Irrigation A key component of high quality Farming Systems Research division Ian Goodwin, Senior research scientist
Weather Conditions (sunlight, wind, humidity and temperature) Orchard water balance CROP WATER USE Tree Architecture Planting Arrangement Leaf Area Density Understorey Water Use WATER SUPPLY Microjet Drip Wetting Pattern Soil Type Root Distribution Weather Conditions (rainfall)
Crop Water Use > Water Supply Water Stress
The effects of water stress Yield 100 Yield potential (%) 80 60 40 Yield penalty Drainage losses 20 0 0 0.5 1 1.5 2 2.5 Water Crop supply water relative supply relative to crop to water CWRuse
The effects of water stress Fruit size Fruit volume (cm3) 180 160 140 120 100 80 60 38% 50% 74% 100% 162% Royal Gala 40 20 0 02/10 22/10 11/11 01/12 21/12 10/01 30/01 19/02 Date
The effects of water stress Total soluble solids Royal Gala Cripps Pink Total soluble solids ( o Brix) 17 16 15 14 13 LSD (P=0.05) 2008/09 2009/10 2010/11 2011/12 Total soluble solids ( o Brix) 18 17 16 15 14 LSD (P=0.05) 2008/09 2009/10 2010/11 2011/12 12 38% 50% 74% 100% 162% Treatment 13 38% 50% 74% 100% 162% Treatment Water stress Water stress
The effects of water stress Antioxidants Royal Gala ORAC (micromol TE/100g FW) 2500 2000 1500 LSD (P=0.05) 2008/09 2009/10 2010/11 Total polyphenols (mg GAE/g FW) 1.6 1.5 1.4 1.3 1.2 1.1 LSD (P=0.05) 2008/09 2009/10 2010/11 1000 38% 50% 74% 100% 162% 1.0 38% 50% 74% 100% 162% Treatment Treatment Water stress Water stress
The effects of water stress Cracking Fruit number per tree 500 400 300 200 100 Total fruit Split fruit Cripps Pink 0 0% 50% 100% 150% 200% Treatment (% of grower practice)
The effects of water stress Sunburn Cripps Pink 800 Fruit number per tree 600 400 200 Total fruit Sunburned fruit Sunburn necrosis 0 0% 50% 100% 150% 200% Treatment (% of grower practice)
The effects of water stress Fruit temperature 50 40 Temperature (deg C) 30 20 10 Air temperature Fruit temperature - 38 % West Fruit temperature - 162 % West 0 22/2/12 23/2/12 24/2/12 25/2/12 26/2/12 Date
Weather Conditions (sunlight, wind, humidity and temperature) Orchard water balance CROP WATER USE Tree Architecture Planting Arrangement Leaf Area Density Understorey Water Use WATER SUPPLY Microjet Drip Wetting Pattern Soil Type Root Distribution
Crop water use Orchard water use = Tree water use + Understorey water use
Crop water use Tree water use = 1.3 x EAS x ET o Understorey water use = K e x ET o ET o is reference crop evapotranspiration (water use of grass) EAS is the effective area of shade (convert grass to tree water use) K e is the understorey (soil evaporation) coefficient (convert grass to understorey water use)
Reference crop evapotranspiration (ET o ) solar radiation, wind speed, humidity, temperature BOM - http://www.bom.gov.au/
Tree water use Effective area of shade (EAS) - the fraction of the orchard floor shaded by the tree - = Shade (am) + Shade (midday) + Shade (pm) 3 i.e. 10 am, 1:30 pm and 5 pm summer time http://new.dpi.vic.gov.au/agriculture/horticulture/fruit-nuts/orchard-management/determiningeffective-area-of-shade-in-orchards-and-vineyards-to-estimate-crop-water-requirement
EAS tree size training system planting arrangement leaf area density
EAS
EAS Row width = 4.5 m Gap fraction of shade = 0.75 Length of shade = 3.5 m Percent shade = Length of shade x Gap fraction of shade Row spacing = 3.5 m x 0.75 4.5 m x 100 = 58 %
Understorey water use Irrigation system Microjet K e = 0.2 Drip K e = 0.1
Orchard water use Example Microjet irrigated apple orchard ET o = 7 mm EAS = 40 % Understorey coefficient = 0.2 Tree water use = 1.3 x 40 % x 7 = 3.6 mm Understorey water use = 0.2 x 7 = 1.4 mm Orchard water use = 3.6 + 1.4 = 5.0 mm
