Vegetable Crops Irrigation and Nitrogen Management : Vegetable crop N content in harvested product...

Vegetable Crops Irrigation and Nitrogen Management

Tom Turini

University of California

Agriculture and Natural Resources

Vegetable Crops Advisor

Fresno County

• Background• Consequences of incorrect nitrogen rates• Irrigation in vegetable crops

• Sources and fates of nitrogen• Growth and nitrogen demand in vegetable

crops• Nitrogen uptake in vegetable crops• Field specific management in vegetables

(other N credits and tissue testing)• Recent project on processing tomato

nitrogen management

Presentation Overview



crops


Nitrogen Deficiency –Rare Commercially • Nitrogen is a major component of plants

(chlorophyll, amino acids – protein, genetic material)

• Deficiencies will decrease yield and may decrease quality.

• Symptoms: leaves become light green or yellow, decrease size of all plant structures including

fruit and leaves.

Overview• Basic principles

– Nitrogen cycle

– When and how much

– Consequences of incorrect rates

• Recent developments regarding Nitrogen

• Nitrogen plan worksheet

• Generalizations

Nitrogen Excess – More Common


– Nitrogen cycle





• Generalizations

Increased Leaf and Shoot Growth

• Fewer fruit and smaller vegetative storage organs (tubers)

• .Disease issues increase

• Physiological issues, such as blossom end rot of tomato, pepper; hollow stem of broccoli, tip burn of lettuce

• Bacterial issues, such as bacterial spec in tomato increase due to longer periods of leaf wetness and difficulties in getting contact with bactericides

• Fungal Foliar Diseases: Powdery mildew is favored by higher relative humidity that will be present in a dense canopy


– Nitrogen cycle





• Generalizations

Commodity Quality Decline

• delayed maturity

• lower sugar content

• lower acidity

• reduced firmness

• less volatile production resulting in poor flavor



crops


• Irrigation at rates above ET will

result in leaching

• Lower than optimum irrigation

rates can reduce growth and

reduce N uptake

Influence of irrigation on

N fate

CIMISReference evapotranspiration rates from 235 weather stations in California is available through ‘California Department of Water Resources’

http://www.ipm.ucdavis.edu/WEATHER/wxactstnames.html

Canopy Coverage (%)

0 10 20 30 40 50 60 70 80 90 100

Cro

p C

oeff

icie

nt

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

1.1

1.2

Reference Et (Eto) x Crop Coefficient (Kc)= Crop Et (Etc)

Hansen presentation, 2008

• Water stress during any growth

stage may reduce yield

• Earlier growth stages – more

sensitive to water stress

• Later growth stages – less

sensitive to water stress

Plant Growth Stage

Considerations

T. C. Hsiao, UC Davis

Deficit Irrigation

Irrigation rates are reduced during the last 60 days of the crop to levels below evapotranspiration may not reduce yields in processing tomatoes.

Deficit Irrigation Impact on Processing Tomato Yield and Quality

• Clay loam soil in a comercial Five Points-área field

• Over 3 years, irrigation quantities werereduced to a percentage of Etc durring the last60 days of the crop.

• Soil moisture levels were measured withnutron probes

• Tomato yield was measured with a mechanicalharvester and a scale-equipped trailer.

Applied Water in 2010 in Study

Turini, Munk 2015

2010 Soil Moisture Levels in Study

Turini, Munk 2015

Sources: D. May, B. Hansen(1996); T. Turini, D. Munk (2013)

Influence of Late Season Deficit Irrigation

Depends on Soil

70

Deficit Irrigation

• No yield diferences were observed in thestudy conducted from 2010 to 2012 in theclay-loam soil.

• In 1994 and 1995 a similar study wasconducted in a sandy-loam and there was a 30 to 32% yield reduction at a 50 % deficit.



crops


Sources/Fates of Nitrogen

ACCUMULATION OF SOIL

NITROGEN

N OUTPUTS

N INPUTS

Nitrate

Harvested productFertilizer

Organic amendmentsIrrigation water

AmmoniaNitrous Oxide

Nitric Oxide

VOLITALIZATION DENITRIFICATION

Nitrogen gas

LEACHING OR RUNOFF

Modified from Hartz 2016



crops


General Growth Pattern

0

1

2

3

4

5

6

7

8

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

Dry

bio

mas

s (t

on

s/ac

re)

Weeks after seeding/transplant

cantaloupe processing tomato lettuce


Nitrogen Accumulation in Processing Tomato

0

50

100

150

200

250

300

350

400

0 50 100 150

Bio

mas

s N

(lb

s/ac

re)

