Processes and BMPs Controlling P Loss During Snowmelt: Snow and ...

Processes and BMPs Controlling
P Loss During Snowmelt:
Snow and Rain
are not the Same
Don Flaten, University of Manitoba
Great Lakes P Forum/SERA-17 Annual Meeting
July 29, 2009 - Windsor, Ontario
Photo: David Lobb

Assigned Questions
1. Do we know the seasonality and
magnitude of P losses in different
temperate and continental cold
climates?
2. How do frozen soils and hydrology
affect the relative proportions of
dissolved and particulate P during
spring freshet?
3. Do we sufficiently know the
interactions between field
management and winter/spring
melt P losses to develop more
effective BMPs?

First, a few caveats ...
some of my biases

Lake Winnipeg - the
6th Great Lake

Manitoba landscapes are flatter and the weather is
dryer and colder than in the Great Lakes region
• Flat – low risk of water erosion
• Dry – < 500 mm precipitation/year
• Cold – 80-90% of runoff as snowmelt, over thawing
vegetative residues and frozen soil

1. Do we know the seasonality and
magnitude of P losses in different
temperate and continental cold
climates?
2. How do frozen soils and hydrology
affect the relative proportions of
dissolved and particulate P during
spring freshet?

Rainfall Runoff System for P Loss
Rainfall:
Infiltration
and
Percolation
Soil Erosion:
(Particulate P)
Release of Soluble P
to Runoff
Surface Runoff:
(Dissolved P)
Total Surface
P Loss:
Particulate +
Dissolved P
Near- and In-stream
Processes
P Leaching and
Subsurface Runoff
Effective Depth of
Interaction (< 5 cm)
(Adapted from Wood 1998)

Snowmelt Runoff System for P Loss:
Snow Accumulation Phase
No "raindrop"
splash
Frozen Soil?
Dead or dormant
vegetation in fields and
buffers

Snowmelt Runoff System for P Loss:
Snowmelt Phase
Snowmelt:
Little
Infiltration or
Percolation
Release of soluble P
to runoff from soil
and veg. residues
Soil Erosion:
(Particulate P)
Little P Leaching
and Subsurface
Runoff
Surface Runoff:
(Dissolved P)
Shallow Effective Depth
of Interaction (< 2.5 cm)
Total Surface
P Loss:
Particulate +
Dissolved P
Near- and In-stream
Processes
Frozen Soil?

Snow accumulation is highly variable ...
usually greater in and near streams
Photo: David Lobb

Clearing accumulations of snow and ice
from drainage channels during snowmelt
April 2009 near Selkirk, Manitoba

Accumulations of snow block and divert
"natural" drainage
Photos: David Lobb

Monitoring vegetated buffers ...
bring snowshoes
Photo: S. Sheppard

Water quality sampling in vegetated buffers
during snowmelt
Photo: Stephen Carlyle, Gimli, Manitoba, March-April 2009

Effective depth of interaction between runoff and
soil is shallow and temporally/spatially variable
Photos: David Lobb

Significant amounts of
soil erosion may still
occur during snowmelt
... especially when soil
is highly saturated,
partially thawed, and
bare

What are the functions of in and near stream
processes during snowmelt?
Photo: David Lobb

Snowmelt runoff in Minnesota
Photos: Wall, Dave. How does the MN P index relate to MPCA policies?
http://www.mnpi.umn.edu/downloadfiles/Pindexandfeedlotrules.pdf

Snowmelt Runoff in Ohio
March 1, 2007
February 26, 2007
Photos: Wilson, Rick. 2007. Phosphorus: A Summary of Pertinent Research.
http://www.epa.state.oh.us/dsw/lakeerie/ptaskforce/PTaskRW091007.pdf

Snowmelt runoff is relatively slow and complex
Streamflow During Rainfall Runoff Events
Streamflow During Snowmelt Runoff Events
Glozier et al. 2006. Water quality characteristics and trends in a small
agricultural watershed: South Tobacco Creek, Manitoba, 1992-2001.

Diurnal pattern of snowmelt runoff in
Sweden (Ulen 2003)

Proportion of P in the dissolved form in snowmelt
runoff in streams is relatively high and stable
Ratio TDP/TP
1.0
0.8
0.6
0.4
0.2
0.0
y = -0.0399x + 0.4512
R 2 = 0.3526
y = -0.0095x + 0.6121
R 2 = 0.0661
0 2 4 6 8 10 12 14 16 18 20 22
Flow, m 3 /s
Snowmelt
Summer
Adapted from Glozier et al. 2006. Water quality characteristics and trends
in a small agricultural watershed: South Tobacco Creek, Manitoba, 1992-
2001.

