fertility management. irrigated potato production

Potato Science Lecture 12

Fertility Management

Irrigated Potato Production

Important NutrientsPrimary macronutrients

Nitrogen Phosphorus Potassium

Total potato plant N, P, and K Uptake

0

50

100

150

200

250

300

350

0 20 40 60 80 100

Vegetative Growth

Tuber Initiation

Tuber Bulking Maturation

K

N

P

Days After Emergence

Nu

trie

nt

Up

take

(lb

/ac)

Total Potato Plant N, P, and K Uptake Rates at Aberdeen

0

1

2

3

4

5

0 20 40 60 80 100 120

Days After Emergence

Nu

trie

nt

Up

take R

ate

s (

lb/a

c/d

ay)

K

N

P

Early-Season Soil Nutrient Placement

Fertilizer Placement

Dry Fertigation

P, K

N

Foliar

Relative Nutrient Mobility in SoilNitrogen – Mobile (nitrate>urea>ammonium)

Potassium – moderately low mobility

Phosphorus – low mobility

NitrogenNecessary for protein and

chlorophyllUsed in large quantities by plantsQuantity available fluctuates rapidlyShortage associated with marked

yield lossApplication important in all soils

Soil N Cycle

LEACHING (NO3-)

Nitrogen Deficiency Symptoms

General chlorosis (pale green color)

Younger leaves turn darker green, old leaves remain yellow

Upward cupping of deficient leaflets when severe

Potato Variety Nitrogen Response Trials Aberdeen, 2005

Soil AnalysisOne composite sample per 20-25

acres

0-12 inch sampling depth for potatoes

Combine 10-20 samples (zig-zag pattern)

Random but accurate samples

Total N Recommendations for Russet Burbank Potatoes

Potential Yield (cwt/acre)

Soil NO3-N (0-12 in depth)

300 400 500 600

ppm ---------------------------lb N/acre --------------------------

0 200 240 280 320

5 180 220 260 300

10 160 200 240 280

15 140 180 220 260

20 120 160 200 240

25 100 140 180 220

Nitrogen Fertilizer Management Program

Apply up to 25-60% of N prior to planting

Apply remainder of N (40-75%) through the irrigation system during tuber development according to crop requirements

Slow release or controlled release N fertilizers applied preplant can be used to reduce N leaching

Preplant N applicationsNitrogen (partial application)25-30% on sandy soils30-40 % on sandy loam soils40-60 % on silt loams

Nitrogen fertilizers – urea, mono-ammonium phosphate, ammonium sulfate, ammonium polyphosphate

In-Season N ApplicationsIn-Season N Applications

Begin after tuber initiation and adjust according to tuber bulking rates and weekly petiole N concentrations

Cut-off 3 to 4 weeks before vine kill

Begin after tuber initiation and adjust according to tuber bulking rates and weekly petiole N concentrations

Cut-off 3 to 4 weeks before vine kill

Target = Total Seasonal N Requirement - preplant + sidedress applications

Calculating In-Season N Application Rates

Based on lb N/ac/day or week, which changes according to crop demand

Once tuber bulking begins, weekly crop N requirements can be estimated based on relationships between tuber growth rate and plant N uptake

Daily N uptake rates for different potato cultivars range from about 2 to 5 lb N/ac/day depending on the tuber-bulking rate

Can be applied as dry or liquid N fertilizers

Calculating In-Season N Application Rates

Russet Burbank requires about 3-4 lb N/ac/day (20-25 lb N/week) to prevent the loss of both N and dry matter from the tops and roots to the tubers during tuber bulking

Assuming 75-80% plant N uptake efficiency for injected N fertilizer, about 30 lb N/ac would satisfy crop N requirements for a week

Adjustments to projected rates to account for N mineralization should be based on weekly petiole nitrate tests

0 60 120 180 240300

350

400

450

500

550

600

650

Nitrogen Rate (lb N/A)

Tota

l Yie

ld (c

wt/

A)

A03158-2TE

Russet Burbank

150130

Total Yield Response to N for A03158-2TE and Russet Burbank at Aberdeen ID, 2013

460

610

506

423

Tissue AnalysisPetiole analysis the most commonSample 4th petiole Sample under consistent conditionsDry the tissue immediatelyPrivate and public labsBase applications on sufficiency

