fertility management. irrigated potato production
TRANSCRIPT
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