A presentation delivered Upul Gunnawardena (Select Harvests) to the Soil Science Australia Workshop on salinity, sodicity and soil management under irrigated horticulture on the 19 Sept 2019 at Robinvale, Victoria.

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1
Nitrogen Management in
Australian Almond and
related issues
Upul Gunawardena
Technical Officer, Select Harvests Ltd
Central Region

2. 2
Hull Rot caused by fungi
Rhizopus stolonifer
Main factors for Hull Rot
• High Humidity
• High NO3
- in the
canopy
Hull Split in Early –mid January

3. 3
Significant %
Almond crop
losses due to
Pests $$$

4. DECIPHER © 2019
Soil Acidification Late Nitrification Hull Rot Pest
pH 2010 pH 2019 pH 2019 < 4.5

5. 5
15-20cm deep
root zone
50 cm diameter
root zone
80-100 cm deep
wet zone
Nutrient Different sources
N AN25, UAN, MAP, KNO3,
Ca(NO3)2
P MAP
K KNO3 & K2SO4
Ca Ca(NO3)2
Mg MgSO4
Monthly fertigation
Month N P K
July 6 17
Aug 50 15 50
Sept 66 9 52
Oct 50 75
Nov
Dec
Jan
Feb 12 2 15
March 36 7 45

6. 6
Late Nitrification – could be the main reason for
significantly high Hull rot level
High Nitrate level in the
root zone during the Hull
split period is one of the
main contributor for Hull
Rot

7. 7

8. 8
Different Almond
growing soils
Mallee soils Riverland Soils Hillston Soil
Soil pH (CaCl2) 6.0-5.5 7.0-7.5 7.0-8.0
CEC 2.0-4.0 10-15 27-35
EC (ds/m) 0.02-0.05 0.1-0.2 0.2-0.5
OC% <0.5% 0.5-1.0% 0.6-1.0
Cowell P 15-30ppm 20-40 30-50
Cowell K 80-120ppm 200-400 400-700
Ca:Mg ratio 1.5-2.5 4-7 2-3
Mg:K ratio 1.5-2.0 1.5-2.5 1-1.5

9. The Physiology of Nutrient uptake
Mass Flow
NO3
-, K, Mg,
S, B, Cu, Mn,
Zn, Mo
Diffusion and
Active uptake
K+, Ca+2, P, NH4
+
Nutrient Mass Flow Diffusion Ion Exchange Active Root
Uptake
Nitrogen (NO3
-) X
Nitrogen
(NH4
+) X
X
Phosphorus X
Potassium X X
Calcium X
Magnesium X
Sulfur X
Boron X
Copper X
Iron X
Manganese X
Zinc X
Molybdenum X
Open Hydroponic
system

10. 10
Study done by
Franz Niederholzer
University of California
On Winter banding of fertiliser
Soil
Solution
Compost

11. 11
Compost Application 2018-19 season –Surface spreading

12. 12
Technology to apply
Composted BioAsh into the
Root Zone

13. 13
Approx: 10 cm
Approx: 5
cm Dia
Technology to apply
Composted BioAsh into
the Root Zone

14. 14
Almond Hull Ash = BioAsh –Rich source
of K
Wet Ash
• 35-50% K2O
• 1.5% P
• 5% Ca
• 1.2 Mg
• 3% C
• 0.5% Fe
• 0.5% N
Fly Ash
• 70% K2O
• 1.4% P
• 6% Ca
• 1.8 Mg
• 6% Si
• 1.8% Fe
• 2% Cl

15. 15
NPK Winter Banding
N Plant Uptake
(255 units) (Mass flow/Active root uptake)
NO3
-/NH4
+
(Nitrification) Composted
KNO3 Bioash
AN25
UAN/Urea (35 N units)
(220 N units)

16. 16
Sustainable Recycling method of Almond Waste
Harvesting and processing
Composted
BioAsh
High K
Compost
Replace175Kunits
($510/Ha)
Replace100Kunits
($295/Ha)

17. 17
Composted BioAsh Vs Chicken
Manure
Chicken Manure Composted BioAsh
Total Nitrogen (%) 2.98 0.41
Carbon/Nitrogen Ratio 7.3 16
Estimated Organic Matter (% OM) 21.80 17.1
Total Calcium (%) 3.01 3.46
Total Magnesium (%) 0.78 0.71
Total Potassium (%) 2.66 5.00
Total Sodium (%) 0.58 0.16
Total Sulphur (%) 0.56 0.60
Total Phosphorus (%) 1.66 0.60
Total Zinc (mg/kg) 572 98.2
Total Manganese (mg/kg) 617 174
Total Iron (mg/kg) 2,000 7,092
Total Copper (mg/kg) 171.0 28.1
Total Boron (mg/kg) 61 250
Total Molybdenum (mg/kg) 11.00 <1
Cost/Ha $500 (5T/Ha) $450 (4.5T/Ha)
High Risk of Salmonella, Listeria, E
Coli …..
Zero risk of Pathogenic Bacteria

18. 18
At the Farm we will be discussing
a) Collaborated trial..
• Composted BioAsh into Soil re-structuring (soil pH, Cowell P, Cowell K
etc.., Humates, Soil Microbes, VAM, etc..) –(CSIRO)
• Winter Banding N(PK)- Composted BioAsh is delivering
14% N units; and investigating on Late Nitrification and subsequent Hull Rot
outbreak - (Ag Victoria Pathology team)
• Winter Banding of K- High Potash Composted BioAsh will be testing to
replace 100K units (SOP), and 75K units Pot Nitrate
b) Soil acidification
c) Depletion of Soil Cowell K
d) The effect of winter banding on root biology