SPot Farm East Results Irrigation and nitrogen
Mark Stalham & Marc Allison
Trials conducted by NIAB CUF • N * Irrigation (sandy loam, 80 % S, 13 % C)
• N (260 kg) • Standard Split N • All N in seedbed
• Irrigation • Standard (15 mm @ 15 mm SMD) • Frequent (2 x 8 mm rather than 15 mm dose) • Over-water (25 mm @ 15 mm SMD)
• Irrigation start date for processing crops • Standard 15 mm @ 15 mm SMD from TI • Delayed start (1 week after TI)
• Scab control for packing crops (sand, 14 varieties) • Standard 10 mm SMD in bed from TI for 4 weeks, 15 mm
application • Half-frequency 20 mm SMD in bed, 25 mm application
• Sulphur (sponsored by CUPGRA)
N * Irrig: soil moisture deficits
0
1
2
3
4
5
6
0
10
20
30
40
50
60
13-May 03-Jun 24-Jun 15-Jul 05-Aug 26-Aug
Dai
ly w
ater
use
(m
m)
SMD
/Irr
igat
ion
/Dra
inag
e (m
m)
Standard Irrigation
SMD
Limiting
Scab
Irrig
Drain
PotETp
ActETp
N * Irrig: soil moisture deficits
0
1
2
3
4
5
6
0
10
20
30
40
50
60
13-May 03-Jun 24-Jun 15-Jul 05-Aug 26-Aug
Dai
ly w
ater
use
(m
m)
SMD
/Irr
igat
ion
/Dra
inag
e (m
m)
Frequent Irrigation
SMD
Limiting
Scab
Irrig
Drain
PotETp
ActETp
N * Irrig: soil moisture deficits
0
1
2
3
4
5
6
0
10
20
30
40
50
60
13-May 03-Jun 24-Jun 15-Jul 05-Aug 26-Aug
Dai
ly w
ater
use
(m
m)
SMD
/Irr
igat
ion
/Dra
inag
e (m
m)
Over Water
SMD
Limiting
Scab
Irrig
Drain
PotETp
ActETp
Irrig timing: soil moisture deficits
0
1
2
3
4
5
6
0
10
20
30
40
50
60
13-May 03-Jun 24-Jun 15-Jul 05-Aug
Dai
ly w
ater
use
(m
m)
SMD
/Irr
igat
ion
/Dra
inag
e (m
m)
Delayed Start
SMD
Limiting
Scab
Irrig
Drain
PotETp
ActETp
Best practice schedule: Rules: 1. Have to irrigate 3 days ahead of limiting SMD trigger to complete field 2. No knowledge of future rainfall 3. Have long-term ET as prediction
0
1
2
3
4
5
6
0
10
20
30
40
50
60
13-May 03-Jun 24-Jun 15-Jul 05-Aug 26-AugD
aily
wat
er u
se (
mm
)
SMD
/Irr
igat
ion
/Dra
inag
e (m
m)
SPot East Best Practice Irrigation
SMD
Limiting
Scab
Irrig
Drain
PotETp
ActETp
Comparisons: Standard, Best Practice, Optimised
Irrigation (mm)
Drainage (mm)
Water use (mm)
Efficiency† (%)
Modelled yield (t/ha)
Standard 160 96 258 97.8 65.4
Best Practice 105 41 251 95.3 63.7
Optimised 165 79 259 98.3 65.7
†Efficiency in meeting water requirement of canopy and ET demand
www.niab.com/NIAB_CUF_Irrigation_Scheduling
Agrii Soil Water Sensor Data Standard Over water
Aquaspy Soil Water Sensor Data
30
40
50
60
70
01-Jun 29-Jun 27-Jul 24-Aug 21-Sep
Re
lati
ve w
ate
r co
nte
nt
(%)
Standard
Moisture 10
Moisture 20
Moisture 30
Moisture 40
Moisture 50
Moisture 60
30
40
50
60
70
01-Jun 29-Jun 27-Jul 24-Aug 21-Sep
Re
lati
ve w
ate
r co
nte
nt
(%)
Over-water
Moisture 10
Moisture 20
Moisture 30
Moisture 40
Moisture 50
Moisture 60
Standard irrigation
Standard irrigation practice finished with the soil moisture mostly depleted
Depletion was at 20-60cm by the end of the season
Standard irrigation
Irrigation events only penetrating to ~20cm
Root activity at 60cm. Soil moisture at 30-60cm was depleted at the end of the season.