Proportion of dissolved P in edge of field compared
to nearby stream is especially high in dissolved P and
low in particulate P
1
0.8
Snowmelt
Summer
Ratio TDP/TP
0.6
0.4
0.2
0
Edge of Field
Stream
Elliott et al. 2007 (unpublished)

Predominance of dissolved P is often
greatest in early portion of snowmelt runoff
The proportion of the
soluble reactive
phosphorus (SRP) of
the total phosphorus
concentration for
snowmelt runoff in
Finland (Rekolainan
et al. 1989).

Addressing snowmelt P loss in P indexes
and models: Minnesota P Index
Assumes that 18% of applied P and crop residue P is lost per inch of runoff

3. Do we sufficiently know the
interactions between field management
and winter/spring melt P losses to
develop more effective BMPs?

What BMP tools do we expect farmers to use?
• Source BMPs
• P balance, rate application, STP
• Placement, timing of manure and
synthetic fertilizer application
• Conservation tillage?
• Transport BMPs
• Conservation tillage?
• Vegetated buffers
• Cover crops
• Constructed wetlands and small
reservoirs

At high levels of STP, STP is strongly related to total P
concentrations in runoff
10
9
0 to 15 cm
0 to 2.5 cm
b
8
0 to 15 cm
TP FWMC (mg L -1 )
7
6
5
4
3
2
0 to 2.5 cm
TP = 0.014 * STP (0-15 cm) + 0.16
r 2 = 0.88
TP = 0.013 * STP (0-2.5 cm) + 0.039
r 2 = 0.87
1
0
0 100 200 300 400 500 600
Typical Prairie
STP value
STP (mg kg -1 )
Little, J.L, Nolan, S.C, Casson, J.P. and Olson, B.M. 2007. Relationships between soil and
runoff phosphorus in small Alberta watersheds. J. Envir. Qual. (2007). Snowmelt > 90% of
runoff, DP = 55 % of TP, Modified Kelowna STP extraction method.

At low levels of STP, STP is not related to total P
concentrations in runoff from Alberta watersheds
1.8
FWMC TP (mg/L)
1.6
1.4
1.2
1
0.8
0.6
0.4
0.2
native rangeland
cultivated cropland
Native prairie in Minnesota yielded average
of 0.5 mg/L TP in runoff where 80% of runoff
was snowmelt ... rainfall runoff averaged 0.7
mg/L (Timmons & Holt 1977)
spring 2003
summer 2003
spring 2004
summer 2004
spring 2005
summer 2005
0
0 20 40 60 80 100
Typical Prairie
STP value
Modified Kelowna P (mg/kg)
Adapted from Little, J.L, Nolan, S.C, Casson, J.P. and Olson, B.M. 2007. Relationships
between soil and runoff phosphorus in small Alberta watersheds. J. Envir. Qual. (2007).
Snowmelt > 90% of runoff, DP = 55 % of TP, Modified Kelowna STP extraction method.

Time and method of nutrient application
• Manure or fertilizer on frozen soil or snow is bad
agronomically and environmentally … especially
where snowmelt forms a large proportion of
runoff (eg. Srinivisan et al. 2006, Klausner 1976,
Young & Mutchler 1976)
• Injected, banded, or incorporated applications
are recommended, especially for fall application

Conventional vs. conservation tillage in
snowmelt systems - South Tobacco
Creek WEBs project in Manitoba

Twin watershed study - average annual P loading from
zero till were greater than losses from conventional till ...
and dissolved P losses dominated in both
P loss (lb P 2 O 5 /ac/yr)
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
Dissolved P
Particulate P
Zero till management
started in fall 1996
CT “ZT” CT ZT
1993-1996 2004-2007
(Tiessen et al. unpublished)

ANCOVA showed that conservation tillage
increased average annual total P export by 12%
0.40
calibration period
Linear (calibration period)
treatment period
Linear (treatment period)
Treatment watershed
(ZT_EW) (kg/ha)
0.35
0.30
0.25
0.20
0.15
0.10
0.05
y = 1.12x + 0.02
R 2 = 0.70*
1:1 line
y = 0.72x + 0.03
R 2 = 0.62*
0.00
0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35
Control watershed
(CT_WW) (kg/ha)

Effect of zero tillage vs. conventional tillage
varied with season and water quality parameter
Runoff
Export
Parameter
Rainfall Runoff
Ranking*
Means**
ZT CT
Runoff (m 3 /ha/yr) ZT < CT 80 173
Sediment (kg/ha/yr) ZT < CT 11 25
PP (kg/ha/yr) ZT < CT 0.019 0.034
TDP (kg/ha/yr) ns 0.052 0.046
TP (kg/ha/yr) ns 0.071 0.080
* Differences in rankings determined by Kruskal-Wallace non-parametric test
** Means are simple arithmetic means for the post-treatment period (2004-2007)
Tiessen et al. 2009 (unpublished)

