What's the Buzz about Radishes and Brassicas? Nitrogen...
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What's the Buzz about Radishes and Brassicas? Nitrogen Dynamics Laura L. Van Eerd University of Guelph Ridgetown Campus
Transcript of What's the Buzz about Radishes and Brassicas? Nitrogen...
What's the Buzz about Radishes and Brassicas?
Nitrogen Dynamics
Laura L. Van EerdUniversity of Guelph Ridgetown Campus
Cover Crop Growth
December 2006 May 2007Oat OSR+Rye No Cover Rye OSR+Rye No Cover Rye Oat
Bothwell – Cover Crops Plant N
*For each date, bars labeled with the different letters are significantly different.
Bothwell – Cover Crop Soil N
*For each date, bars labeled with the different letters are significantly different.
Bothwell – Cover Crop PAN
*For each date, bars labeled with the different letters are significantly different.
Bothwell – Cover Crop Summary
• Cover crops were effective at conserving plant available N over the fall and into the spring compared to the no cover control
• All covers were equally as effective in the spring
Is there a N credit?
Bothwell – Sweet Corn PAN
*For each date, bars labeled with the different letters are significantly different.
Plant available N (PAN) = soil mineral N + sweet corn plant N
Ridgetown – Sweet Corn PAN
*For each date, bars labeled with the different letters are significantly different.
Plant available N (PAN) = soil mineral N + sweet corn plant N
Discussion
• Cover crops may be effective at conserving N over the cover crop growing season
• Little evidence that this translated into increased PAN for the sweet corn crop
• These cover crops do not increase or decrease N fertilizer applications to the sweet corn
-40-20
020406080
100
Red Clover-Fall Control
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020406080
100Red Clover-Spring Control
1
2
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020406080
100No Cover
LSD=27.99LSD=28.99
ActualNitrate
ActualAmmonium
RelativeNitrate
RelativeAmmonium
-40-20
020406080
100
-40-20
020406080
100
Red Clover-Fall Control
-40-20
020406080
100
-40-20
020406080
100Red Clover-Spring Control
1
2
-40-20
020406080
100
-40-20
020406080
100No Cover
LSD=27.99LSD=28.99
LSD=27.99LSD=28.99
ActualNitrate
ActualAmmonium
RelativeNitrate
RelativeAmmonium
ActualNitrate
ActualAmmonium
RelativeNitrate
RelativeAmmonium
-40-20
020406080
100Perennial Ryegrass
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100
Oilseed Radish
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100
16/9/03 6/10/03 23/10/0314/11/03 12/4/04 26/4/04 10/5/04 26/5/04 9/6/04 21/6/04 19/7/04 1/9/04 29/11/040 20
010
0 0 200
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100 0 20
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Oats
-40-20
020406080
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-40-20
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100Perennial Ryegrass
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Oilseed Radish
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16/9/03 6/10/03 23/10/0314/11/03 12/4/04 26/4/04 10/5/04 26/5/04 9/6/04 21/6/04 19/7/04 1/9/04 29/11/0416/9/0316/9/03 6/10/036/10/03 23/10/0323/10/0314/11/0314/11/03 12/4/0412/4/04 26/4/0426/4/04 10/5/0410/5/04 26/5/0426/5/04 9/6/049/6/04 21/6/0421/6/04 19/7/0419/7/04 1/9/041/9/04 29/11/0429/11/040 20
010
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Oats
Impact of cover crops on PSNT soil nitrates (data from Dr. Bill Deen U of Guelph)
If there is no N credit, then why bother?