Rapid soil moisture depletion in top 60cm
Over irrigation
Over irrigation finished with greater soil moisture compared to the standard practice
Moderate depletion in 40-60cm by end of the season. Top 30cm still wet.
Over irrigation
Rapid soil moisture depletion in top 40cm
Irrigation events generally penetrating to 60cm
Drainage events recorded by Theta Probe Over Water recorded rapid wetting at every irrigation. Nothing in Standard except on 1 August but model also showed this.
Wetting across bed
Infiltration across bed after 2 hours: Standard irrigation, 18 mm, 26 July
Infiltration across bed after 2 hours: Over-water irrigation, 27 mm, 1 August
Infiltration: 17 mm 27 mm
N * Irrig: ground covers
0
20
40
60
80
100
12-May 02-Jun 23-Jun 14-Jul 04-Aug 25-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 O-water Irrig, seedbed N
Irrig timing: ground covers
0
20
40
60
80
100
12-May 02-Jun 23-Jun 14-Jul 04-Aug 25-Aug
Gro
un
d c
ove
r (%
)
Standard Delayed-start
N * Irrig: yield (irrigation means) Irrig
N
Stems
(000/ha)
Tubers >10 mm (000/ha)
Tubers <40 mm (000/ha)
Yield >40 mm
(t/ha)
>90 mm length
(%)
DM (%)
DM yield (t/ha)
Std 76 (± 7.0)
405 (± 34.5)
89 (± 19.9)
68.7 (± 4.62)
94 (± 1.4)
22.3 (± 0.41)
15.8 (± 1.29)
Freq 64 (± 5.5)
319 (± 41.6)
37 (± 11.9)
70.8 (± 5.57)
92 (± 3.1)
22.3 (± 0.41)
16.1 (± 1.42)
O-water 76 (± 15.6)
426 (± 102.0)
90 (± 51.5)
67.4 (± 5.52)
91 (± 6.4)
21.5 (± 0.81)
14.5 (± 1.87)
Irrig Timing: yield Irrig
Stems
(000/ha)
Tubers >10 mm (000/ha)
Tubers <40 mm (000/ha)
Yield >40 mm
(t/ha)
>90 mm length
(%)
DM (%)
DM yield (t/ha)
Std 82 (± 9.9)
385 (± 46.3)
67 (± 19.2)
70.9 (± 1.79)
93 (± 3.4)
22.3 (± 1.56)
16.2 (± 1.56)
Delayed start 86 (± 4.2)
397 (± 13.8)
67 (± 5.7)
75.5 (± 2.23)
89 (± 0.4)
22.8 (± 0.86)
17.2 (± 0.77)
N * Irrig: quality (irrigation means)
Irrig
Greens
(%)
Cracks
(%)
Dolls (%)
Brown centre
(%)
Hollow heart
(%)
Fry colour (USDA)
Std 0 (± 1.0)
5 (± 4.5)
3 (± 2.8)
15 (± 4.5)
8 (± 13.3)
n/a
Freq 2 (± 3.2)
3 (± 1.8)
3 (± 4.6)
15 (± 6.3)
5 (± 7.7)
n/a
O-water 0 (± 0.0)
5 (± 2.0)
5 (± 3.5)
18 (± 8.8)
9 (± 10.7)
n/a
Std 0 (± 0.0)
2 (± 1.2)
2 (± 1.2)
13 (± 5.8)
8 (± 14.4)
n/a
Delayed start 0 (± 0.6)
1 (± 0.7)
0 (± 0.0)
17 (± 15.3)
3 (± 5.8)
n/a
N * Irrig: quality: worst dolling/cracking in OW
N * Irrig: quality: worst BC/HH in frequent
Summary
• No effect of irrigation regime (rate or timing) on ground cover development or duration
• No effect of irrigation regime on yield or quality
• Twice frequency irrigation: no effect
• Delayed start: no effect
• Over watering did not advance canopy senescence or increase internal defects or misshapes but did decrease [DM]
Common scab
Maximum SMD (mm) for common scab control in different varietal scheduling groups (AHDB R448)
Group 1. Susceptible 2. Intermediate 3. Resistant
Soil texture
Varieties Maris Piper(1)
Maris Peer (5)
Charlotte (4)
Desiree (4)
Estima (6)
Exquisa
Flair
King Edward (7)
Marabel†
Melody (7)
Nectar (6)
Rooster (6)
Sylvana (7)
Safari† (4)
Venezia
Vivaldi (5)
Bute (4)
Electra (8)
Elfe
Jelly (6)
Lanorma (7)
Orchestra (8)
Perline
Regina
Vales Sovereign (7)
Volare (5)
Sand 9.8 14.6 18.8
Loamy Sand 12.0 17.9 23.1
Sandy Loam 13.4 20.0 25.8
Sandy Silt Loam 14.4 21.5 27.7
Silt Loam 16.3 24.3 31.4
Clay Loam/Clay‡ 14.4 21.5 27.7
Notes: SMD for top 25 cm of ridge and stone-free ridge profile. This can be calculated by water balance (‘model’), directly measured or converted from soil water tension. †Marabel and Safari: tentative. ‡Excessively cloddy soils may need to be maintained at a smaller SMD. Values in () are the rankings for common scab resistance in Potato Council Variety Database. 1 = most susceptible, 9 =fully resistant.