A03158-2TE Petiole Nitrates, 2013

27-Jun 11-Jul 25-Jul 30-Jul0

5000

10000

15000

20000

25000

30000

0

60

120

180

240

Recommended petiole and soil (0-18 inches) NO3-N concentrations for Russet Burbank potatoes during different growth stages

Tuber Tuber Sample Vegetative Initiation Bulking Maturation

------------- NO3-N (ppm) -------------

Petiole ----- 20,000-25,000 15,000-20,000 10,000-15,000

Soil > 20 20 15-20 < 15

From Rowe, 1993

Factors Affecting Petiole Nitrogen Concentrations Plant Factors:

photosynthesisdry matter productionN metabolismtranspiration

Soil Factors:temperaturemoisturemineralizationNH4

+/NO3-

physical conditions

Root Factors:carbohydrate supplyroot healthroot length / depth

Critical Time Period – N builds up in (or is applied to) soil before

plant uptake and may be

lost

Impact of Weather on Soil N Supply, Soil N Losses, and Crop N Demand

Soil/Plant N

Spring Summer Fall

Potato N Uptake

Soil mineral N,Normal year

Soil mineral N,Wet spring

Amount of N fertilizer needed…

…In normalyear

…in year with wet spring

Potato Yield Response to N Fertilizer Following Fall or Spring Plowing of Alfalfa, Aberdeen 2002

325

350

375

400

425

450

0 50 100 150 200Nitrogen Rate(lbs N/acre)

Yie

ld

(cw

t/acre

)

Spring plow

Fall plow

Potato Rotation StudyRexburg, ID 2003-2005

Russet Burbank potato yields as influenced by N rates after alfalfa, wheat, or maize averaged across 2004 and 2005 seasons

83 119 164

PhosphorusSecond most critical nutrientEssential for energy transferCritical for root growthGenerally low in soil availabilityRapidly tied up by soilManagement is long-termApplication important in all soils

From Rowe, 1993

Total Potato N, P, and K Uptake

0

50

100

150

200

250

300

350

0 20 40 60 80 100

Vegetative Growth

Tuber Initiation

Tuber Bulking Maturation

K

N

P

Days After Emergence

Nu

trie

nt

Up

take

(lb

/ac)

Phosphorus and Dry Matter Accumulation

0 5 101520253035404550556065707580859095100

0

0.2

0.4

0.6

0.8

1

1.2

Days After Emergence

Acc

umul

ation

/max

imum

dry matter

P

Soil P Buffering CapacitySoil P Buffering Capacity

Depletion of solution P brings absorbed P into solution to maintain equilibrium

Rate of establishing new equilibrium depends on rate of desorption from absorbed forms and rate of diffusion (i.e., the withdrawal rate is proportional to the size of the bank)

Phosphorus Precipitation on CaCO3Phosphorus Precipitation on CaCO3

P adsorbed to CaCO3 surfaces forming ion clusters

Clusters allow for nucleation of Ca-P crystals

Common in calcareous soils of Southern Idaho

Calcite equilibrated for 10 days

Calcite equilibrated for 10 days

0 ppm P10 ppm P10 ppm P25 ppm P25 ppm P50 ppm P50 ppm P100 ppm P100 ppm P

500 ppm P500 ppm P

Ammonium PhosphatesAmmonium PhosphatesMAP (11-52-0) NH4H2PO4 3.5

DAP (18-48-0) (NH4)2HPO4 8.5

APP (10-34-0) ammonium polyphosphate

6.2

Reaction pH

P Fertilizer GranuleP Fertilizer Granule

CaHPO44

H2Oadsorption

precipitationCa2+ H3PO4

Recovery of Fertilizer PRecovery of Fertilizer PPlants recover 5 to 20%

Remainder reacts with soil components

Residual fertilizer P builds up soil P to increase future availability

Phosphorus Fertilizer ProgramPhosphorus Fertilizer ProgramAdequate P concentration in bulk soil

to maintain optimal P concentration

Starter bands to enhance early season P availability

Maintenance / building of soil P levels

Preplant Phosphorus Options Preplant Phosphorus Options

Ammonium Phosphates - liquid and dry

Avail

Humic Acids

Controlled Release P

In-Season P Sources – APP (10-34-0) and phosphoric

acid

BroadcastBroadcast BandBand

Preplant P Fertilizer Recommendations for Russet Burbank PotatoesPreplant P Fertilizer Recommendations for Russet Burbank Potatoes

0 320 360 400 440

5 240 280 320 360

10 160 200 240 280

15 80 120 160 200

20 0 40 80 120

25 0 0 0 40

30 0 0 0 0

Apply an additional 40 to 80 lb of P2O5/acre as a starter at planting for soil test P levels below 30 ppm.Add 25 lb P2O5/acre as a starter for additional 100 cwt/acre above 400 cwt/acre.

