ptiperspectives f nfrom norway - ksla.se˜gaard.pdf · trp = 1.63 ptrp = 1.63 p--al + 89.6al + 89.6...
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Today’s knowledgeToday’s knowledgeand potential for future research P ti f N-Perspectives from Norway
Anne Falk ØgaardAnne Falk ØgaardMarianne Bechmann
Svein SkøienBioforsk Jord og miljø
Eutrophic lake in a complex agricultural landscape
- How do we reduce P loads to the lake most efficiently?y
P loss processes
Source Transport Sink
........................................
..
After Sharpley et al. 2001
Soil erosion – the main focus in Norwayy
Maps of erosion risk -derived from soil maps
S il i ff t f d d ilSoil erosion – effect of reduced soiltillage
Results from lysimeter experiments
Effect of red ced tillage in a t mn on soil lossEffect of reduced tillage in autumn on soil loss
Middel årlig jordtap 1992-2000 for 5 forsøksfelter
500
600
700
Høstpløying
Ikke pløying
Clay soils on all sites
Slope 10-13%
300
400
500
Knowledge gaps:- Effect of reduced tillage on
0
100
200
gareas with low erosion risk
- Effect of reduced tillage on subsurface runoff0
Bjørnebekk Askim Hellerud Øsaker Syverud
Jordtap kg/daa
subsurface runoff
Helge Lundekvam
Tillage winter wheatPlot 2:Harrowing before seedinggSS-kons: 1110 mg/l
Plot 3:Di t d illiDirect drillingSS-kons: 5 mg/l
Pl t 42 3 4 Plot 4:Ploughing before seedingSS-kons: 5820 mg/l
2 3 4
Surface runoff 16.09.04 - 05.10.04
ErosionErosion risk at different tillagerisk at different tillage
Autumn ploughing 1,00
Autumn harrowing 0,50
Spring ploughing (No autumn tillage) 0,14
Grass 0,05
From plot scale to catchment scale
Mørdre catchment (JOVA catchment): • Increased area with no autumn tillage from 1990 to 2009 Increased area with no autumn tillage from 1990 to 2009
• But still increased particle and phosphorus concentration in the stream
• Climate change increased runoff
500300SS TP Avrenning
300350400450500
200
250
300
g (m
m)
TP (g
/daa
)100150200250
50
100
150
Avre
nnin
g
S (k
g/da
a), T
050
0
91/9
292
/93
93/9
494
/95
95/9
696
/97
97/9
898
/99
99/0
000
/01
01/0
202
/03
03/0
404
/05
05/0
606
/07
07/0
808
/09
SS
C ti itConnectivity
Sedimentation of eroded soilbefore it reaches watercourses?
Distance to watercourses and landscape shapesp p
Improved soil structure reduced erosion riskImproved soil structure reduced erosion risk
Average yearly soil and P loss in surface runoff
Soil aggregate
Suspendedsolids
Phosphorus
Average yearly soil and P loss in surface runoff
aggregatestability
solidskg/ha kg/ha
AskimSlope 13%Clay 29%
Low 2990 3,4
SyverudSyverudSlope 13%Clay 23%
High 131 0,39
H. Lundekvam
Erosion in streams
Algal availability of P in subsoil? Algal availability of P in subsoil?
Soil and P losses also through tile drainsSoil and P losses also through tile drains
Kværnø og Bechmann (2010)
P fertilization and soil P status P fertilization and soil P status
1200
800
1000/L
)P-AL 24
400
600
800
otal
P (µ
g
200
400To
P-AL 7
00 100 200 300 400
Suspended solids (mg/L)
Marianne Bechmann
p ( g )
Particle bound P not always particle bound
12
Clay soil, Ås
12
Sandy soil, Råde
6
8
10
12
(mg/10
0g)
P‐AL 3,5
P‐AL 4,9
P‐AL 8,7
P‐AL 13 6
8
10
12
(mg/10
0 g)
P‐AL 6,3
P‐AL 9,2
P‐AL 24
P‐AL 38
0
2
4
0 200 400 600 800
CaCl2‐P
0
2
4
0 200 400 600 800
CaCl2‐P
0 200 400 600 800
solution:soil
0 200 400 600 800
solution:soil
Critical soil test P value for P loss?
