Irrigated agriculture R&D underpinning practice/change: - PowerPoint PPT Presentation

Irrigated agriculture R&D underpinning practice/change: hydrology research Lucy Finger February 2008 Department of Sustainability and Environment Department of Primary Industries

Hydrology group research • Salinity impacts of water trade • Water use efficiency benchmarking • Irrigation Futures • Scenario development – agriculture adaptation to climate change • Improving irrigation practices (dairy industry) – Border-check irrigation – Irrigation technology comparison – Sprinkler irrigation – Subsurface drip irrigation

What is subsurface drip irrigation? • Water supplied to rootzone via tube • Low operating pressure, low flow rates (<5 L/hour) • Continuous or pulsed application • Fertigation Wetting pattern in SSD irrigation • Costs $6000 - $8000/ha Pump Filter Irrigation Controller Air and Control valve Air and vacuum (solenoid) vacuum release release Flushing valve valve valve Flushing Water Mainline Connector Drip tape (with Connector supply manifold Submain emitters)

S u b s u r f a c e d r i p i r r i g a t i o n o f g r a z e d d a i r y p a s t u r e s O b j e c t i v e : T o e x p l o r e , e v a l u a t e a n d d e m o n s t r a t e t h e f e a s i b i l i t y a n d w i d e r b e n e f i t s o f u s i n g s u b s u r f a c e d r i p i r r i g a t i o n f o r p a s t u r e p r o d u c t i o n , a n d t o m a k e c l e a r r e c o m m e n d a t i o n s a b o u t i t s a p p l i c a b i l i t y t o t h e d a i r y i n d u s t r y P r o j e c t 2 : D e p a r t m e n t o f P r i m a r y I n d u s t r i e s P r o j e c t 1 : U n i v e r s i t y o f M e l b o u r n e F o c u s : F e a s i b i l i t y i n d a i r y c o m m e r c i a l o p e r a t i o n s F o c u s : T a r g e t e d e x p l o r a t i o n o f l i m i t i n g c r i t e r i a a n d c a t c h m e n t i m p l i c a t i o n s F a r m C o n t r o l l e d L a b o r a t o r y F i e l d S t u d i e s S c e n a r i o E x p e r i m e n t s ( D o o k i e ) B u i l d i n g E x p e r i m e n t s A n a l y s i s a n d M o d e l l i n g ( f a r m & c a t c h m e n t s c a l e s ) B e s t b e t d e s i g n s & v a r i a t i o n s  G e o t e c h n i c a l I r r i g a t i o n s c h e d u l i n g  F o r d i f f e r e n t s o i l s : P r o d u c t i o n a n d w a t e r u s e  G r a z i n g m a n a g e m e n t  C o m p a c t i o n b e h a v i o u r I m p a c t o f w a t e r q u a l i t y U s i n g w o r k s h o p s a n d  W a t e r f l o w a n d s o l u t e  W a t e r u s e & p a s t u r e  V e g e t a t i o n i m p a c t a n d g r a z i n g i n t e n s i t i e s . D a i r y M o d .  m o d e l l i n g p r o d u c t i o n P u g g i n g t h r e s h o l d s  T h r e s h o l d i d e n t i f i c a t i o n  W a t e r a n d s o l u t e m o v e m e n t  M o d e l l i n g s c e n a r i o s t o P l o t t r i a l s , w i t h t h r e e S u c c e s s F a c t o r s  O t h e r e n v i r o n m e n t a l a s p e c t s  i d e n t i f y t h e p r a c t i c a l i t y t y p e s o f t a p e , t w o E c o n o m i c a n a l y s i s  s p a c i n g s a n d t w o o f S S D i r r i g a t i o n , a n d i n s t a l l a t i o n d e p t h s w h e r e t h e g r e a t e s t C h e m i c a l E n g i n e e r i n g e c o n o m i c a a n d W a t e r q u a l i t y t o l e r a n c e s : p r o d u c t i o n b e n e f i t s w i l l E m i t t e r t y p e s & c l o g g i n g  o c c u r ( f a r m a n d C a t c h m e n t s u p p o r t F i l t r a t i o n r e q u i r e m e n t s  F a r m s c a l e i n f o r m a t i o n p a d d o c k s c a l e ) B i o f o u l i n g i n f o r m a t i o n  L i f e s p a n & m a i n t e n a n c e  F e a s i b i l i t y a n d b e n e f i t s  C h a n g e s t o w a t e r a n d  A p p r o p r i a t e d e s i g n ,  s o l u t e b a l a n c e s i r r i g a t i o n s c h e d u l i n g a n d C a t c h m e n t i m p l i c a t i o n s  m a n a g e m e n t , g r a z i n g ( w a t e r q u a l i t y a n d w a t e r c r i t e r i a , f o r v a r i e t y o f s o i l m a n a g e m e n t ) t y p e s