0
1
2
3
4
5
6
0
10
20
30
40
50
60
21-May 11-Jun 02-Jul 23-Jul 13-AugD
aily
wat
er u
se (
mm
)
SMD
/Irr
igat
ion
/Dra
inag
e (m
m)
Standard 15 mm
SMD
Limiting
Scab
Irrig
Drain
PotETp
ActETp
Packing scab: soil moisture deficits
Packing scab: soil moisture deficits
0
1
2
3
4
5
6
0
10
20
30
40
50
60
21-May 11-Jun 02-Jul 23-Jul 13-AugD
aily
wat
er u
se (
mm
)
SMD
/Irr
igat
ion
/Dra
inag
e (m
m)
Half-frequency 25 mm
SMD
Limiting
Scab
Irrig
Drain
PotETp
ActETp
Tuber initiation (TI)
Pathogenic Streptomyces populations Maris Piper
0.0E+00
4.0E+04
8.0E+04
1.2E+05
1.6E+05
0 1 2 3 4 5
Weeks after tuber initiation
txtA
(co
pie
s/g
)
Rainfed
Scheduled
Over-irrigated
Vales Sovereign
0.0E+00
4.0E+04
8.0E+04
1.2E+05
1.6E+05
0 1 2 3 4 5
Weeks after tuber initiation
txtA
(co
pie
s/g
)
Rainfed
Scheduled
Over-irrigated
Packing scab: emergence / TI Emergence TI
(Days) 50 % First to 50 % First to 90 % 50 %
Estima 37 4 6 15
Jelly 38 3 5 19
Juliette 38 4 7 19
Lanorma 39 4 8 15
Leontine 36 5 7 12
Maris Peer 33 4 7 16
Maris Piper 38 3 7 17
Melody 38 2 6 18
Nectar 36 3 5 19
Red Fantasy 40 5 9 22
Rooster 38 3 7 18
Saxon 39 4 7 15
Soraya 38 2 5 18
Vales Sovereign 45 7 27 18
Mean 38 4 8 Most 17 ± 2
Packing demonstration: common and powdery scab
Common scab Greening Cracking Powdery scab
Variety SMD
Incidence
(%)
Packable
(%)
Severity
(% SA)
Incidence
(%)
Incidence
(%)
Incidence
(%)
Cankerous
(%)
Estima 10 100 100 0.55 4 9 64 32
20 100 100 0.62 5 23 4 7
Jelly 10 98 100 0.49 2 0 4 2
20 94 100 0.51 13 0 0 0
Juliette 10 95 100 0.47 16 2 5 2
20 100 100 0.57 7 2 2 0
Lanorma 10 100 100 0.52 5 0 13 4
20 100 100 0.57 13 11 2 0
Leontine 10 100 100 0.60 3 0 5 0
20 100 97 1.37 0 2 0 0
M Peer 10 96 98 0.83 4 0 16 7
20 100 98 1.24 2 4 0 0
M Piper 10 100 100 0.86 0 0 9 7
20 100 91 2.55 0 11 2 0
Melody 10 100 96 1.54 2 2 4 4
20 100 100 0.81 0 3 0 2
Nectar 10 100 100 0.55 4 2 27 13
20 100 98 1.00 2 22 7 0
Red Fantasy 10 100 100 0.54 5 0 21 4
20 100 96 1.31 4 9 4 4
Rooster 10 96 100 0.48 6 6 8 4
20 96 100 0.69 6 4 2 2
Saxon 10 100 100 0.80 2 6 6 4
20 100 100 0.96 11 2 0 9
Soraya 10 100 100 0.75 6 4 22 8
20 100 100 0.82 7 5 4 0
V Sovereign 10 91 100 0.62 2 4 20 4
20 95 100 0.60 0 9 2 2
Maris Piper 10 mm SMD 20 mm SMD
Summary • Maris Piper worse common scab with infrequent
irrigation, slightly worse in Leontine and Red Fantasy
• Melody slightly better common scab with infrequent irrigation
• Powdery scab increased with frequent irrigation