20
Silty clay loam
10
15
aCl2
(mg
P/kg
)
0
5
0 10 20 30 40
P-C
a
Tore Krogstad
P-AL (mg/100g)
Particle bound P available for algae?Particle bound P available for algae?
Biotests (Krogstad & Løvstad, 1991):( g , )
• 20-70 % of total P in cultivated soilpotential available for blue green algae; potential available for blue-green algae; dependent of the part of inorganic P
• Organic P was not readily available for algae
Chemical test (Krogstad & Løvstad, 1991):
• Total Reactive P (TRP) in soil suspensionsotal eact ve ( ) so l suspe s o s≈ P available to blue-green algae
Algal available P related to P-AL
Algal available P (TRP) as a function of P-AL
600
g)
400
500
TRP
(mg/
kg
200
300
0 50 100 150 200 250 3000
100TRP = 1.63 PTRP = 1.63 P--AL + 89.6AL + 89.6
RR22 = 0.73= 0.73
P-AL (mg/kg)
Tore Krogstad
P distribution on particle-size fractionsp
• Particles <20 µm would stay suspended long enough to be a t ti l f P t lpotential source of P to algae (Huettl et al. 1979)
• Increasing P concentration with decreasing particle size
Sandy soil Clay soilP‐AL 23,5 P‐AL 28mg P/kg mg P/kgmg P/kg mg P/kg
Whole soil 800 1600
< 20 µm 4400 1800< 20 µm 4400 1800
< 2 µm 7100 3800
Rikard Pedersen 2008
• A large part of excess P fertilization is found in the clayfraction (Øgaard 1996)
Reduced P fertilization in the catchment of western Vansjø
kg P/ha g
2004 2007 2008 2009
Average for 75 % of the fields 22 11 5,8 4,4 of the fields
Effects of reduced P fertilization on P runoff?
TP/SS relationship in streams
Small constructed wetlands for P retention
Effect of constructed wetlands
Braskerud (2001):• Retention of soil particles: • Retention of soil particles:
45 -75%
• Retention of total P: 21 – 44%
• Retention of dissolved P: Low
Tore KrogstadTore Krogstad
Maintenance of constructed wetlands importantMaintenance of constructed wetlands important
mm
)
n (%
)
renn
ing
(m
g re
tens
jon
AvÅrli
g
TP SS Avrenning (mm)
Filtralite P® filter at the end of constructed wetlands
Fil li P (0 5 4 ) E d d l i h li• Filtralite P (0,5-4 mm): Expanded clay aggregates with lime
• Cost of Filtralite P: 65-90 € per m3
WetlandWetland
Filter
Outlet
P retention in the filter -ft t bli h tone year after establishment
350
200
250
300P/l
50
100
150TP µg
Before filter
After filter
0
50
Data from E. Hougsrud 2009
But: Only 0.2 l/s through the filter
R i d h t i ti f Required characteristics for filters for agricultural runoff
• High hydraulic conductivity
• High adsorption capacity and short reaction time
• Flocculation of clay particles
G d b ff Grassed buffer zones
• Where are grassed buffer zones efficient?
- topography- soil type
soil tillage- soil tillage
• If the grass is not cut; release f di l d P d i of dissolved P during
winter/spring
Grassed buffer zones
100100 Grorudnson
e
8090
100
Mørdre8090
100
Mørdre
geta
sjon
506070
S506070
Snet i
veg
20304050 Sum m e r
W inte r
20304050 Sum m e r
W inte r
SS fj
ern
01020
01020
TP o
g S
TP -5m
TP -10m
S S -5m
SS -10 m
SS -5m
TP -5 m
TP -5m
TP -10m
S S -5m
SS -10 m
SS -5m
TP -5 m N. Syversen%
Release of P from different plant species after winter frost
Ongoing research:
18-42% av total P released last winter, d d ldepending on plant species
Application of manure
Injection techniques for li ti i fl manure application – influence
on risk for P losses?
Identify high-risk areas – Calculator for P-indexhttp://webgis.no/pindeks
P runoff from forests?P runoff from forests?
Thank you for the attention!