Days after transplanting

Nitrogen accumulation follows the same pattern as growth

Data from 4 high-yielding processing tomato fields


Nitrogen Accumulation in Cantaloupe

0

20

40

60

80

100

120

140

160

180

200

0 20 40 60 80 100

Bio

mas

s N

((l

bs/

acre

)

Days after transplanting

Nitrogen accumulation follows the same pattern as growth

Data from 3 high-yielding hybrid cantaloupe fields


Nitrogen Partitioning in Fruiting Crops

0

20

40

60

80

100

120

140

160

180

0 5 10 15 20

Bio

mas

s N

((l

bs/

acre

)

weeks after transplanting

Nitrogen partitioning by processing tomatoes

Generally, fruit represents 50 to 70 percent of total plant uptake in fruiting crops


Generalized Nitrogen Uptake in Vegetable Crops

0

5

10

15

20

25

30

35

40

1 2 3 4 5 6 7 8 9 10 11 12

Cro

p N

up

take

(lb

s/ac

re/w

eek)

weeks after emergence

Harvest of fruiting crops occurs after peak nitrogen uptake rates

Vegetative crops are typically harvested near peak nitrogen uptake rate


Nutrient uptake in processing tomato:

0

10

20

30

40

50

60

5 6 7 8 9 10 11 12 13 14 15

Week after transplanting

We

ek

ly N

up

tak

e

(lb

/ac

re)

N P2O5 K2O

At harvest a high-yield crop (vine and fruit) contains :


Generalized : Vegetable crop N content in harvested productCroptype

lb N/ton of fresh wt

Avg yield (tons/acre)*

Avg. N removed per acre

Fruiting Cantaloupe 3.0 17.50 52.5

Honeydew 2.1 19.92 41.8

Pepper 3.2 17.13 54.8

Tomato 3.1 49.44 153.3

Watermelon 2.0 25.64 51.3

Vegetative Broccoli 11.6 6.3 73.1

Lettuce 4.0 17.0** 68.0

* Fresno County Annual Crop and Livestock Report Agricultural Commissioner’s Report, 2016.

** Average over Fall and Spring Crops, both head and romaine types


Nutrient uptake by high-yield processing tomato

lb / acre

Nutrient total in fruit

N 240 - 280 160 - 200

P2O5 80 - 100 50 - 70

K2O 300 - 450 250 - 350


Nitrogen Uptake Rates

Individual fields can differ wildly in nutrient uptake rates

Fruit yield Crop N uptake (lbs/acre)

Field # (tons/a) Vine Fruit total

1 53 65 179 244

2 56 168 198 366

3 58 139 150 289

4 58 `145 148 293

Luxury Uptake• Nutrient uptake that neither increases yield nor

product quality.• Ten to 20% of total crop yield may be due to luxury

uptake.





(other N credits and tissue testing)


Field-Specific N ManagementSoil nitrate testing in tomatoes Commercial processing tomato field

0

50

100

150

200

250

300

350

1 2 5 8 9 10 12 13 14 15 17 18 19 20

Nit

roge

n (

lbs/

acre

)

Field number

residual NO3-N 20" Seasonal fertilization applied

Horwath et al., 2003

Soil residual NO3-N varied from 23 – 216 lbs/AAverage 80 lbs/A

Grower applied rates varied from 20 to 210 lbs/acre

Example of Nitrogen Balance based on these observations

Expected N requirements

• Expected yield: 55 tons/acre

• Expected N uptake: 246 lbs/acre

– 2.99 lbs/ton; 67% of total N in fruits

• N use efficiency: 90%

• Total N requirement: 274 lbs/acre (from all sources)

From Geisseler 2017

N budget Field 1

N sinks and sources lbs N/acre

N uptake 246 lbs/acre

N efficiency 90%

N requirement 274

N in irrigation water 0 lbs/acre

Residual soil nitrate 130 lbs/acre

N credits 130

Fertilizer application rate 144


0

50

100

150

200

250

300

350

1 2 5 8 9 10 12 13 14 15 17 18 19 20

Nit

roge

n (

lbs/

acre

)

Field number





N budget example Field 2



N efficiency 90%

N requirement 274

N in irrigation water 0 ppm


N credits 20



0

50

100

150

200

250

300

350

1 2 5 8 9 10 12 13 14 15 17 18 19 20

Nit

roge

n (

lbs/

acre

)

Field number





N budget Field 3



N efficiency 90%

N requirement 274

N in irrigation water 0 lbs/acre


N credits 210



0

50

100

150

200

250

300

350

1 2 5 8 9 10 12 13 14 15 17 18 19 20

Nit

roge

n (

lbs/

acre

)

