
s t r i p system.
Various drawbacks e x i s t i n u t i l i z i n g t h e d e f l e c t o r syste~rl. G r a i n
h e i g h t must be s u f f i c i e n t i n o r d e r t o e f f e c t i v e l y c r e a t e a t r a p s t r i p o f t a l l
stubble t h a t w o u l d be e f f e c t i v e i n c a u s i n g d e p o s i t i o n o f snow and t h e r e b y
increasing t h e snow w a t e r e q u i v a l e n t .
P o s i t i o n i n g t h e d e v i c e on t h e s w a t h e r
i s another m a j o r p r o b l e m f a c i n g p r o d u c e r s .
Location i s c r i t i c a l t o prevent
"tramping down" b y t h e wheels of a t r a c t o r and combine d u r i n g h a r v e s t
operations.
Coup1 ed w i t h necessary adjustments t o accommodate g r a i n h e i g h t
and p o t e n t i a l h a r v e s t i n g l o s s e s makes some producers w a r y o f u s i n g t h i s
device.
(c)
C l i p p e r T r a p System
The c l i p p e r t r a p system i s a much more s o p h i s t i c a t e d s y s t e m t h a t i s
s t i l l i n t h e development stages.
The o b j e c t i v e s i n d e s i g n i n g a c l i p p e r
attachment were as f o l l o w s :
1.
t h e attachment must l e a v e a s t r i p of s t u b b l e of maximum h e i g h t ;
2.
a l l seed heads'must be c u t and conveyed t o t h e swath;
3.
a l l heads must be p l a c e d i n t h e swath i n such a manner t h a t
combining losses a r e n o t increased;
4.
t h e attachment m ~ ~ be
s t adjustable t o s u i t crop height, preferably
from t h e d r i v e r 5 seat;
5.
t h e attachment must n o t i n t e r f e r e w i t h t h e ease and q u i l i t y o f
swathing;
6.
the attachment should be s u i t e d t o f i t any swather.
Since a l l o f t h e design r e q u i r e m e n t s have n o t been f u l f i l l e d t o date,
most s t u d i e s have been confined t o c r e a t i n g a b a r r i e r o f t a l l s t u b b l e
u t i l i z i n g a s e l f - p r o p e l l e d swather.
Data on snow trapped by t h e c l i p p e r system a r e p r e s e n t e d i n Table 4.
Compared t o t h e d e f l e c t o r system, t h e p o t e n t i a l appears t o be g r e a t e r .
This
may be a t t r i b u t e d t o t h e p o r o s i t y o f - t h e " c l i p p e r - t y p e " b a r r i e r t h a t r e s u l t s
i n a h i g h e r degree of t u r b u l e n c e and d e p o s i t i o n .
Table 4
Snow accumulation and water e q u i v a l e n t u s i n g a c l i p p e r t r a p system
On t h e average, t h e snow w a t e r equivalleht of t h e c l i p p e r t r a p system
i s n e a r l y doubled.
The maximum d i f f e r e n t i a l i n snow w a t e r e q u i v a l e n t
between t h e c l i p p e r and c o n t r o l was 8 cm compared t o a maxinium o f 5.6 cm
observed f o r t h e d e ' f l e c t o r
system.
(d)
"Leave" System
The " l e a v e t r a p " system which s i m p l y i s l e a v i n g a s t r i p o f t a l l
s t a n d i n g unharvested g r a i n has s i m i l a r p o t e n t i a l f o r t r a p p i n g snow as t h e
c l i p p e r system.
On t h e average, t h e snow w a t e r e q u i v a l e n t w i t h t h e t r a p
system i s double t h a t of t h e c o n t r o l ( T a b l e 5).
The maximum d i f f e r e n t i a l
o f a d d i t i o n a l w a t e r t r a p p e d observed i n t h e f o u r y e a r s o f s t u d y was 8.9 cm
which i s somewhat h i g h e r t h a n t h e c l i p p e r ,system.
Table 5
Snow a c c u m u l a t i o n and w a t e r
equivalent using a leave t r a p
sys tern
However, t h e main drawbacks of t h i s system o f snow management i s due
t o t h e l o s s o f g r a i n h a r v e s t e d ( e s t i m a t e d a t 5%) and c o n t a m i n a t i o n o f t h e
f i e l d f o r r e c r o p p i n g due t o v o l u n t e e r growth.