Effect of zero tillage vs. conventional tillage
varied with season and water quality parameter
Runoff
Export
Parameter
Rainfall Runoff
Ranking*
Means**
ZT CT
Snowmelt Runoff
Ranking
Means
ZT CT
Runoff (m 3 /ha/yr) ZT < CT 80 173 ns 727 730
Sediment (kg/ha/yr) ZT < CT 11 25 ZT < CT 10 65
PP (kg/ha/yr) ZT < CT 0.019 0.034 ns 0.085 0.096
TDP (kg/ha/yr) ns 0.052 0.046 ZT > CT 0.493 0.212
TP (kg/ha/yr) ns 0.071 0.080 ZT > CT 0.578 0.308
* Differences in rankings determined by Kruskal-Wallace non-parametric test
** Means are simple arithmetic means for the post-treatment period (2004-2007)
Tiessen et al. 2009 (unpublished)

Other experiences with conservation tillage
in snowmelt runoff systems
Ridge tillage in
Minnesota
decreased
sediment loss
relative to chisel,
but increased TP
loss ... runoff P
losses for all tillage
systems were
dominated by DP
(avg. 75%)
Hansen et al. 2000

Vegetated buffer strips not as effective as
expected in SE Manitoba (Sheppard et al. 2006)
• DP = 74% of TP, snowmelt dominant runoff
• VBS reduced runoff [TP] in 50% of cases,
increased P in 18%, had no effect in 32%
• overall average only 4% reduction in runoff [TP]
Photo: Steve Sheppard

Other experiences with vegetated buffers
and perennial forages in snowmelt runoff
• In Finland, no reduction in P loss from perennial
forage vs. cultivated field in dissolved and colloidal
P dominated snowmelt runoff (Ulen 2003)
• In Pennsylvania runoff simulator studies:
– without freezing, cover crop decreased runoff
[TP] from manured soil by 76%
– after freezing & thawing, cover crop increased
[TP] in runoff from manured soil by 762%
– water extractability of P increased with number
of freeze-thaw cycles (Bechmann et al. 2006)

Other experiences with vegetated buffers
and perennial forages in snowmelt runoff
• In Wisconsin, P loss from alfalfa increased with
freeze-thaw, as well as natural or chemical
dessication in simulated runoff ... but not in
natural runoff (Roberson et al. 2007)
• In Vermont, vegetated buffers intercepted dairy
barnyard runoff P well during growing season,
but not in fall-winter or snowmelt periods
(Schellinger and Clausen 1992)
• In Finland, 32 P labelling indicated only 16%
retention of P in vegetated buffers during
snowmelt, with almost all retention by soil
particles (Vaananen et al. 2006)

Small reservoirs reduce sediment and
nutrient loading in snowmelt systems
eg. small reservoir in South
Tobacco Creek WEBS
project reduced loads of:
– sediment (77%)
– TN (15%), TDN (14%)
– TP (12%), TDP (10%)
– mechanisms?

Summary and Conclusions
• Processes controlling P loss in snowmelt runoff
are not well known … partly because of extreme
spatial and temporal variability during snowmelt
runoff events
Photo: David Lobb

Summary and Conclusions, cont’d.
• BMPs for controlling P loss in snowmelt runoff
are not well developed ... partly because the high
proportion of dissolved and colloidal P is
difficult to intercept, especially when soil is
frozen and plants are dead or dormant
– Source BMPs
» P balance, soil test P are important,
but vegetative residues and "fresh
frozen" manure are very important
sources during snowmelt
– Transport BMPs
» if erosion is not the main cause of P
loss, erosion control measures will
do little to reduce P loss

Investing in Additional Research ...
http://umanitoba.ca/cgi-bin/human_resources/jobs/view.pl?posting_id=82345

Summary and Conclusions, cont’d.
• In the interim, focus farmers' efforts and public
policy on the most obvious P source/loading
issues … eg. balance P application with removal
and avoid winter application of nutrients

Acknowledgements
• Kevin Tiessen, David Lobb, Darshani
Kumaragamage, Clay Sawka, Esther Salvano, U of M
• Jane Elliott, Nancy Glozier, Environment Canada
• Steve Sheppard, Ecomatters
• Jim Yarotski, AAFC-PFRA and WEBs manager
• Bill Turner, Deerwood Soil & Water Mgmt. Ass'n.
• Sheilah Nolan, Alberta Agric., Food and Rural Dev.