nutrient management in brassica cropscemonterey.ucanr.edu/files/183678.pdfnitrogen management of...
TRANSCRIPT
Nutrient Management gIn Brassica Crops
Richard SmithUC Cooperative Extension, Monterey County
Nitrogen Management of Leafy VegetablesLeafy Vegetables
• Nitrogen management ofNitrogen management of vegetables in the coastal production districts is underproduction districts is under greater scrutiny
• Growers will need to report N usage to the Central Coast gRegional Water Quality Control Board in 2014Board in 2014
Nitrogen Management of Leafy VegetablesLeafy Vegetables
• As a result, growers are lookingAs a result, growers are looking for tools to improve nitrogen use efficiencyefficiency
Nitrogen Management of Leafy VegetablesLeafy Vegetables
• An important tool in nitrogenAn important tool in nitrogen management is to account for residual N mineralized from priorresidual N mineralized from prior crop residues
Nitrogen Management of Leafy VegetablesLeafy Vegetables
• Another way of improvingAnother way of improving nitrogen use efficiency is to capture nitrate that may havecapture nitrate that may have moved to deeper in the soil profile
d b i it b k t th fand bring it back to the surface for another opportunity to use it
Nitrogen Management of Leafy VegetablesLeafy Vegetables
• Crops like sugar beets and small grains, when they were viable g , ycrops in the Salinas Valley, were capable of retrieving nitrogencapable of retrieving nitrogen from deeper in the soil profileC d thi b t• Cover crops can do this but we are limited in their use
Nitrogen Management of Leafy VegetablesLeafy Vegetables
• In recent studies funded by the Fertilizer Research and Education Program (CDFA), we observed that cole crops can scavengethat cole crops can scavenge nitrate
Nitrogen Uptake by Broccoli, Cauliflower and Cabbage
Nitrogen Dynamics in ColeNitrogen Dynamics in Cole Crops – Summer ProductionCrops Summer Production
Crop Dry BiomassLbs/A
Percent Nitrogen
Percent Potassium
Potassium UptakeLbs/A
PhosphorusUptakeLbs/ALbs/A Lbs/A Lbs/A
Broccoli 8,585 4.0 4.2 360 44Cauliflower 6 930 4 1 4 3 299 45Cauliflower 6,930 4.1 4.3 299 45Cabbage 11,564 3.0 3.2 361 42
Nitrogen Dynamics in ColeNitrogen Dynamics in Cole Crops – Summer ProductionCrops Summer Production
Crop Harvest Leaves Stalks Roots Residue ProductN/A N/A N/A N/A N/A
Broccoli 99 198 41 11 23899 198 41 11 238Cauliflower 61 204 20 10 224C bb 164 9Cabbage 188 164 ‐‐‐ 9 163
Nitrogen Dynamics in ColeNitrogen Dynamics in Cole Crops – Summer ProductionCrops Summer Production
Crop Fertilizer Crop Uptake ScavengedCrop Fertilizerapplied
Crop Uptake Scavenged from soil
Broccoli 181 337 155C liflCauliflower 260 285 21Cabbage 215 337 97g 215 337 97
Nitrogen Uptake CurveSummer Broccoli
Summer broccoli400
500
ssssssssssssssss
b/ac
re)
300
400
y = 5.72x - 157.9R2 = 0.89
ssssssssssssssss
N (l
b
200
100
Days after germination water
0 20 40 60 80 1000
Nitrogen Dynamics in ColeNitrogen Dynamics in Cole Crops – Winter ProductionCrops Winter Production
Crop Dry Biomass
Percent Nitrogen
Percent Potassium
Potassium Uptake
PhosphorusUptake
Broccoli 5,539 4.5 3.3 194 32Cauliflower 6 490 4 2 3 7 236 36Cauliflower 6,490 4.2 3.7 236 36
Nitrogen Dynamics in ColeNitrogen Dynamics in Cole Crops – Winter ProductionCrops Winter Production
Crop Harvest Leaves Stalks Roots ResidueCrop HarvestProductN/A N/A N/A N/A
Residue
N/A
Broccoli 94 128 29 8 156Broccoli 94 128 29 8 156
Cauliflower 70 160 14 9 175
Nitrogen Dynamics in ColeNitrogen Dynamics in Cole Crops – Winter ProductionCrops Winter Production
Crop Fertilizerapplied
Crop Uptake
Scavenged from soilapplied
N/AUptakeN/A
from soilN/A
Broccoli 272 249 23+Broccoli 272 249 23+Cauliflower 351 273 78+
Nitrogen Uptake CurveWinter Broccoli
400
Winter broccoli300
ssssssssssssssss
b/ac
re)
200
y = 2.62x - 153.8R2 = 0.71
N (l
b
100
0
Days after germination water
0 20 40 60 80 100 120 140 160
Nitrogen Uptake by Broccoli, Cauliflower and Cabbage
• Where is the extra nitrogen coming from inWhere is the extra nitrogen coming from in the summer‐grown broccoli?