In addition, there i s a
p o t e n t i a l hazard t h a t heads o f g r a i n may cause sta'l k breakage d u r i n g h i g h
winds i n t h e f a l l and w i n t e r , t h e r e b y r e d u c i n g t h e e f f e c t i v e n e s s of t h e
barrier.
(e)
Swathing a t A1 t e r n a t e H e i g h t s
Swathing a t a l t e r n a t e h e i g h t s i s a f o r m o f snow management t h a t has
been i n v e s t i g a t e d f o r a p e r i o d of 13 y e a r s a t t h e S w i f t C u r r e n t Research
Station.
Treatments c o n s i s t e d o f a1 t e r n a t e l y s w a t h i n g t h e wheat c r o p a t
two d i f f e r e n t h e i g h t s u s i n g a s e l f - p r o p e l l e d s w a t h e r .
on t h e c r o p s t a n d c o n d i t i o n ( T a b l e 5 ) .
The h e i g h t s a r e dependent
The c o n t r o l c o n s i s t e d of wheat t h a t
Table 6
Snowfall , snow accumulation and
snow w a t e r e q u i v a l e n t on t h e
u n i f o r m and nonuniform s t u b b l e
system o f snow management ( 1 972-85)
(cm) a t S w i f t C u r r e n t , Sask.
was swathed a t a u n i f o r m h e i g h t .
The average d e p t h o f snow trapped by non-uniform s t u b b l e was 4 cm
o r 22% more than on t h e u n i f o r m stubble.
A d d i t i o n a l water i n t h e i n c r e a s e d
amount o f snow t r a p p e d was 1.4 cm o r 23% g r e a t e r i n d i c a t i n g an a p p r o x i m a t e l y
1i n e a r r e l a t i o n s h i p between depth and m o i s t u r e e q u i v a l e n t .
(f)
Competitive Grass B a r r i e r s
Use o f grass b a r r i e r s f o r snow management has been s t u d i e d a t
A g r i c u l t u r e Canada Research S t a t i o n , S w i f t C u r r e n t , s i n c e 1979.
The grass
b a r r i e r system o f f e r s t h e p o t e n t i a l f o r t r a p p i n g more snow than t h e
noncompetitive types.
T h i s i s mainly a t t ~ i b u t e dt o t h e f a c t t h a t t h e t a l l
wheatgrass provides a b a r r i e r t h a t i s a meter i n h e i g h t o r more.
Ddt.a
susgest t h a t t h e b a r r i e r system t r a p s a p p r o x i m a t e l y t w i c e as much snow
compared t o the u n i f o r m s t u b b l e wheat (Table 7 ) .
Not only d i d t h e b a r r i e r system t r a p o f f e r an o p p o r t u n i t y t o t r a p
more snow, t h e n e t i n c r e a s e i n water s t o r e d was 73% g r e a t e r t h a n t h e
c o n t r o l (Table 8 ) .
and Siddoway 1976.
'
R e s u l t s t o date are s i m i l a r t o those r e p o r t e d by B l a c k
Table 7
S n o w f a l l accumul a t i on and
accumulation w i t h a grass b a r r i e r
system o f snow management a t S w i f t
C u r r e n t , Sas k.
Table 8
O v e r w i n t e r s o i 1 w a t e r s t o r a g e and
e f f i c i e n c y f r o m t h e b a r r i e r system
o f snow management a t S w i f t
C u r r e n t , Sas k.
Summary
For t h e P r a i r i e s , t h e r e i s ample evidence t o s u p p o r t t h e s t r o n g
a s s o c i a t i o n between t h e h e i g h t of a v e g e t a t i o n b a r r i e r and t h e d e p t h o f snow
cover under adequate f e t c h and w i n d c o n d i t i o n s .
Based on l i m i t e d d a t a , t h e
grass b a r r i e r s f o l l o w e d by c l i p p e r and " l e a v e s t r i p " o f f e r t h e p o t e n t i a l t o
t r a p t h e most snow under p r a i r i e c o n d i t i o n s .
However, f o r p r a c t i c a l reasons
c i t e d e a r l i e r i n t h e t e x t , t h e d e f l e c t o r system a t t h i s p o i n t i n t i m e i s t h e
most p r a c t i c a l a l t e r n a t i v e .
As t h e c l i p p e r a t t a c h m e n t i s improved and can
be mass produced a t a r e a s o n a b l e c o s t , i t may become t h e b e s t a l t e r n a t i v e
t o snow t r a p p i n g .
