Nitrate-N residues, soil mineral N balance and
N fertilizer recommendation
in vegetable fields in Flanders
Mia Tits, Annemie Elsen,
Hilde Vandendriessche and Jan Bries
Soil Service of Belgium
W. de Croylaan 48,
3001 Heverlee, Belgium
www.bdb.be
Nutrihort, September 16-18, 2013, Ghent, Belgium
Soil Service of Belgium
Nitrate-N residues, soil mineral N balance and
N fertilizer recommendation
in vegetable fields in Flanders
Definition:
Nitrate-N residue
= residual nitrate-N in the soil (0-90 cm) in autumn
= measured during the period from 1/10 – 15/11
= expressed as kg nitrate-N per hectare
= direct link with risk of nitrate leaching to groundand surface water during winter
Nutrihort, September 16-18, 2013, Ghent, Belgium
Soil Service of Belgium
kg nitrate-N.ha-1
Evolution of the nitrate N residues in agricultural
crops in Flanders
Evolution of the weighted average nitrate-N-residue in Flanders based on the
results of control measurements performed by the Manure Bank (VLM 2012)
Nutrihort, September 16-18, 2013, Ghent, Belgium
Soil Service of Belgium
Evolution of the nitrate N residues in vegetable crops
in Flanders
Average nitrate-N residues per year for cauliflower and leek
180
nitrate-N (kg N.ha-1)
160
140
120
100
cauliflower
80
leek
60
40
20
0
2009
2010
2011
2012
source: Soil Service of Belgium
Nutrihort, September 16-18, 2013, Ghent, Belgium
Soil Service of Belgium
Distribution of nitrate-N residues in the soil profile
Distribution of the residual nitrate-N in the soil profile, per crop (VLM 2010)
100%
90%
80%
70%
60%
50%
40%
0-30
30%
30-60
20%
60-90
10%
0%
Nutrihort, September 16-18, 2013, Ghent, Belgium
5Soil Service of Belgium
Nitrate residue, influenced by many factors
organic
fertilization
mineral
fertilization
N uptake by
crops
N uptake by
catch crops
volatilization and
denitrification
harvest
nitrate stock
spring
N leaching
N mineralization
spring
Nutrihort, September 16-18, 2013, Ghent, Belgium
nitrate residue
(1/10 – 15/11)
N mineralization
from crop residues
N mineralization
autumn
N leaching
Soil Service of Belgium
N-fertilization using the N-index method
1. N-requirements
product
crop residue
2. N-index  N-availability during cropping season,
depending on crop and parcel characteristics
N-index
+ N-stock (~rooting depth)
- effect soil texture/structure, low pH
+ mineralization:
- leaching during cropping season
- OM (%C)
- green manure
- crop residue
- organic fertilizer
Nutrihort, September 16-18, 2013, Ghent, Belgium
Soil Service of Belgium
N-fertilization using the N-index method
1. N-requirements
product
crop residue
2. N-index  N-availability during cropping season,
depending on crop and parcel characteristics
N-index
N-advice
3. N-advice
Nutrihort, September 16-18, 2013, Ghent, Belgium
Soil Service of Belgium
Calculation of the soil mineral N balance
N inputs
N outputs
Mineral N stock in the soil profile (0-90 cm)
N uptake by crops
Expected N mineralization from soil organic matter N uptake by catch crops
Expected N mineralization from crop residues
N losses through leaching
Applied mineral N fertilization
N supply from applied organic fertilization
Total input (incl. N stock)
Total output
Expected residue (input-output)
Nitrate-N residue
Balance deviation
Nutrihort, September 16-18, 2013, Ghent, Belgium
Soil Service of Belgium
Soil mineral N balance – case 1
400
(cauliflower-)cauliflower(-rye-grass)
300
planting
balance
harvest
crop uptake
200
crop residues
100
fertilization
mineralization
0
stock
1/4
16/4
1/5
16/5
1/6
16/6
1/7
16/7
1/8
16/8
1/9
16/9 1/10
-100
N inputs
Mineral N stock in the soil profile (April)
Expected N mineralization from soil organic matter
Expected N mineralization from crop residues
Applied mineral N fertilization
N supply from applied organic fertilization
Total input (incl. N stock)
Nutrihort, September 16-18, 2013, Ghent, Belgium
kg N.ha-1 N outputs
88 N uptake by crops
165 N uptake by catch crops
40 N losses through leaching
kg N.ha-1
250
0
0
190
16
499 Total output
561
Expected residue (input-output)
249
Nitrate-N residue (September 27th)
311
Balance deviation
10 -62
Soil mineral N balance – case 1