• Cracking increased with frequent irrigation
• Emergence period short except for Vales Sovereign
• Very short emergence-TI in Leontine, long in Red Fantasy
www.niab.com/NIAB_CUF_Irrigation_Scheduling
Nitrogen
Trials conducted by NIAB CUF • N * Irrigation (sandy loam, 80 % S, 13 % C)
• N (260 kg) • Standard Split N
• All N in seedbed
• Irrigation • Standard (15 mm @ 15 mm SMD)
• Frequent (2 x 8 mm rather than 15 mm dose)
• Over-water (25 mm @ 15 mm SMD)
• Sulphur (sponsored by CUPGRA)
N treatments (260 kg/ha total)
• Standard split N • 20 kg N as DAP 24 March
• 80 kg N as Chafer N30+S 24 March
• 80 kg N as Chafer N30+S 10 May
• 80 kg N as Extran 16 June
• 30 kg N considered as a top up due to rain, but not applied
• Seedbed N • 20 kg N as DAP 24 March
• 240 kg N as Chafer N30+S 24 March
N * Irrig: ground covers
0
20
40
60
80
100
12-May 02-Jun 23-Jun 14-Jul 04-Aug 25-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 O-water Irrig, seedbed N
N * Irrig: yield (all treatments) Irrig
N
Stems
(000/ha)
Tubers >10 mm (000/ha)
Tubers <40 mm (000/ha)
Yield >40 mm
(t/ha)
>90 mm length
(%)
DM (%)
DM yield (t/ha)
Std Split 76 (± 1.6)
414 (± 23.9)
99 (± 11.4)
66.8 (± 3.46)
93 (± 1.1)
21.8 (± 0.11)
15.0 (± 0.69)
Seedbed 76 (± 12.3)
396 (± 45.1)
79 (± 28.4)
70.6 (± 5.78)
94 (± 1.7)
22.8 (± 0.72)
16.6 (± 1.88)
Freq Split 67 (± 6.9)
352 (± 35.3)
42 (± 9.6)
73.2 (± 10.05)
89 (± 3.7)
22.7 (± 0.49)
16.9 (± 2.40)
Seedbed 61 (± 4.2)
287 (± 47.9)
33 (± 14.2)
68.4 (± 1.08)
95 (± 2.4)
21.9 (± 0.34)
15.2 (± 0.44)
O-water Split 77 (± 18.2)
512 (± 129.0)
136 (± 61.2)
64.7 (± 9.05)
89 (± 9.5)
21.4 (± 1.19)
14.6 (± 2.95)
Seedbed 75 (± 12.9)
340 (± 75.1)
45 (± 41.8)
65.9 (± 1.99)
93 (± 3.2)
21.7 (± 0.44)
14.5 (± 0.79)
N * Irrig: yield (N means) Irrig
N
Stems
(000/ha)
Tubers >10 mm (000/ha)
Tubers <40 mm (000/ha)
Yield >40 mm
(t/ha)
>90 mm length
(%)
DM (%)
DM yield (t/ha)
Split N 73 (± 8.9)
426 (± 62.7)
92 (± 27.4)
68.2 (± 7.52)
90 (± 4.8)
22.0 (± 0.59)
15.5 (± 2.01)
Seedbed 70 (± 9.8)
341 (± 56.0)
52 (± 28.1)
68.3 (± 2.95)
94 (± 2.4)
22.1 (± 0.50)
15.4 (± 1.04)
N * Irrig: quality (Irrig and N means)
Irrig
N
Greens
(%)
Cracks
(%)
Dolls (%)
Brown centre
(%)
Hollow heart
(%)
Fry colour (USDA)
Split N 0 (±0.9)
3 (± 1.6)
3 (± 4.1)
17 (± 4.3)
8 (± 10.3)
n/a
Seedbed 1 (± 2.6)
6 (± 3.3)
4 (± 3.0)
15 (± 8.3)
7 (± 10.9)
n/a
Soil mineral N from soil cores
Soil NO3 sensors (Tony Millar, JIC + Agrii)