However, t h e assurr~ptiont h a t t h e amount o f snow m e l t i n f i l t r a t i o n can
be r e l a t e d t o snow c o v e r d e p t h i s tenuous as addressed b y o t h e r speakers o f
t h i s snow management workshop.
As a r e s u l t , t h e a d o p t i o n o f t h i s t e c h n o l o g y
w i l l remain l i m i t e d unless producers a r e w i l l i n g t o accept t h e r i s k t h a t
b e n e f i t s from snow management may n o t be achieved due t o problems a s s o c i a t e d
w i t h snowmel t i n f i l t r a t i o n , amount o f s n o w f a l l received, e t c .
F u r t h e r r e s e a r c h i s r e q u i r e d t o improve t h e equipment f o r snow
t r a p p i n g u s i n g t h e t r a p s t r i p systems.
Equipment i s r e q u i r e d t o accommodate
lodged g r a i n and s h o r t g r a i n h e i g h t ( p a r t i c u l a r l y i n y e a r s when snow
management i s r e q u i r e d ) .
References
Black, A.L.
and Siddoway, F.H.
1976.
D r y l a n d c r o p p i n g sequences w i t h i n a
J . Soi 1 and Water Conserv. 31 : 101-1 05.
t a l l wheatgrass b a r r i e r system.
de Jong, E. and Cameron, D.R.
1980.
Water use e f f i c i e n c y by a g r i c u l t u r e
under d r y l a n d c o n d i t i o n s . I n Proceedings , Canadian Wheat Board
Symposi urn, Oct. 29-30,
Dyck, F.B.,
Nicholaichuk, W.,
Saskatoon, Sask.
Steppuhn, H. and Zeorb, G.C.
attachments f o r snow management.
In Proceedings,
1982.
Swather
S o i l s and Crops
Workshop, Saskatoon, Saskatchewan.
K i r k l and, K. J. and Keys, C. H.
1981 . The e f f e c t o f snow, t r a p p i n g and
cropping sequence on m o i s t u r e c o n s e r v a t i o n and u t i l i z a t i o n i n West
Central Saskatchewan.
Mathews, G.D.
1940.
Can. J . P l a n t S c i . 61 : 241-246.
Snow u t i l i z a t i o n i n p r a i r i e a g r i c u l t u r e .
CDA pub1 .
No. 696.
Staple, W.J. and Lehane, J.J.
and Wenhardt, A.
1960.
moisture f r o m f a l l and w i n t e r p r e c i p i t a t i o n .
Conservation o f s o i l
Can. J. S o i l S c i .
40: 80-88.
Steppl~hn, H.W.
1980a.
No. 80-407.
Windrow-ing snow t o i n c r e a s e snow w a t e r .
Paper
CSAE Annual Meeting, August 3-7, 1980, Edmonton,
A1 b e r t a .
Steppuhn, H.W.
1980b.
Swather Attachment f o r Snow T r a p p i n g .
AERD P r o j e c t
Report, C o n t r a c t No. OSZ79-00103, S w i f t C u r r e n t , Sas k.
Steppuhn, H.W.
1980c.
F i n a l Report AERD C o n t r a c t No. 07SZ.01843-9-0916
Swather A t t a c h m n t s f o r Snow Management.
50
-
n
E
U
0"
z
4
40
X
-
l-
s
S O
30-
l-4
a w
wx
n
3
W
ul3
l-
U)
-
20
om
zm
lo
-
-SNOW
-
STUBBLE HEIGHT
DISTANCE
F i g u r e 4.
DEPTH
Crn>
Snowcover accumulation p a t t e r n on a f i e l d c u t
w i t h " a l t e r n a t e - h e i g h t " s t u b b l e management p r a c t i c e ,
Eston, Sask.,
1983.
-
SNOW D E P T H
LLW
W I
0
i -
STRIPS
W
0
-
1.B
I
0
25
1
m
I
1
1
DISTANCE
Figure 5.
1
1
50
1
1
1
1
1
1
75
1
1
100
<m>
Snowcover accumulation patterns on a f i e l d c u t with
" t r a p s t r i p " s t u b b l e management p r a c t i c e a t Saskatoon ,
Sask., 1983.
W = width of t h e d e f l e c t o r s t r i p ;
S = d i s t a n c e between s t r i p s .
T a b l e 2.
S t u b b l e h e i g h t , snow a c c u m u l a t i o n and w a t e r e q u i v a l e n t i n normal
and " t a l l " s t u b b l e .
