Transcript Fertilizer Sources-Proper Selection and Management

Fertilizer Sources: Proper Selection and
Management
Dale F. Leikam
Associate Professor
Kansas State University
T. Scott Murrell
Northcentral Director
Potash & Phosphate Institute
2006
Questions to be addressed: N sources for corn
• How does corn take up and use nitrate?
• How does corn take up and use ammonium?
• Is there an optimum NH4+:NO3- ratio?
• How do N forms react prior to plant uptake?
• How do these reactions impact phosphorus
management?
Corn root: horizontal cross section
Casparian strip
Stele
Endodermis
Root hair
Xylem
Russell, 1977
Phloem
Pericycle
Cortex
Epidermis
Zea mays root cross-section, mature root
Corn root cross section
Cell wall
Plasmodesmata
Cytoplasm
Vacuole
Russell, 1977
Zea mays root cross-section, mature root
Symplasmic pathway: transport of nutrients through
the cytoplasm
To xylem
Marschner, 2002
From root
epidermis
and cortex
Zea mays root cross-section, mature root
Getting nutrients into the symplasmic pathway
Nitrate, phosphate, chloride:
co-transport via a
proton pump
Proton-ATPase pump
(requires energy - ATP)
Moves H+ “uphill” against
the electrical potential gradient and
the chemical potential gradient (pH)
ATP
H+
H+
Anion
pH 7.3-7.6
pH 5.5
-120 to -180 mV
Vacuole
Cytoplasm
Tonoplast
Marschner, 2002
Plasma
membrane
Cell wall
Getting nutrients into the symplasmic pathway
Cations (except K)
Uniport
Uniport:
“downhill” of electrical potential gradient,
but energy is still needed
to maintain the gradients
Cation
-120 to -180 mV
Vacuole
Cytoplasm
Tonoplast
Marschner, 2002
Plasma
membrane
Cell wall
A comparison of ammonium and nitrate assimilation
Nitrogen form
Characteristic
NO3-
NH4+
Directly stored in vacuoles?
yes
no
Form stored
NO3-
amino acids, amides
Energy costs of storage
lower
higher
Assimilation mechanism
NO3- reduction
Incorporated into
amino acids, amides
Mechanism products
NH3, OH-
Amino acids,
amides, H+
Assimilated by roots?
yes
yes
Assimilated by shoots?
yes
no
Net C fixation by roots, (NO3-) basis
1x
5x (corn)
Marschner, 2002
Dry weight (g plant-1)
Early corn growth and ammonium/nitrate ratios
Total
concentration
(mM)
5.0
1.0
5
4
3
2
0.2
1
0
100
0
75
25
50
50
25
75
0 NH4+
100 NO3-
Proportion of N form
Marschner, 2002
Ammonium and nitrate: rhizosphere pH differences
pH
Acid
NH4+
NO3-
H+
OHor HCO3-
Basic
Marschner, 2002
Wheat – 2wks
Scale
Rōmheld
NO3-N
Corn – 8 wks old
NH4-N
NO3-N
200 kg N per ha
NH4-N
Effect of Nitrogen form on Rhizosphere pH
1:1
8.0
NO3- Soy
Rhizosphere pH
7.5
NO3- Corn
7.0
6.5
6.0
5.5
5.0
NH4+ Soy
4.5
NH4+ Corn
4.0
4.0
4.5
5.0
5.5
6.0
6.5
Bulk soil pH
Riley and Barber, 1971; Soon and Miller, 1977
7.0
7.5
8.0
Why is there a need for both ammonium and nitrate?
• Rhizosphere pH control
• If rhizosphere pH drops too much, ammonium uptake becomes
restricted, favoring nitrate uptake
• Reverse occurs if pH increases too much from nitrate uptake
• Carbon allocation and energy regulation
• Less photosynthate is needed for nitrate assimilation
• Nitrate has lower energy storage costs since it can be stored
“as is”
• So the presence of both ions helps the plant regulate rhizosphere
pH, energy expenditures, and carbon allocation
• 11 day old corn
• Ammonium
source reduced
rhizosphere pH
and increased P
uptake
Total P uptake, mg P (g DM)-1
Rhizosphere pH affects P uptake by corn
Oneida L
6
Buford SiL
5
4
Wendigo SL
3
MCP + CaCl2
2
MCP + Ca(NO3)2
MCP + (NH4)2SO4
1
0
3
4
5
6
7
Rhizosphere pH
Soon and Miller, 1977
8
9
Starter fertilizer: NH4+ and P should be placed together
Percent of the plant P
coming from the band
60
20-40 lb P/acre
20-40 lb P/acre + 10 lb N, mixed
20-40 lb P/acre + 10 lb N, separate
40
Occurs regardless
of P soil test level
20
0
0
400
800
1200
1600
2000
Phosphate added to bulk soil, lb P2O5/acre
Miller and Ohlrogge, 1958
Common phosphate fertilizers with ammonium
• Monoammonium phosphate (MAP)
• NH4H2PO4
• pH of 0.1M solution is 4.0
• H2PO4- ↔ HPO42- + H+
• Diammonium phosphate (DAP)
• (NH4)2HPO4
• pH of 0.1M solution is 7.8
• HPO42- ↔ H2PO4- + OH-
• Ammonium polyphosphate (APP)
• pH 6.0 – 6.5
• Hydrolysis reaction
Photos courtesy of Agrium
Sauchelli, 1965
Nitrification: Converts ammonium to nitrate
Step 1: conversion to nitrite by the Nitrosomonas bacteria
2NH4+ + 3O2 → 2NO2- + 4H+
Step 2: conversion to nitrate by the Nitrobacter bacteria
2NO2- + O2 → 2NO3Important components of the reaction:
• Requires oxygen
• Reaction is acid-forming
Havlin et al., 2005
Nitrosomonas (Natl. Inst. Res. Environ.)
