SPot East 2018 Results

Nitrogen work over three years

Marc Allison & Mark Stalham

Hypothesis: does N application drive yield?

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100

0 50 100 150 200 250 300 350 400

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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250

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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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400

500

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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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500

0 50 100 150 200 250 300 350

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

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7

8

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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160

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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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