Soil Test P(0-12 inch depth)

ppm

Percent Free Lime

------------ lb P2O5/acre ----------------

0 4 8 12

Dry Matter Balance

0

0.5

1

1.5

2

0 0.1 0.2 0.3 0.4

Dry

Mat

ter

Bal

ance

(to

tal

/ tu

ber

s)

Average P in leaves (%)

Y = 0.76X – 0.7r2 = 0.67

(0.22)

Westermann and Kleinkopf, 1985

0.22% P = sufficiency level

Phosphorus FertigationPhosphorus Fertigation

Maintain petiole P concentration above 0.22% through tuber bulking

30 to 40 lb P/A in late July can increase total P uptake 4 to 5 lb/ac

Typically use APP (10-34-0) or Phosphoric acid

PotassiumUsed in large quantities by plants

Important in translocation of nutrients

Easily leached in sandy soils

Some soils naturally low

Application important in all soils

Total Potato N, P, and K Uptake

0

50

100

150

200

250

300

350

0 20 40 60 80 100

Vegetative Growth

Tuber Initiation

Tuber Bulking Maturation

K

N

P

Days After Emergence

Nu

trie

nt

Up

take

(lb

/ac)

Forms of Potassium in SoilForms of Potassium in Soil

Mineral 5,000 - 25,000 ppm

Non-exchangeable 50 - 750 ppm

Exchangeable 40-600 ppm

Solution 1-10 ppm

K Absorption by PlantsK Absorption by Plants

Primarily by diffusion and mass flow

Related to K intensity (solution K)

Diffusion : 85 - 95% of K uptake

Mass Flow : 5 - 10% of K uptake

K quantity (Q) = exchangeable K

Relationship between STKC and K DiffusionRelationship between STKC and K Diffusion

STKC, ppmSTKC, ppm

K D

iffu

sion

p

pm

/

day

K D

iffu

sion

p

pm

/

day

>

0

0.5

1

1.5

2

2.5

70 90 110 130 150

y = 0.0138x – 0.30r2 = 0.64

>

Relationship between STKC and slow-release K from soil extractsRelationship between STKC and slow-release K from soil extracts

STKC, ppmSTKC, ppm

Slo

w R

ele

ase

K

, p

pm

/ d

ay

Slo

w R

ele

ase

K

, p

pm

/ d

ay >

400

800

1200

1600

2000

0 100 200 300 400 500

175

Soil K RecommendationsSoil K Recommendations

Critical STKC for potatoes = 175 ppm

About 4.6 lb K2O/ac required to raise STKC 1 ppm per 1 foot of soil (without fixation)

Estimated K fixation 5% at 150 ppm STKC and 27% at 25 ppm STKC

Potassium fertilizer recommendations Potassium fertilizer recommendations

25 550 600 650 700

50 450 500 550 600

75 350 400 450 500

100 250 300 350 400

125 150 200 250 300

150 50 100 150 200

175 0 0 50 100

ppm ------------- lb K2O/ac -------------

(0-12 1nch) 300 400 500 600 (0-12 1nch) 300 400 500 600

Soil Test K Yield Goal (cwt/ac) Soil Test K Yield Goal (cwt/ac)

Potassium Fertilization GuidelinesPotassium Fertilization GuidelinesProbability of a K response:

loamy sand > sandy loam > loam > silt loam

Slight advantage for K2SO4 over KCl (@rates

> 200 lb K2O/A) for:specific gravitiesNo. 1’s

Potassium Fertilization GuidelinesPotassium Fertilization GuidelinesBanded K not as effective as

broadcast K K in starter band should be < 50

lb K2O/ac (salt effect)

Avoid high (>300 lb K2O/ac) spring applications

yield reductions observed with spring applications of 400-600 lb K2O/ac

higher rates should be split fall/spring

Potassium Fertilization GuidelinesPotassium Fertilization Guidelines

Preplant K more effective than applying most of the K in-season (fertigation)

