Foliar nutrition involves applying liquid fertilizers directly to plant leaves. Nutrients are absorbed through the leaf cuticle. [1] Foliar nutrition can improve macadamia tree nut yields, restore tree health, and improve canopy growth after pruning. [2] The timing and combination of nutrients applied is important for maximum efficacy. Nutrients should be applied at different crop stages from spring flush to post-harvest. [3] Foliar applications can complement soil-applied fertilizers by improving nutrient uptake from the soil.

1. Foliar Nutrition in Macadamia Tree Nut Production
International Macadamia Symposium - Brisbane
September 2012
Mathur,
Dr. Deepak Mathur, Ph.D.
Director: Technical Services, Agrichem
4 Hovey Road, Yatala, Qld 4207, Australia
Yatala,

2. Production constraints
Limiting Nutrient
General aspects of foliar nutrition
1. Stomatal role
2. Pathways
3. Dynamics & Efficiency
4. Stage specific nutrition
Foliar nutrition in Macadamia

3. Global Constraints: Agricultural
Production Systems
•Limited irrigation water supplies
•Nutrient use efficiency
•Diminishing Micronutrient pool
•Rising salinity
•Problem soils
•Water Quality issues
•Environmental issues
•Global food shortage
FAO: WE MUST DOUBLE FOOD
PRODUCTION BY 2030

4. • Justus von Liebig
•His laws reformed agriculture
“Whichever nutrient is in the
least amount relative to the
required amount, will determine
the yield of a plant”

5. Foliar feeding is a technique of feeding plants
by applying liquid fertilizer directly to their
leaves. Nutrients are absorbed through the
leaf cuticle.
The cuticle is the outermost layer of the leaf
that consists of epicuticular wax and is
negatively charged due to the presence of
polygalactouronic acid

6. Improves Yield
Restores tree health
Improves canopy growth after pruning
Foliar-applied calcium, boron, copper, and zinc, used alone or in
combination, have been shown to enhance acclimation or repair of stress-
injured tissues.
Further understanding of the oxidative stress may offer new approaches
for the use of foliar-applied nutrients on perennial fruit plants
Foliar applied nutrients create a negative osmotic pressure within the leaf
tissues that triggers roots to absorb more water from soil. As a result the
roots also absorb soil applied nutrients that moves en masse with water.
Hence foliar nutrition also improves the efficacy of soil applied nutrients
nutrients.
Maximum impact of foliar sprays can be seen under:
Adverse Soil Conditions
Low Nutrient Availability in soil through adverse interactions such as
calcium and phosphorus

7. Stomata, the tiny leaf openings on the upper and
lower surfaces of the leaf, do not play any significant
role in the absorption of foliar nutrients
The mechanical force of pushing water vapor out
through the process of transpiration restricts the
entry of nutrients through stomata
The night time foliar nutrient uptake exceeds the
day time absorption through leaves as demonstrated
by radio isotope studies
Plants are also able to absorb nutrients through their
bark and bark does not contain stomata.

8. Foliar nutrition application goal:
◦ Increase duration of leaf wetness to increase availability of elements
◦ Increase cation movement through leaf cuticle
Increased Wetness
Movement
Movement
Movement
Movement
Increased
Increased
Increased
Increased
Mn Mn Mn Cation
Cation
Cation
Cation
Mn Mn Mn Mn Mn Mn
Without Surfactant With Surfactant

9. Movement
Coverage, Limits at
Cuticle & Cell to Cell in
Deposition, the
Stomates Movement Conducting
Wetting Membrane
Tissues

10. E= Stage x Time x Combination x Rates
Where, E is the efficacy of spray product
S is the crop stage
T is the time of the day
C is compatibility of nutrients
R is the rate of application
Droplet size and distribution
Surfactants use
Maximum impact
Nutrient is deficient
Low soil temperature
Decreased root activity
Caution: Do not spray a water stressed crop

11. Spring Flush Tissue test and then apply NPK+ TE
product (Fe)
3 weeks Pre-Flowering: N, B, Ca, Mg, Zn
No Foliar Sprays at Flowering: Flower drop
Tissue test recommended: Post flowering
Nut set- Ca, B, Zn, Mg+ High auxin/cyt kelp
Early Nut fill- K, B, Mg, Fe
Late nut fill- K, Mg, Ca
Tissue test after 85-90% pick
Post harvest- N, Ca, Mg, B, K, Fe
Foliar compliments soil applied ferts.

12. 4Kg±0.06/tree 5.5Kg±0.07/tree

15. VARIETY 816 VARIETY 741 Optimum
Tissue test Control Foliar Treated Control Foliar Treated Reference
N % Kjel 1.2 1.7 1.1 1.5 1.4-1.7
P% 0.10 0.15 0.11 0.13 0.07-0.1
K% 0.68 0.79 0.70 0.73 0.4-0.8
S% 0.16 0.18 0.12 0.16 0.15-0.25
Ca % 0.3 0.36 0.44 0.49 0.6-0.9
Mg % 0.09 0.09 0.13 0.12 0.08-0.12
Zn ppm 8 13 10 18 6.0-50.0
Fe 11 33 20 29 30-200
Mn 40 52 70 89 47-1850
Cu 3.1 4.2 3 3.5 4.5-20
B 18 28 17 25 40-80

16. Thank you, Question time!