spot east 2018 results · summary of spot n trials (2016-2018) spot site year variety n treatments...
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SPot East 2018 Results
Nitrogen work over three years
Marc Allison & Mark Stalham
Hypothesis: does N application drive yield?
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Yiel
d (
40
-90
mm
@ 2
3.3
% D
M, t
/ha)
Nitrogen applied to crop (kg N/ha)
Data from 556 processing crops 2010-2016
Mean ware yield at 23.3 % DM = 50.0 t/ha
Mean N application rate = 201 kg N/ha
Survey data suggest otherwise
British Survey of Fertilizer Practice & AHDB
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1970 1980 1990 2000 2010 2020
Ave
rage
N a
pp
licat
ion
(kg
N/h
a)
Mai
ncr
op
yie
ld (
t/h
a)
Maincrop yield
Average N application
Summary of SPot N trials (2016-2018)
SPot site Year Variety N treatments
Summary of N
effects on yield
Yields >40 mm
(t/ha) Tuber DM (%)
East 2016 R Burbank Split N, All N in
seedbed (both 260)
No effect 68.2, 68.3 22.0, 22.1
2017 Brooke Split N, All N in
seedbed, Placed N
(all 220), 160, 180,
220, 160+30
No effect of rate
or timing. Placed
lower
61.0, 61.1,
55.7, 61.2,
59.2, 61.0, 62.3
24.5, 24.8, 25.0,
24.3, 24.3, 24.7,
24.3
2018 Estima 180, 210, 240, 270 No effect 54.8, 56.9,
56.6, 55.1
18.9, 18.8, 18.4,
18.5
North 2018 M Piper 120, 150, 180,
150+30
No effect 49.7, 48.1,
49.3, 50.7
23.6, 23.4, 23.2,
23.4
South West 2017 Electra 90, 120, 150 No effect 58.7, 61.7, 61.3 17.1, 16.3, 16.4
2018 Electra 0, 30, 60, 90, 120 No effect 72.0, 61.2,
72.4, 73.4, 72.3
16.4, 15.7, 15.6,
15.8, 16.4
Scotland 2017 M Piper 177, 147, Liquid,
Injection
Injection lower 54.3, 51.2,
54.5, 49.8
19.2, 19.4, 18.5,
18.4
2018 M Piper 176, 147, 120,
Placed
TBA TBA TBA
Setting the N rates for SPot East 2018
Step Process Factors Outcome
1 Calculate soil nitrogen supply
(SNS)
Cereal stubble, sand soil in a low
rainfall area
SNS Index = 0
(soil will supply <60 kg N/ha)
2 Identify determinacy group Estima Variety group = 1 (determinate)
3 Calculate season length 24 May (emergence) to end August
(defoliation)
Season length = 100 days
4 Calculate initial N requirement of
crop
237 kg N/ha
5 Calculate supply from organic
manures
Compost November 2016 0 kg N/ha (but soil OM is 2.7 %)
6 Fertilizer required 240 kg N/ha
Can we use soil tests to guide N fertilizer recommendations?
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Op
tim
um
N a
pp
licat
ion
rat
e (k
g N
/ha)
Soil mineral N measured in the spring (kg N/ha)
Neeteson (1990, 0-60 cm)
Johnson & Chambers (1998, 0-60 cm)
Neeteson (1984, 0-30 cm)
Allison (2003, 0-90 cm)
Relationship between tuber N uptake and tuber dry matter yield
y = 15.25 (± 0.075)xR² = 64.2P < 0.001
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Tub
er N
up
take
(kg
N/h
a)
Tuber DM yield (t/ha)
Big N uptake = big yield?
y = 0.0882x + 30.208R² = 0.2628
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0 100 200 300 400 500Maximum recorded total N uptake (kg N/ha)
Yiel
d (
40
-90
mm
@ 2
3.3
% D
M, t
/ha)
Data from 402 processing crops 2010-2016 where N uptake was measured
Mean ware yield at 23.3 % DM = 49.6 t/ha
Mean total N uptake = 220 kg N/ha
Effect of N on yield formationRusset Burbank, CUF 2008
Nitrogen
applied
(kg N/ha)
Total
N uptake
(kg N/ha)
Integrated
GC
(% days)
Radiation
absorbed
(TJ/ha)
Total
DM
(t/ha)
RUE
(t/TJ)
Harvest
index
(%)
Total FW
yield
(t/ha)
0 142 7843 12.78 14.22 1.12 93 56.7
125 197 8622 13.75 16.59 1.21 87 64.7
250 225 9071 14.16 17.49 1.24 87 69.1
375 308 10262 15.26 18.88 1.24 87 77.8
S.E. 25.1 318.2 0.381 1.275 0.071 2.5 3.78
Sampled 29 September
Relationship between N uptake by tubers and fertilizer N application
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Tub
er N
up
take
(kg
N/h
a)
Nitrogen applied (kg N/ha)
y = 108.4 (± 8.38) + 0.317 (± 0.041)xR² = 4.0P < 0.001
What factors affect the amount of N taken up by the crop?
?