Reaction of anhydrous ammonia
Ammonia hydrolysis (splits water):
NH3 + H2O
NH4+ + OHNitrification
• Reaction of ammonia with water is base-forming
• Reaction is reversible at a higher pH
• Nitrification can acidify the band that was initially higher in
pH
Sauchelli, 1964
Measured pH changes after ammonia injection
1 day
3 weeks
10 weeks
3.5 in.
< 5.1
pH
scale
5.1 – 6.0
6.1 – 7.0
7.1 – 8.0
> 8.0
Cochran, 1975
Laboratory experiment:
Walla Walla SiL
Initial pH = 5.5
CEC = 17 meq/100g
N rate was equivalent to
107 lb N/acre at 20 in. spacing
Acidification patterns in soil after knifed ammonia
(ridge-slot plant system)
30 in.
30 in.
0
10
2 months after an early May application
0
10
14 months after an early May application
Robbins and Voss, 1989
Webster clay loam
Implications of soil acidification after ammonia applications
In reduced tillage systems with knifed ammonia
applications, apply in the same zones each time
• The pH increases help reverse acidity resulting
from nitrification from the previous applications
• Keeps subsurface acidity from spreading to other
areas
Robbins and Voss, 1989
Effects of ammonia concentration on nitrification
pH right after application
9
8
250
pH after 14 days
200
6
5
150
4
100
[NO3-] after 14 days
3
2
50
1
0
0
0
200
400
600
Ammonia (NH3-N ppm)
Eno et al., 1955
7
800
pH
Nitrate N (ppm)
300
Recommendations based on ammonia reactions
• Ammonia is the preferred source for:
• Fall applications (sustained soil temp. below 50oF)
• Spring pre-plant applications on sandy soils
• Ammonia should be injected 6-10 in. deep on
friable, moist soil to avoid:
• Volatilization losses
• Injury to seedlings
Reaction of urea
Urea hydrolysis at pH 6.5 – 8.0
urease
CO(NH2)2 + H+ + 2H2O → 2NH4+ + HCO3Urea hydrolysis at pH < 6.5
urease
CO(NH2)2 + 2H+ + 2H2O → 2NH4+ + H2CO3
• Acid-consuming
• pH will not increase above 9.3
Koelliker and Kissel, 1988
Volatilization of ammonia
The reaction
NH4 ↔ NH3 + H+ is driven by:
• Difference in NH3 activity between where the fertilizer was
applied and the surrounding air (windy conditions)
• Higher pH
• Higher temperature
• Lower CEC
(maintains a higher solution NH4 concentration)
• Loss of CO2, which causes the pH to increase
• Contact with crop residues, which contain urease
Koelliker and Kissel, 1988
Phosphorus form affects urea volatilization
Ammonia loss
Treatment
clay, pH 5.2
silty clay loam, pH 6.0
(% of urea N)
Urea
4.7
9.8
Urea + TSP
1.8
4.9
Urea + MAP
4.2
4.1
Urea + DAP
12.8
14.2
Total N was kept constant at 117 lb N/acre
P rate was kept constant at 132 lb P2O5/acre
Fan and Mackenzie, 1993
Practical suggestions for urea use
• Avoid using as a preplant application on sandy soils
• Avoid contact with the seed
• Within 2 days:
• Incorporate to a depth of 2 to 4 inches or
• Receive or apply 0.25 to 0.5 in. of precipitation
• Other considerations for no-till
• Consider surface bands to reduce contact with urease
• If also applying P, band MAP or TSP with the urea at the
surface
Summary
• N nutrition affects the pH of the soil surrounding the root
and P uptake. Ammonium forms should be placed with P.
• When ammonia is formed, nitrification can be delayed
• In reduced tillage systems, acidification from nitrification
needs to be controlled, possibly through the use of N
fertilizers that are initially base-forming, repetitively
banded in the same location
• Phosphorus can be a good product to co-apply with
ammonium banded near the seed
• Phosphorus can be a good product to co-apply with urea
banded at the surface
References
Anghinoni, I. and S.A. Barber. 1980b. Predicting the most efficient phosphorus placement for corn. Soil Sci. Soc. Am. J. 44:1016-1020.