Soybeans Fall rye OSR+rye No cover Oats
0
500
1,000
1,500
2,000
2,500
Oats + Nfertilizer
Rye + Nfertilizer
Oilseedradish + rye +
N fertilizer
No covercrop + Nfertilizer
Oats + 0N Oilseedradish + rye +
0N
No covercrop + 0N
Rye + 0N
cover crop
prof
it m
argi
ns ($
/ha)
Economics Bothwell-2007
a
b b bbc
cd
dee
0
1,000
2,000
3,000
4,000
5,000
6,000
7,000
Oilseedradish +
N fertilizer
Rye + Nfertilizer
Oilseedradish +
0N
Oilseedradish +rye + Nfertilizer
Oilseedradish +rye + 0N
No covercrop + Nfertilizer
Oats + Nfertilizer
Rye + 0N No covercrop + 0N
Oats + 0N
cover crop
prof
it m
argi
ns ($
/ha)
Economics Ridgetown-2008
a a a ababc
abc bccd
cdd
Economics Ridgetown-2009
0
1000
2000
3000
4000
Rye + Nfertil izer
Oilseedradish +
Nfertil izer
Oilseedradish +
0N
Oilseedradish +rye + N
fertil izer
Oilseedradish +rye + 0N
Oats + Nferti l izer
Rye + 0N No covercrop + Nfertil izer
Oats +0N
No covercrop +
0N
cover crop
prof
it m
argi
ns $
/ha
aa aa a a ab ab
b
ab
Summary on N in Brassicas
• Trap N• No N credit• Economics may not be a limiting factor
Laura Van [email protected]
Cover Crops After Cucumbers
Planting date: August 4
Photo taken: October 21
Soil Sample Date
july sept oct
Soil
Nitr
ate
(ppm
)
0
5
10
15
20
25
30
35no cover cropoatsrye + OSR
Cover Crops: Soil N
Cover crops trap N in the fall
Date (2006)
May Jul Sep Nov Jan
Soil
min
eral
N (k
g N
/ha)
10
20
30
40
50
60
70
80No coverOatsRyeOSR+rye
Cover crops – cucumbers
Early planted -1st week in AugustLate planted -1st week in September
Early v. Late Planting Dates
Figure 1. Quantity of nitrogen in cover crop aboveground tissues and recoverable residue collected in the fall 2008 and 2009. Different letters indicate a statistically significant difference.
Cover crops – cucumbers
0
1000
2000
3000
No covercrop
WITH N
Oats 0N OSR 0N Peas 0N Vetch 0N No Cover0N
Rye 0N Ryebiomassremoved
0Ncover crops
inco
me
$/ha
a
ab ab
bc bc
d
cd cd
Cucumber Yield
Cover Crop Cucumber Harvest 2009Marketable yield (Mg ha-1) Marketable yield income ($ ha-1)
No Cover 7.17 cd 2235 cdeNo Cover + N 12.25 a 3405 aOSR 10.10 ab 2933 abOats 9.19 bc 2988 abPeas 9.89 abc 2569 bcRye 6.13 d 1871 eRye Removed 7.35 bcd 1975 deVetch 9.32 bc 2474 bcd
Table 2.2 Cucumber yield (Mg ha-1) and yield income ($ ha-1)* in 2009. Cover crop treatments with different letters indicate a statistically significant difference.
Early v. Late Planting Dates
0
20
40
60
80
100
120
Plan
t N U
ptak
e (k
g N
ha-1
)
Cover Crop Type
ab
c
ab
c
a
bc
a
a
a
bc
OSR Oats Peas Rye Vetch
LateEarly
Figure 2. Quantity of nitrogen in cover crop aboveground tissues and recoverable residue collected in April, 251 and 291 DAP. Different letters indicate a statistically significant difference.
Yields
Bothwell Ridgetown
Total yield Marketable
yieldTotal yield
Marketableyield
N treatment
No cover
Oat OSR+rye Rye
---------------t ha-1 ---------------- t ha-1 t ha-1 t ha-1
0N 6.5 a 11.4 bc 11.4 bcd 6.7 ab 5.4 a 40.0 a 22.4
140N 12.2 cd 15.2 d 14.0 cd 13.7 cd 9.5 b 45.9 b 19.5
P value 0.038 0.001 0.001 0.310
Bothwell – Cover Crop Growth
December 2006 May 2007Oat OSR+Rye No Cover Rye OSR+Rye No Cover Rye Oat
Ridgetown - Cover Crop Biomass
*For each date, bars labeled with the different letters are significantly different.
Bothwell - Cover Crop Biomass
*For each date, bars labeled with the different letters are significantly different.
Cover Crop Growth
August 2007 October 2007No Cover Rye OSR+Rye Oat OSR OSR Oat OSR+Rye No Cover Rye
Ridgetown – Cover Crop Plant N
*For each date, bars labeled with the different letters are significantly different.
Ridgetown – Cover Crop Soil N
*For each date, bars labeled with the different letters are significantly different.
Ridgetown – Cover Crop PAN
*For each date, bars labeled with the different letters are significantly different.
Ridgetown – Cover Crop Summary
• Cover crops were effective at conserving plant available N over the fall and into the spring compared to the no cover control
• Oat was most effective in the fall due to high plant N content
• All covers were equally as effective in the spring• Cover crops generally did not affect PAN in the
fall or spring compared to the no cover • Cover crops were less effective at preventing N
loss than at Bothwell, possibly due to differences in soil type and precipitation
N Credit?
• Need to compare to NO cover crop control
• Show fall N uptake and lower soil N but does this result in a N credit?
Cover Crops Plant N
O O O O O O
Cov
er c
rop
plan
t N u
ptak
e (lb
N/a
c)
0
50
100
150
200
0N 100N 200N 0N 100N 200N Oats Rye with Oilseed Radish
Cover Crop