50
Water input and drainage SPot Farm East Elveden Standard irrigation and standard N application
-200
-100
0
100
200
300
400
500
600
1 Apr 1 May 31 May 30 Jun 30 Jul 29 Aug 28 Sep
Cu
mu
lati
ve r
ain
, irr
igat
ion
an
d d
rain
age
(mm
)
Rain
Planting Emergence 55 DAE
273 mm
Rain + Irrigation 433 mm
Drainage below 60 cm
- 96 mm
51
Water input and drainage SPot Farm East Elveden Over-watered and all N in seedbed
-200
-100
0
100
200
300
400
500
600
1 Apr 1 May 31 May 30 Jun 30 Jul 29 Aug 28 Sep
Cu
mu
lati
ve r
ain
, irr
igat
ion
an
d d
rain
age
(mm
)
Planting Emergence 55 DAE
Rain
273 mm
Rain + Irrigation
532 mm
Drainage below 60 cm
- 191 mm
52
0
20
40
60
80
100
1 May 1 Jun 2 Jul 2 Aug 2 Sep 3 Oct
Gro
un
d c
ove
r (%
)
Standard Irrigation Standard Split N
Over-watered Irrigation All N in Seedbed
Standard Irrigation standard split N
Over-watered all N in seedbed
Total FW yield (t/ha) 68.9 ± 1.96 67.0 ± 1.38
Effect of N and water application strategy on yield. Russet Burbank, SPot Farm East Elveden 2016
NB Unreplicated strips
53
Effect of rainfall and irrigation strategy on estimates of N leaching at SPot Farm East
0
20
40
60
80
100
120
140
160
0 20 40 60 80 100 120 140 160 180 200
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
Summary
• No effect of nitrogen placement or timing on ground cover development or duration
• No effect of nitrogen regime on yield or quality
• Less soil nitrogen at 50-60 cm at harvest in over watered than in standard irrigation
Sulphur CUPGRA
Sulphur: ground covers
0
20
40
60
80
100
12-May 02-Jun 23-Jun 14-Jul 04-Aug 25-Aug
Gro
un
d c
ove
r (%
)
No S
AS
S + AN
Sulphur: petiole sap test 11 August (mg/l)
Treatment S NH4 NO3 P K Mg Mn Mo
No S 136 5.3 56.3 65.9 4868 453 14.7 0.45
AS 251 11.3 72.0 66.0 4879 511 17.8 0.16
AN + S 189 6.8 54.8 59.3 4760 489 17.2 0.20
S.E. (14 D.F.) 20.9 3.42 17.80 2.34 83.9 22.6 1.77 0.132
AS > No S
Sulphur: yield Treatment
Stems
(000/ha)
Tubers >10 mm (000/ha)
Yield >40 mm
(t/ha)
>90 mm length
(%)
DM (%)
DM yield (t/ha)
No S 70 278 68.5 94 21.8 15.0
AS 69 258 62.7 92 21.8 13.7
S + AN 71 269 63.1 94 22.2 14.1
S.E. (14 D.F.) 2.2 9.5 2.00 1.3 0.27 0.56
Sulphur: quality
Irrig
Greens
(%)
Cracks
(%)
Dolls (%)
Brown centre
(%)
Hollow heart
(%)
Fry colour (USDA)
No S 0.7 6.0 6.6 19 1.9 n/a
AS 0.8 5.5 8.9 18 6.9 n/a
S + AN 0.9 8.1 6.7 18 4.4 n/a
S.E. (14 D.F.) 0.41 1.19 1.98 3.5 1.89
Summary
• No effect of S!