Barber, S.A. 1984. Soil nutrient bioavailability: A mechanistic approach. Wiley Interscience, New York, NY.
Barber, S.A. 1978. Growth and nutrient uptake of soybean roots under field conditions. Agron. J. 70:457-461.
Cochran, V.L., F.E. Koehler, and R.I. Papendick. 1975. Straw placement: Its effect on nitrification of anhydrous ammonia. Agron. J. 67:537-540.
Edwards, J.H. and S.A. Barber. 1976. Phosphorus uptake rate of soybean roots as influenced by plant age, root trimming, and solution P concentration. Agron.
J. 68:973-975.
Eno, C.F., W.G. Blue, and J.M. Good, Jr. 1955. The effect of anhydrous ammonia on nematodes, fungi, bacteria, and nitrification in some Florida soils. Agron. J.
19:55-58.
Fan, M.X. and A.F. Mackenzie. 1993. Urea and phosphate interactions in fertilizer microsites: Ammonia volatilization and pH changes. Soil Sci. Soc. Am. J.
57:839-845.
Havlin, J.L., J.D. Beaton, S.L. Tisdale, and W.L. Nelson. 2005. Soil fertility and fertilizers: An introduction to nutrient management. 7th ed. Pearson Prentice Hall,
Upper Saddle River, NJ.
Koelliker, J.K. and D.E. Kissel. 1988. Chemical equilibria affecting ammonia volatilization. p.37-52. In B.R. Bock and D.E. Kissel (ed.) Ammonia volatilization
from urea fertilizers. Bull. Y-206. Natl. Fert. Development Center, TVA, Muscle Shoals, AL.
Marschner, H.M. 2002. Mineral nutrition of higher plants. 2nd ed. Academic Press, New York, NY.
Mengel, D.B. and S.A. Barber. 1974. Rate of nutrient uptake per unit of corn root under field conditions. Agron. J. 66:399-402. Borkert, C.M. and S.A. Barber.
1985b. Predicting the most efficient phosphorus placement for soybeans. Soil Sci. Soc. Am. J. 49:901-904.
Miller, H.H. and A.J. Ohlrogge. 1958. Principles of nutrient uptake from fertilizer bands. I. Effect of placement of nitrogen fertilizer on the uptake of band-placed
phosphorus at different soil phosphorus levels. Agron. J. 50:95-97.
Riley, D. and S.A. Barber. 1971. Effect of ammonium and nitrate fertilization on phosphorus uptake as related to root-induced pH changes at the root-soil
interface. Soil Sci. Soc. Am. Proc. 35:301-306.
Robbins, S.G. and R.D. Voss. 1989. Acidic zones from ammonia application in conservation tillage systems. Soil Sci. Soc. Am. J. 53:1256-1263.
Russell, R.S. 1977. Plant root systems: Their function and interaction with the soil. McGraw-Hill, New York, NY.
Sauchelli, V. 1965. Phosphates in agriculture. Reinhold Publishing Co., New York, NY.
Sauchelli, V. 1964. Nitrogen: Chemical and physical properties. p.10-17. In V. Sauchelli (ed.) Fertilizer nitrogen: It’s chemistry and technology. ACS Monograph
Ser. 161. Reinhold Publishing Co., New York, NY.
Soon, Y.K. and M.H. Miller. 1977. Changes in the rhizosphere due to NH4+ and NO3- fertilization and phosphorus uptake by corn seedlings (Zea mays L.). Soil
Sci. Soc. Am. J. 41:77-80.
Corn root: longitudinal cross section
Xylem
transports ions and
water to other
areas in the plant
Maturation
zone
Phloem
transports products of
photosynthesis to the roots
Elongation
zone
Endodermis
Encases the stele
and acts as a barrier
Meristematic
zone
Root cap
cells ahead of the
apical meristem
Mucigel
Nutrient influx by roots
Ions are not simply
absorbed according to their
ratios in solution
•
Ions with this characteristic
influx pattern require
energy to be absorbed
• H2PO4-, HPO42-, NO3•
•
K +,
NH4+
Maximum influx is reached
at higher solution
concentrations (Imax)
22-23 day old soybean roots
Influx, 10-14 lb P2O5 / (in s)
•
3.0
Imax
2.5
2.0
1.5
1.0
0.5
0.0
-0.5
0
1
2
3
4
Solution P, 10-6 lb P2O5/gal
Barber, 1984; Edwards and Barber, 1976
5
Relative dry matter yield (%)
10-3 lb P2O5 per pot
100
3.6
75
0.9
50
Corn
25
Soybean
0
0
20
40
60
80
100
Fertilized soil fraction (%)
Anghinoni and Barber, 1980; Borkert and Barber, 1985b
Influx, 10-5 lb P2O5 / (in. day)
P influx varies with plant age: The case for starter
5
Corn
4
Corn can take in P
at a high rate early
(per unit of root)
but not later
3
2
1
Soybean
0
0
20
40
-1
Barber, 1978; Mengel and Barber, 1974
60
80
Plant age, days
100
120