400
(cauliflower-)cauliflower(-rye-grass)
balance
300
crop uptake
200
crop residues
100
fertilization
mineralization
0
stock
1/4
16/4
1/5
16/5
1/6
16/6
1/7
16/7
1/8
16/8
1/9
16/9 1/10
-100
excessive N fertilization of 190 kg N.ha-1
(advice: 145 kg N.ha-1)
mineralization of N-rich
crop residues in september
late N-uptake by
catch crop rye-grass
high nitrate-N residue
Nutrihort, September 16-18, 2013, Ghent, Belgium
Soil Service of Belgium
Soil mineral N balance – case 2
500
(carrots-)cauliflower-cauliflower
balance
400
300
planting 1
harvest 1
harvest 2
planting 2
200
leaching
crop uptake
crop residues
fertilization
100
mineralization
0
stock
1/3 16/3 1/4 16/4 1/5 16/5 1/6 16/6 1/7 16/7 1/8 16/8 1/9 16/9 1/10 16/10 1/11
-100
N inputs
kg N.ha-1 N outputs
Mineral N stock in the soil profile (April)
138 N uptake by crops (292+180)
Expected N mineralization from soil organic matter
110 N uptake by catch crops
Expected N mineralization from crop residues
124 N losses through leaching
Applied mineral N fertilization (169+140)
309
N supply from applied organic fertilization
81
Total input (incl. N stock)
762 Total output
Expected residue (input-output)
Nitrate-N residue (September 27th)
Nutrihort, September 16-18, 2013, Ghent, Belgium
Balance deviation
kg N.ha-1
472
0
44
739
247
224
12
23
Soil mineral N balance – case 2
500
(carrots-)cauliflower-cauliflower
balance
400
leaching
300
crop uptake
200
crop residues
fertilization
100
mineralization
0
stock
1/3 16/3 1/4 16/4 1/5 16/5 1/6 16/6 1/7 16/7 1/8 16/8 1/9 16/9 1/10 16/10 1/11
-100
excessive N fertilization
lower N-uptake by second crop
-1
for both crops (81+169 & 140 kg N.ha ) (unfavourable conditions)
(advice: 169 & 112 kg N.ha-1)
late harvest,
important N-supply from
no catch crop
residues of first crop
high nitrate-N residue
Nutrihort, September 16-18, 2013, Ghent, Belgium
Soil Service of Belgium
Soil mineral N balance – case 3
250
(cabbage-)leek
200
balance
planting
leaching
150
crop uptake
100
crop residues
50
fertilization
0
-50
mineralization
1/4 16/4 1/5 16/5
1/6 16/6
1/7 16/7 1/8 16/8 1/9 16/9 1/10 16/10
stock
-100
N inputs
Mineral N stock in the soil profile (April)
Expected N mineralization from soil organic matter
Expected N mineralization from crop residues
kg N.ha-1 N outputs
132 N uptake by crops
0
0 N losses through leaching
21 Nitrate-N residue (September 27th)
N supply from applied organic fertilization
52
296 Total output (incl. residue)
Expected residue (input-output)
Nutrihort, September 16-18, 2013, Ghent, Belgium
110
90 N uptake by catch crops
Applied mineral N fertilization
Total input (incl. N stock)
kg N.ha-1
Balance deviation
36
147
293
149
14
2
Soil mineral N balance – case 3
250
(cabbage-)leek
200
balance
150
leaching
crop uptake
100
crop residues
50
fertilization
0
-50
mineralization
1/4 16/4 1/5 16/5
1/6 16/6
1/7 16/7 1/8 16/8 1/9 16/9 1/10 16/10
stock
-100
high N stock
in spring
early application of organic
fertilizer  leached to
deeper soil layers by the time
of crop growth
low N-uptake due to slow initial
growth, shallow root system and
N leached to deeper soil layers
supplementary late N fertilization
to improve yield (quality)
high nitrate-N residue
Nutrihort, September 16-18, 2013, Ghent, Belgium
Soil Service of Belgium
Conclusions
Major bottlenecks of vegetable growing in terms of nitrate residue:
- considerable amount of rapidly degradable crop residues
 high N mineralization in a short period after harvest
- shallow root systems, N in deeper soil layers is not absorbed
 N distribution in soil profile very important
 N availability at right time very important
 N uptake seriously affected by weather conditions
- late harvest in vegetative stage requires sufficient N supply
- sowing of catch crop often practically impossible
 Importance of accurate N-fertilization (dose and timing)
 N fertilization recommendations based on
 crop requirements,
 soil analysis,
 knowledge about mineral N becoming available during the growing season.
 Soil mineral N balance = helpful tool
Nutrihort, September 16-18, 2013, Ghent, Belgium
Soil Service of Belgium