N application N
uptake
Tuber Yield 4 %
96 %
PCN
Water
(deficient/excess)
Soil compaction
Environment
(radiation/temperature)
Pathology
?
Soil Nitrogen Supply
Effect of compaction and irrigation on nitrogen uptake. Maris Piper CUF 2006
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1-May 1-Jun 2-Jul 2-Aug 2-Sep 3-Oct
Tota
l N u
pta
ke (
kg N
/ha/
day
)
Compacted-Irrigated
Compacted-Rainfed
Uncompacted-Irrigated
Uncompacted-Rainfed
Approx. time of T.I.
What do we mean by N use efficiency?
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Nit
roge
n r
emo
ved
in t
ub
ers
(kg
N/h
a)
Nitrogen applied as fertilizer (kg N/ha)
Fertilizer
N applied (kg
N/ha)
N in tubers
(kg N/ha)
Increase in N
uptake
(kg N/ha)
Efficiency of
N use
(%)
0 94 - -
80 164 70 88
160 212 48 60
240 239 26 33
320 243 4 5
Fertilizer N not
in tubers
(kg N/ha)
-
10
32
54
76
Effect of irrigation, N application and variety on tuber yield. CUF Reference Crop 2006-2017
Estima Cara
Rain-fed Irrigated Rain-fed Irrigated
kg
N/hat/ha
kg
N/hat/ha
kg
N/hat/ha
kg
N/hat/ha
Mean146
± 27.6
43.6
± 4.77
193
± 19.5
65.4
± 3.42
87
± 21.8
58.0
± 3.53
87
± 22.5
70.1
± 4.74
Irrigation increased optimum N application rate by 47 kg N/ha in Estima and
0 kg N/ha in Cara
Data from Firman
020406080100
12-May02-Jun 23-Jun 14-Jul 04-Aug25-Aug
Gro
un
d c
ove
r (%
)
Std Irrig, Split N
Std Irrig, seedbed N
Freq Irrig, Split N
Freq Irrig, seedbed N
O-water Irrig, Split N
SPot Farm East 2016Nitrogen x Water Comparison
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24-Jun 08-Jul 22-Jul 05-Aug 19-Aug
SPA
D m
ete
r re
adin
g
160
180
220
160+Topup
SPAD Meter: measuring leaf chlorophyll content for predictions of N deficiency
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24-Jun 08-Jul 22-Jul 05-Aug 19-Aug
SPA
D m
ete
r re
adin
g
Standard
Over-water
Soil NO3 sensors(Tony Miller, JIC + Agrii)
Soil mineral N from soil coresLower N in deepest profile in over-watered
20
Effect of rainfall and irrigation strategy on estimates of N leaching at SPot Farm East
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Nit
roge
n le
ach
ed b
elo
w 6
0m
cm
(kg
N/h
a)
Drainage below 60 cm (mm)
Over watered and 260 kg N/ha in seedbed
Up to 55 days after emergence and assuming no N uptake by the crop, potential leaching losses were c. 53 kg N/ha
No evidence that reduced N increases bruising
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180 N 210 N 240 N 270 N
SPot E 2018 Estima
Incidence (%)
Bruise depth (mm)
020406080
SPot N 2018 Maris Piper
Incidence (%)
Bruise depth (mm)
Isn’t it about what is sold rather than yield digs?SPot Scotland 2017 Packout (Albert Bartlett)
Trial 1 2 3 4
Treatment Planting
Top dress
Liquid
Standard
(177 N)
Standard
Ridge inject
(175 N)
Standard
No top dress
(147 N)
Standard
Standard
(176 N)
Crop harvested No. boxes 23 24 24 22
Graded product Tonnes 14.24 14.70 15.88 14.12
Packout % 64.6 62.9 67.6 64.9
Yield packed t/ha 37.5 37.8 40.9 36.1
Financial summary of SPot N trials to date
Commercial split N All N in seedbed Financial Placed/injected Financial
61.2 t/ha +0.1 t/ha +£20/ha -4.9 t/ha -£980/ha
Commercial rate Optimal rate N saving Financial
57.2 t/ha +0.8 t/ha -53 kg/ha +£197/ha
Summary
• Used RB209 to calculate N requirement for crop and site and mostly found 30-60 kg N/ha lower than commercial rate being used on surrounding crop
• Experiments and strip trials showed no evidence of loss of yield from these lower rates
• Placed or injected N tended to produce lower yields than broadcast
• No evidence that much N leached out of the rooting profile during the growth period on heavily irrigated sandy soils, but canopies were paler and shorter-lived where over-watering took place
• Decreased N did not result in increased bruising
• Decreased N resulted in better skinset
Acknowledgements
•NIAB CUF would like to thank Andrew Francis and Emma
Kelcher and their team at Elveden for all their help and
support in conducting experiments and trials during 2018-
2018
• AHDB staff involved in the SPot East programme including:
Jenny Bashford, Graham Bannister and Teresa Meadows
•Nick Winmill of Agrii and Tony Miller of John Innes Centre for
supplying soil nitrate-measuring probes
• Peter Raatjes of RMA for installing Adcon soil water
monitoring probes
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