Fertigation - no consistent difference between K sources (KCl, K2SO4, KTS)

Avoid large (>50 lb K2O/A) single fertigation applications

Potassium Fertilization GuidelinesPotassium Fertilization Guidelines

Use petiole testing to determine K fertigation requirements

Maintain > 7.0 - 7.5 ppm K in fourth petiole

Cut off K fertigation 30 days before vine kill to avoid reducing specific gravity

N and P Fertilizer Effects on Specific Gravity of Russet Burbank Potatoes, Aberdeen (1985)

0150

300

1.07

1.075

1.08

1.085

1.09

0

120

240

N Applied (lb N/acre)

P Applied (lb P2O5/acre)

PotassiumDeficiency Symptoms

Symptoms appear on young, full-sized leaves

Leaflets become rugose (crinkled)

Leaves take on a scorched appearance with black pigmentation and necrotic (dead tissue) edges

Potassium Deficiency Symptoms

http://www.microessentials.com/

Secondary Macronutrients

Sulfur Calcium Magnesium

SulfurImportant as a component of proteinsOften naturally availableMany sources Fertilizer by-product Water supply Organic matterSome soils inadequate

Ideally, 15 ppm or greater

SulfurDeficiency SymptomsGeneral chlorosisSimilar to nitrogen deficiency except

young leaves remain yellow over timeLeaflet yellowing is uniform and general>0.20% S in petiole - sufficient

Sulfur deficiency Symptoms

Calcium

Important for cell wall integrityAbundant in arid soils

Ideally, 300 ppm or greater Passive uptake - moderate solubilityPoor transport under cool conditionsFoliar applications not transported to tubersApplication necessary in acid soils for pH

adjustment

Calcium Deficiency SymptomsSymptoms appear on youngest leaves firstLeaflets cup upwardBrown spotting on leafletsLeaflets eventually dry up and become

brown if symptoms are severe>0.60% Ca in petiole - sufficient

Calcium Deficiency Symptoms

Magnesium

Component of chlorophyllDerived from native rocksSome soils deficient

Ideally, 100 ppm or greater Application commonly necessary in acidic

soils

MagnesiumDeficiency Symptoms

Symptoms appear first on young mature leaves

General chlorosis with veins remaining green

Leaflets near growing point remain greenInterveinal necrosis causes scorched look>0.30% Mg in petiole - sufficient

Mg Deficiency Symptoms

Micronutrients Boron Copper Iron Manganese Molybdenum Zinc

MicronutrientsEssential as activators and for enzyme

systemsAvailability affected by pHBoron naturally low in some soilsCopper often deficient in muck soilsIron, manganese, and zinc unavailable in

alkaline soils

IronDeficiency Symptoms

Growing point and young leaves become yellow or in extreme cases, white

Usually not accompanied by necrosisVeins and leaflet ends remain green> 50 ppm Fe in petiole – sufficient> 4 ppm Fe in soil - sufficient

Iron Deficiency Symptoms

http://www.microessentials.com/

ManganeseDeficiency Symptoms

General yellowing of plantLeaves cup upwardBrown spotting occurs on leaflets,

especially along larger veins and mid-ribs> 40 ppm Mn in petiole – sufficient> 6-8 ppm Mn in soil - sufficient

Manganese Deficiency Symptoms

ZincDeficiency Symptoms

Little leaf occurs, showing as small, narrow, chlorotic leaflets

Leaflets cup upwardTip-burn on leafletsLower leaves bleach and fall from plant> 20 ppm Zn in petiole – sufficient> 1.5 ppm Zn in soil - sufficient

Zinc Deficiency Symptoms

Fertility Management PlanPrior to and at plantingSoil analysisPreplant fertilizer applications

Nitrogen (partial application)25-30% on sandy soils30-40 % on sandy loam soils40-60 % on silt loams

Phosphorus (broadcast and banded)Potassium (broadcast)Micronutrients, as needed

Fertility Management PlanDuring early tuber bulking

Continue petiole testingContinue seasonal applications of NCorrect deficiencies of P, K and micros

Fertigation for P (30-40 lbs P/ac) and K (<50 lbs K/ac)

Foliar applications for Zn, Mn, and Fe

Fertility Management PlanDuring late tuber bulking

Complete seasonal N applicationsFinish by late July – early August