Field number





Field-Specific N ManagementContribution of prior crop residue

-20

0

20

40

60

80

0 1 2 3 4 5 6 7 8 9 10 11 12

Nit

roge

n m

iner

aliz

atio

n

(% o

f re

sid

ue)

Weeks after incorporation

< 2.0 % N 2.50% > 3.0 %

Generally, after 90 days following incorporation of crop residue, it begins to function as existing soil organic N


Plant Tissue Testing

Growth stage Total plant N content

N uptake/day

Daily uptake as % biomass N

Early bloom 25 1 4

Mid-fruit set 80 3.5 4

First red fruit 160 4.5 3

Leaf total N substantially above the sufficiency level indicates

sufficient biomass N to accommodate 7+ days of crop growth.

Advantage of leaf total N: changes slowly


0

1

2

3

4

5

6

7

0 500 1000 1500 2000

Leaf

to

tal N

(%

)

Growing degree days

Plant Tissue Testing

Leaf total N monitoring, Tomato Example

●Red symbols from fields in which N availability limited yield●blue symbols from fields with adequate N to maximize yield

Early Flowering First red fruitFull bloom

sufficiency

Limitation of leaf total N: doesn’t reflect soil N availability until the high N uptake period, so it is a flawed guide to early season N






nitrogen management


Statewide 2016-17 Site Specific Nitrogen Management Study in Processing Tomatoes

Led by Daniel Geisseler (UC Davis Nutrient

Management Specialist)

Data collection in commercial fields in 2016

• Sites: - 2 sites near Woodland

- 3 sites near Stockton

- 1 site near Huron

• Data: - Canopy development (infrared camera)

- ET estimates from Tule stations

- N uptake

(repeated plant sampling)From Geisseler 2017

Expected N uptake

N in tomatoes: 2.99 lbs/ton

N in vines: 33% of total N

For a 55-ton total yield:

From Geisseler 2017

Expected N requirements

• Expected yield: 55 tons/acre

• Expected N uptake: 246 lbs/acre

– 2.99 lbs/ton; 67% of total N in fruits

• N use efficiency: 90%

• Total N requirement: 274 lbs/acre (from all sources)

From Geisseler 2017

N sources at field site

• No nitrate in irrigation water

• Residual soil nitrate:– 1st foot: 13 ppm 45.4 lbs/acre

– 2nd foot: 7.7 ppm 27 lbs/acre

• Assumption: 50% of nitrate in 1st foot and 90% in 2nd foot are available

Available soil nitrate: 47 lbs/acre

Fertilizer N needed (incl. starter): 225 lbs/acre From Geisseler 2017

N budget for UC Davis trial



N efficiency 90%

N requirement 274

N in irrigation water 0 ppm


N credits 47


From Geisseler 2017

Replicated trial at UC Davis

• 3 nitrogen treatments:

– N_175: Optimal N minus 50 lbs N/acre

– N_225: Optimal N

– N_275: Optimal N plus 50 lbs N/acre

• Irrigation in all treatments was 100% ET

• 5 replicates

• Plot size: 3 beds x 200 feet

From Geisseler 2017

Trial management

• Transplanting date: 05/01/2017

• Fertilization:

– Starter: 30 gal/acre of 8-24-6, Zn

– 5 weekly fertigations of UAN between 06/01 and 06/29

– Two applications of K-thiosulfate in July (total of 100 lbs K2O/acre)

• Harvest date: 08/25/2017

From Geisseler 2017

Fertilization program

Residual soil nitrate not included

From Geisseler 2017

Marketable yield

• Average marketable yield: 58 tons/acre

• No statistically significant differences among treatments

From Geisseler 2017

Why are there no treatment effects?

• We may have overestimated N uptake

• We did not account for N mineralization during the growing season

From Geisseler 2017

Measured N uptake

From Geisseler 2017

Conclusions

• At common N application rates, plants take up more N than needed (luxury consumption)

• Root access to nitrate above the drip line is a rough estimate

• Even in soils with a low soil organic matter content, N mineralization during the season contributes to N supply

From Geisseler 2017





nitrogen management


Acknowledgements • Tim Hartz (developed much of the material

presented)

• Daniel Geisseler (leading a current study on Nitrogen Management in tomato)

• CDFA Fertilizer Research and Education Program (FREP)

• California Tomato Research Institute (CTRI)

• UC ANR California Institute for Water Resources

• Growers

Vegetable Crops Irrigation and Nitrogen Management : Vegetable crop N content in harvested product...

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