• Is broccoli is acting like a cover crop in that it• Is broccoli is acting like a cover crop in that it is bringing up nitrate from deeper in the root zone?zone?
Rooting Depth and Nitrate at the End of the Growing Season
Spinach Root Distribution
9
6
7
8
4
5
roots/in
2
1
2
3
0
0‐4 4‐8 8‐12 12‐16 16‐20 20‐24
Depth (in)
Nitrate Distribution in Spinach Bedst H tat Harvest
20
25
15
N (m
g/kg soil)
5
10
NO3‐N
0
0‐4 4‐8 8‐12 12‐16 16‐20 20‐24
Depth (in)
Root Density of Lettuceat Various Soil Depths
Bed Width (inches)
5 10 15 20 25Plant Line Plant Line
Drip lineDrip line
5 10 15 20 25
5 0102030
Root N
umes
)
10
304050 60 70
mber / 100 cm
2D
epth
(inc
he
15
D
20
25
Soil Nitrate Distribution in Lettuce
Nitrate-N (ppm)Bed width (inches)
10 20 30 40 50
5
Plant row Plant rowDrip tapeNitrate‐N (ppm)
5
10
0 2 4 6 8 10
ches
)
10
15
012 14 16 18 20 22
Dep
th (i
nc 15
20
22 24 26
20
2525
End of Crop Nitrate DynamicsEnd of Crop Nitrate Dynamics
• Nitrate can accumulates at the bottom edgeNitrate can accumulates at the bottom edge of the root zone of lettuce and spinach
• Nitrogen from crop residues is also disced• Nitrogen from crop residues is also disced into the soil, enriching the upper soil layers with nitratewith nitrate
Measurements of nitrate in soil at various depths in the root zone
following a prior crop and over thefollowing a prior crop and over the crop cycle of broccoli
Nitrogen in the Top Three Feet of Soil over the Broccoli Crop CycleSoil over the Broccoli Crop Cycle
One Field
90Third foot
60
70
80
90
ppm
First foot
Second foot
20
30
40
50
NO
3-N
p
0
10
preplantearly growthearly growth
late growth harvest
Growth Stage of Broccoli
Residual Soil Nitrogen Utilized by the Broccoli Cropthe Broccoli Crop
One FieldDepth Lbs N/A
1st 58
2nd 70
3rd 263rd 26
Total 154
90Third foot
60
70
80
90
First foot
Second foot
ppm
20
30
40
50
NO
3-N
p
0
10
preplantearly growthearly growth
late growth harvest
Growth Stage of Broccoli
Evaluation of Nitrate in the 1st & 2ndFoot of Soil (5 fields)
4550 First foot
SecondDepth Lbs N/A
1st 40
202530354045 Seco d
foot 1st 40
2nd 24
Total 64
05
101520
BaselineEarly growth
Mid‐growthLate growth
Harvest
Growth Stage of Broccoli
Broccoli Rooting DepthBroccoli Rooting Depth
45
50
34.1”
35
40
5
25
30
-inc
hes
15
20
Dep
th
5
10
0
0.1 0.2 0.3 0.4 0.4 0.5 0.6 0.7 0.8
Portion of the Growth Cycle
Early Mid Late Harvest
Cauliflower Rooting DepthCauliflower Rooting Depth60
5034.1”
30
40
-inc
hes
20
30
Dep
th
10
00.1 0.3 0.4 0.5 0.7 0.8
Portion of the Growth Cycle
90 Day Old Cauliflower Roots90 Day Old Cauliflower Roots
Cabbage Rooting DepthCabbage Rooting Depth50
35
40
45
30.9”
25
30
35
-inc
hes
15
20
5
Dep
th
5
10
0
0.1 0.3 0.4 0.6 0.8Portion of the Growth Cycle
RecommendationsRecommendations• Measure the levels of residual nitrate in the
d f l i h h l f lsecond foot early in the growth cycle of cole crops
• Given that broccoli is taking up nitrogen from the top two feet, this information will give you a better sense of what nitrogen resources are available for that crop
• Careful water management will be necessary to maintain the nitrate in the top two feet pbefore the broccoli roots reach there
RecommendationsRecommendations• All of the cole crops leave sizeable quantities
f i i h i idof nitrate in their crop residue • This nitrate will rapidly mineralize nitrate for subsequent crop use
• Again, careful irrigation will better assure g , gthat this nitrogen is available for subsequent crops that are shallower rootedp