Outline of todays discussion WUE o Total amount per crop o Timing of water applications o Understanding the critical stages of crops o Irrigation scheduling Prioritising watering when water in short supply Rotations (water profile)
Comments / Questions?
Depends on type of crop Crop water use changes with the stage of growth Evapotranspiration is the term used to describe the combined losses by evaporation and transpiration (plant water use). When a crop is actively growing the majority of water use is transpiration.
Solar radiation 1. Humidity 2. Wind speed 3. Temperature 4.
The stage of growth of the crop 1. The depth of the plant/ crop root system 2. The field capacity of the soil 3. The amount should fill the rooting zone and no more.
The area of transpiring surface 1. The rate of transpiration 2. The rate of evaporation from the soil 3. The field capacity of the soil 4.
(mm of water per 1 metre depth of soil) Sand 30 Loamy sand 40 Sandy loam 50 Sandy loam with OM 80 Loam 90 Clay 40 Well structured clay 70
Crop Irrigation Depth (mm) Irrigation (ML/ha) Potatoes 300 – 400 3.5 – 6.0 Peas 100 – 200 1.0- 2.0 Poppies 150 – 300 1.5 – 2.5 Green Beans 200 2 – 2.5 Pyrethrum 100 – 150 1 – 1.5 Carrots 350 3.5 Onions 350 – 400 3.5 – 4.0 Broccoli 200 – 250 2.0 – 4.0 Lucerne 350 – 550 3.5 – 5.5 Pasture 350 - 550 3.5 – 5.5
Fe S Mg Zn Mn Cu Mo N “Law K Ca B of th of the minimu mum” m”
Plant Insects Weeds Tiller density Variety density Radiatio Sow lodge n date frost “Law Nutrition water Diseases -log of th of the Environmental minimu mum” m”
GSR = 523 m = 523 mm 90 ll (mm) 80 70 ly rainfall ( 60 50 40 Monthly r 30 20 10 0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Attainabl tainable grain in yield d (Hag Hagley) = (water u use se – ET) x x WU WUE = (525 = (525 + 50 + 50 – 125) x 125) x 20 20 = 450 = 450 x 20 20 = = 9000 9000 k kg/ha
GSR = 459 m = 459 mm 90 80 ll (mm) 70 ly rainfall ( 60 50 40 Monthly r 30 20 10 0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Attainabl tainable grain in yield d (Cre ressy) = (water u use se – ET) x x WU WUE = (450 = (450 + 25 + 25 – 125) x 125) x 20 20 = 350 = 350 x 20 20 = = 7000 7000 k kg/ha
ear ars/pla lant plants/ s/m 2 spikele lets/ear grai ains/spikele let grai ain w weight
Sadras and McDonald, 2012
15 15 t/ha - irrig igat ated d 6X 6X @ @ 40 m 40 mm ie ie 240m 40mm - GS GSR = = 505 m 505 mm Yi Yield - 40% 40% higher o r over 4 r 4 yr yrs Ears/m s/m2 - no dif difference Grain ins/e s/ear ar - 13 13% highe her Grain n wt wt - 22% 22% hi highe her
WATER F R FOR R PR PROFI FIT Water Use Efficiency, Critical crop Stages and Timings for Optimal Water Use, Pastures, Grass Seed, Clover Seed, Carrot Seed, Onions and Brocolli Tom Graesser
Irrigated P Pastur ures • Dairy Tas aim 1000 kg Dry matter per 100mm per ha (1ML) • $2-300 Drymatter per ML water? • Healthy perennial pastures(rye/white clover) • Pasture water use approx.= Full Pan evaporation • Rooting depth generally less than 60 cm • Need efficient system cost wise to pay for fully irrigated(5-6 ML/Ha) • Most efficient use is to start off a newly sown pasture or strategic water.
Lucern rne • Deep rooted, 1m or more • More efficient moisture use than ryegrass/white clover • Approx $600 gross value Lucerne per ML water (well managed, 2t/ML) • 4-5 ML/ HA per season • Critical to have well watered to about 3-4 days before cutting and fertilized and irrigated immediately after hay/silage removed
Ryegr egrass S Seed ed Prod oduction • Oregon and NZ work- Extra 4-8 kg clean seed per mm ($1000/ ML) • Most critical growth stage 2 weeks leading up to flowering • Second most responsive period 1-3 weeks after start flowering (ie up to within week of windrowing) • Anecdotally, in dry year like last year, big gains from maintaining adequate moisture after closing through to flowering.
White Clover r Seed • Approx $1200/ML • Critical stages are establishment early in Autumn and spring bulking up Mid Oct to Mid Nov • During Bulking up, need full Pan Evaporation replacement, aiming for about 3t drymatter by start flowering • During flowering and seed fill; controlled moisture stress-growthy paddocks about 33% full evaporation, others about 50%. More is not better!
Onions ns • 3-4 ML/ha, $2000/ML • Even establishment critical • Adequate moisture and growth 3-8 leaf stages for good symmetrical bulb shape • Water use drops to about 80 % of Pan Evaporation from mid bulbing onward • Night time irrigations best to Minimize Botrytis
Hybri rid Carrot S Seed • 5 ML/ha, $2000/ML • Establishment critical • Full Irrigation/rain up to flowering • Flowering to Harvest; Drip better Germination, yield and lower disease than overhead irrigation BUT overhead OK if overnight only and 20+ mm applications. • Anecdotally restrict moisture to about 25mm per week (60% full evaporation) during flowering/seed fill.
Broc occol oli • 3-4 ML/Ha, • Even establishment of crop critical to keep harvest costs down and maximize yields; Green Harvest • Shallow rooted- mature crop only about 40cm depth, first week 4cm. • Final week suggest under-watering Slightly to minimize risk of wet harvest (70% evaporation).
Sprout development Vegetative growth Tuber initiation Tuber bulking Maturation
Questions?
Establishment Post herbicide Run up Hook Flowering Stripey Capsule
Questions?
Soil moisture deficit reduces growth and can impact on nodulation Moisture stress during flowering and pod fill can severely limit yield and quality Excess water can limit yield (yellowing)
Questions?
Beans should be planted into moist soil and irrigated soon after Beans are sensitive to water stress during flowering, pod set and pod enlargement. Avoiding moisture stress during crop growth will aid in creating a moist, crisp bean. Lower production may be experienced if inadequate water is provided during pod enlargement leading up to harvest.
Thank you
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