Control
"Tall
" Stubble
Year
Stubble
height
Snow
depth
Water
equivalent
Stubble
height
Snow
depth
as katoon
1980
30.3
24.9
6.6
4.7.9
29 - 0
7.9
P o r t Reeve
1982
--
15.4
2.6
--
34.0
8.6
1984
--
22 .O
7.1
--
22 - 5
Location
Mean
20.8
5 .0
27.0
Water
equivalent
5.2
-
6.6
Table 3.
Snow Accumulation and Water E q u i v a l e n t Using a d e f l e c t o r t r a p
s t r i p system
Control
Water
Equivalent
Deflector
Year
Depth
S w i f t Current
1982
17
6.3
34.7
9.7
1983
16.7
3.2
19.1
4.4
1984
16.4
4.1
13.8
5.3
Sas katoon
Bad Lake (N-S)
(E-W)
Es t o n
Aberdeen
F l axcombe
R i chlea
Mean
Depth
Water
Equivalent
Location
T a b l e 4.
Snow accumulation and w a t e r e q u i v a l e n t u s i n g a c l i p p e r t r a p
sys tern
Control
Location
Year
Swift Current
1982
1983
1984
1985
S a s katoon
-Kernan
-Kernan
(N)
-Kernan
-Kernan
(N)
(S)
MEAN
1979
(S)
1980
Depth
Water
Equivalent
Cl i p p e r
Depth
Water
Equivalent
-
Table 5.
Snow accumulation and w a t e r e q u i v a l e n t u s i n g a . l e a v e t r a p
sys tern.
Control
Water
Equivalent
Leave S t r i p
Year
Depth
Sas katoon
1978
12.8
3.3
36.8
12.2
1979
23.3
21.6
7-0
6.7
47.9
36.4
16.5
11.6
1983
21 .I
3.7
21.9
3.9
5.4
36.4
10.3
-Kernan
.-Kernan
(N)
(S)
Depth
Water
Equivalent
L o c a t i on
P o r t Reeve
Mean
22.4
-
Table 6.
Snowfall, snow accumulation and snow w a t e r e q u i v a l e n t on the uniform and
nonuniform s t u b b l e system of snow management (1972-85) (cm) a t S w i f t
Current, Sas k .
Uniform S t u b b l e
Year
Stubble
Snowfall Height
Avg .
Snow
Depth
Equi v .
Moisture
Nonuniform S t u b b l e
Stubble
Trapped Height
%
1972-73
1973-74
,
1974-75
1975-76
1976-77
1977-78
1978-79
1979-80
1980-81
1981-82
1982-83
1983-84
1984-85
Average
0 Snow survey was n o t conducted p r i o r t o s p r i n g melt.
Avg .
Snow
Depth
Equiv.
Moisture
%
Trapped
Table 7.
Snowfall accumulation and w a t e r e q u i v a l e n t w i t h a g r a s s b a r r i e r
system of snow management a t S w i f t C u r r e n t , Sask.
% of snowfall
Con t r o 1
Within b a r r i e r
Year
Snowfall
Depth
Water
equivalent
1979-80
1980-81
6.0
9.6
9.7
2:7
--
1981-82
1982-83
1984-85
10.0
9.0
5-0
10.5
47.4
31 - 0
30.2
31 - 4
Mean
8.4
29.9
1983-84
Depth
trapped
Water
equivalent
Within
barrier
1.6
--
Control
--
7.1
--
--
45
--
12 -9
21.8
6.6
129
66
6.2
6.3
10.4
17.6
14.6
8.3
3.5
3.1
2.5
69
39
62
24
7.7
31.8
3.5
126
99
94
-- Snow survey was not conducted p r i o r t o s p r i n g me1 t .
26
43
T a b l e 8.
O v e r w i n t e r s o i l w a t e r s t o r a g e and e f f i c i e n c y f r o m t h e b a r r i e r s y s t e m
o f snow rnanaglment a t S w i f t C u r r e n t , Sask.
Barrier
Year
Overwinter
p r e c i it a t i o n
Pcm)
1979-80
7.7
1980-81
11.4
1981 -82
11 . O
1982-83
11.3
1983-84
7.2
1984-85
11.4
Mean
10.0
Soi 1 water
intake
(cm)
Intake
efficiency
(%I
Nonbarrier
Soi 1 w a t e r
intake
(cmI
1ntake
efficiency
( %I