Weather Conditions (sunlight, wind, humidity and temperature) Orchard water balance CROP WATER USE Tree Architecture Planting Arrangement Leaf Area Density Understorey Water Use WATER SUPPLY Microjet Drip Wetting Pattern Soil Type Root Distribution Weather Conditions (rainfall)
Available soil water Unavailable Available Soil Water Unavailable Drainage Readily Available Water (RAW) Deficit Available Water (DAW) Minimally Available Dry Saturation Field Capacity Wilting Point Oven dry soil 0 2 50 200 1500 infinity Soil Water Tension (kpa) Readily Available Water (RAW) GV topsoil = 8 % GV subsoil = 6 % Sandy soil = 4 %
Available soil water (1) Total root-zone Readily Available Water When to initiate irrigation - Root distribution - Soil type (i.e. RAW) Example: Fibrous root-zone depth = 400 mm Lateral root distribution = 75 % RAW = 8 % Total root-zone RAW = 400 x 75 % x 8 % = 24 mm
Available soil water (2) Wetting pattern Readily Available Water Optimum irrigation run time (hour) - Fibrous root-zone depth (400 mm) - Emitter rate and coverage - Soil type (i.e. RAW) Soil type Drip Microjet 1.6 l/h 2.3 l/h 25 l/h 35 l/h (r = 1.4 m) (r = 1.8 m) Sandy clay loam 7 h 5 h 5 h 4 h Clay loam 8 h 6 h 6 h 5 h Sand 3 h 2 h 3 h 3 h
Water budgeting Apple Orchard Water Budget Month Long-term Effective Basal Crop Soil Evaporation Orchard Average Soil Stress Irrigation Average ETo Area of Shade Coefficient Coefficient Water Use Rainfall Reserve Coefficient Requirement (mm) (%) (mm) (mm) (mm) (mm) September 69 20 0.3 0.7 66 110 42 1.0 0 October 99 30 0.4 0.5 88 64 2 1.0 0 November 128 45 0.6 0.2 100 45 0 1.0 65 December 156 45 0.6 0.2 122 27 0 1.0 102 January 165 45 0.6 0.2 130 18 0 1.0 116 February 143 45 0.6 0.2 112 17 0 1.0 100 March 119 45 0.6 0.2 94 28 0 0.7 51 April 76 40 0.5 0.2 55 51 0 0.7 12 May 50 30 0.4 0.2 29 112 42 0.7 0 TOTAL (mm) 797 445 TOTAL (ML/ha) 8.0 4.4 Effective Rainfall (%) 75 Soil Water Reserve in Root-zone Layer Root-zone extent Soil RAW or DAW Soil Reserve Depth (mm) Lateral (%) Texture (%) (mm) 1 300 100 sandy loam 6 18 2 300 100 clay loam 8 24 3 TOTAL 600 42 180 ETo 160 Water Use 140 Irrigation 120 100 80 60 40 20 0
PIPS-ET Calculator
Irrigation scheduling plan Irrigation Scheduling Plan Location Manjimup Tree Spacing (m) 2 Block south east Row Spacing (m) 5 Variety Royal Gala Emitter Output (litre/hour) 30 Clone Emitter Spacing (m) 2 Rootstock Laterals per Row 1 Month Irrigation Irrigation Long-term Basal Soil Stress Tree x Daily Irrigation Run Time Amount Average Crop Evaporation Coefficient Row Water Interval ETo Coefficient Coefficient Spacing Use (hour) (litre/tree) (mm/day) (square m) (litre/tree) (day) September 4 120 2.3 0.3 0.2 1.0 10 11 11 October 4 120 3.2 0.4 0.2 1.0 10 19 6 November 4 120 4.3 0.6 0.2 1.0 10 33 4 December 4 120 5.0 0.6 0.2 1.0 10 40 3 January 4 120 5.3 0.6 0.2 1.0 10 42 3 February 4 120 5.1 0.6 0.2 1.0 10 40 3 March 4 120 3.8 0.6 0.2 0.7 10 21 6 April 4 120 2.5 0.5 0.2 0.7 10 13 9 May 4 120 1.6 0.4 0.2 0.7 10 7 18
Real-time irrigation scheduling
Soil moisture monitoring Fine tune: Irrigation run time Crop coefficient (i.e. orchard water use) When to irrigate after rainfall
Soil moisture monitoring
Soil moisture monitoring sensors www.irrigationfutures.org.au/imagesdb/news/soilwatermonitoring2ed.pdf
Satellite remote sensing Orchard water use 1.2 1.0 0.8 ET/ETR 0.6 0.4 0.2 JAN 0.0 0.0 0.2 0.4 0.6 0.8 1.0 NDVI Source: O Connell, PhD thesis
Orchard stress monitoring
Orchard water use and stress monitoring
Thank you ian.goodwin@depi.vic.gov.au Questions