Improving Fertilizer Use Efficiency for Horticultural Crops University of Florida
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$# $ % & % $# $ % '
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( (
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%$ % &%
Increase fertilizer use efficiency: Low P fertilizer formula Soluble vs. Controlled-release fertilizers Fertigation Foliar fertilization “Snake oils” Other practices
Low P fertilizer formula
%$
%$
*++,-*++
*++ -*+++
700
*+++Yield (bags/ac)
600
a
a
a
500 400 300 200 100 0
0
50
100
P fertilizer rate (% of grower rate)
2200
96.4%
2000 1800
Soil P (ppm)
1600 1400 1200 1000 800 600 400 200 0
0.13%
3.47%
nonAB-DTPA extractable extractable
100% 90%
40%
20%
9
0% Exchangeable P
Al-Fe P
O rganic P
C a-Mg P
Re sidual P
Biscayne --Wetland Biscayne2 Biscayne3
10 5
4
5
6
7
)2 OH ) ( 46 (PO 0 Ca 1
9
Krome4 --Fruit grove Krome5
Ca HP O 4 2H 2O
Krome6 Pozo Blanco --Puerto Rico
O 5H 2 ) )6 O42 O4 (P (P Ca 3 H2 βCa 8 P TC
HA
8
Fraternidad Guam1 Guam2
10 4
5
6
2+
pH - 1/2pCa
7
Krome1 Vegetable field Krome2 Krome3 Chekika1 Chekika2
P OC
7
O ) 5H 2 (OH O )2 l (P 4 CaA 3 CRD
4) 3 PO F( Ca 5
6
DC PD
8
B
FA
pH2PO4- + 1/ pCa2+
Soluble P
Rockdale1 --Pineland Rockdale2 Rockdale3
P TC
10%
8
Ca HP O 4 2H 2O
O 5H 2 )6 )2 O4 O4 (P (P H2 Ca 3 βCa 8
30%
7
DC PD
HA
pH2PO4- + 1/ pCa2+
50%
6
P OC
Percentage of Total P
Soil 12 Lime Soil 16 ENP
O ) 5H 2 (OH )2 O )2 OH l (P 4 ) ( CaA 3 46 (PO CRD 0 Ca 1
60%
A
) 43 PO F( Ca 5
70%
5
Soil 7 Tomato Soil 11 Avocado
FA
80%
8
P
K
D e g re e s C e n tig ra d e
Soil and Air Temperatures:24 hr. Jan. 26 to 27.(6 pm -5 pm) 25 20 G
Typical water-soluble N and P fertilizers used in horticultural production Nitrogen Ammonium sulfate Ammonium nitrate Urea Potassium nitrate Calcium nitrate
High-volume use of controlled-release fertilizer is limited to> >turfgrass >greenhouse >nursery >landscape
Cost of materials for citrus (3 yrs ago) 3-$ 5 B
! '
C ' %
0
7
/ 0
)
" 5 B
% 7
*+6A
36 A
,6 2,
*A6*
A6
36 2*
*26 +
26 +
A6 +
26
A6 2
* 6
**6
A63 6
How does the relative COST OF FERTILIZER MATERIALS AND APPLICATION METHODS affect fertilizer selection by producers? Vegetables (3 yrs ago) Potato study: Cost of a water-soluble N fertilization program D $38 to $63 per acre. Extra cost to use a CRF program cost D $8 to $79 more than the most expensive soluble N cost. Extra cost could be offset by reduced application rate and/or providing cost-share to use CRF.
What do we know about CRF> >rates? >timing? >placement? >plant response? >leaching? >release rates as affected by temperature and moisture?
Fertigation
Fertigation:
What do we know about> >nutrient use-efficiency? >application frequency? >plant response? >leaching potential?
Fertigation improved N USE EFFICIENCY in bell pepper production. Yield at four pre-plant/fertigation N fertilizer combinations. Fert. application method Percent N applied pre-plant
Percent N applied by fertigation
Total fancy pepper yield
Total marketable pepper yield
---------------- tons/acre ----------------
0 30 70 100
100 70 30 0 P-value
4.2 4.4 3.8 2.9
9.1 9.5 8.3 6.6
0.0531
0.0006
With good water management, fertigation APPLICATION FREQUENCY doesn’t matter much. 6-year-old orange trees growing in lysimeters. Year
Relative amount of applied N that leached
N uptake efficiencyz
%
%
76
51
30
Weekly
36
58
27
Monthly
11
56
24
81
46
42
Weekly
38
62
28
Monthly
14
53
35
Fertigation treatment
Fertigations per year
1999 Every irrigation
2000 Every irrigation
8
% %
' '
%
0$ 6
)
0$
Horticultural PLANT RESPONSE to fertigation is as good or better than the response observed with well-managed dry soluble fertilization. In both cases, irrigation (and sometimes drainage) water management is critical for success.
Why was there more leaching with fertigation compared with dry soluble fertilizer application? Estimated N leached below a ridge citrus grove root zone. N rate lbs/acre
Dry soluble fertilizer
Fertigation
CRF
---------------- lbs N/acre/year ----------------
50
---
---
0.8
100
11.1
16.3
2.9
150
11.8
21.5
7.1
200
12.2
27.1
---
250
19.0
31.3
---
Study authors: This occurred “purely because of unexpected prolonged irrigation or unexpected high rainfall following certain fertigation events in both years.”
Foliar fertilization
Can FOLIAR FERTILIZER APPLICATION improve nutrient use efficiency? Tree crops: Possibly Foliar uptake of urea can be 50% efficient; it has enhanced flowering and yield. Phosphite is recognized as a P source; it has increased flowering, fruiting, and lbs solids.
Vegetables: No? Leaves cannot absorb enough N/P to correct a deficiency. Leaf burn is likely.
Improve fertilizer use efficiency by: Develop a nutrient management plan Do a fertilizer trial by yourself Use appropriate application equipment. Use appropriate fertilizer sources and formulations Add organic matter to the soil whenever possible. Split fertilizer applications. Try to wet only the root zone when irrigating.