Experiment overview • Conducted between July 2006 and June 2009 • Two sites (one “light” soil, one “medium” soil) • Controlled experiments on commercial dairy farms Treatments • Three tape spacings and two irrigation frequencies • Fertigation regime constant (apply 25 kg N/ha after each grazing) Measurements • Pasture production and composition • Water use, water balances, solute movement and water quality • Soil structure indicators, performance & longevity of SSD system

Tape installation, September 2006 ~ 19 km tape at Byrneside ~ 11 km tape at Bunbartha

Head works at Bunbartha, October 2006

Experiences with pasture establishment, Byrneside (medium soil) 0.6 0.6 m m 1.0 1.0 m Wetting patterns after 30 mm of water applied, October 2006, Byrneside 1.4 1.4 m m

1.4 m spacing, 19 Oct 2006, 9 days after irrigation started (84 mm)

1.4 m spacing, 14 Dec 2006, 65 days after watering commenced.

1.4 m spacing, 25 March 2007

Experiences with pasture establishment, Bunbartha (light soil) Different wetting patterns, after 185 mm water 1.0 m 1.4 m 0.6 m

Wetting up dilemma: spreading water vs excessive ponding

1.4 m spacing, 16 nov 2006

1.4 m spacing, 15 Dec 2006

1.4 m spacing, 05 March 2007

First grazing, December 2006/January 2007

Experiences with pasture establishment, Byrneside (medium soil) Pasture growth for the different tape spacings, May 2007 1.0 1.0 m 0.6 0.6 m 1.4 1.4 m

Experiences with pasture establishment, Bunbartha (light soil) Pasture growth for the different tape spacings, April 2007 0.6 0.6 m 1.0 1.0 m 1.4 1.4 m

Effects of grazing

Results 2006/07 season: Water balance 01/10/06 to 15/05/07 Byrneside Bunbartha P: 147 mm P: 125 mm Et: 1052 mm Et: 1074 mm RO: ~0 mm RO: ~0 mm Δ S: 74 mm Δ S: 23 mm I: 962 mm I: 1188 mm D + errors: 238 mm D + errors: 39 mm

Results 2006/07 season: Bunbartha rootzone soil moisture 250 200 150 moisture (mm) Trouble with pump, 20 Dec to 19 Jan (affected 1.4 m bays) 100 Bunbartha 0.6 m Bunbartha 1.0 m 50 Bunbartha 1.4 m ESfsl wilting point ESfsl saturation 0 01/10/2006 20/11/2006 09/01/2007 28/02/2007 19/04/2007 08/06/2007

Results 2007/08 season: Rootzone soil moisture (neutron probe) 300 250 soil moisture in rootzone (mm) 200 150 Irrigations commenced 17/09/07 100 Byr 0.6 m Bba 0.6 m Byr 1.0 m Bba 1.0 m Byr 1.4 m Bba 1.4 m 50 Ll wilting point Ll saturation ESfsl wilting point ESfsl saturation 0 01/07/2007 20/08/2007 09/10/2007 28/11/2007 17/01/2008

Results: Rootzone soil moisture (Bunbartha) 1.4 m 0.6 m 1.0 m (4D) 1.0 m

Results 2006/07 season: Pasture production 10 9 Byr - total grown Byr - total consumed Bba - total grown 8 Bba - total consumed 7 6 DM (t/ha) 5 4 3 2 1 0 15/08/2006 4/10/2006 23/11/2006 12/01/2007 3/03/2007 22/04/2007 11/06/2007

Results: Pasture composition Change in pasture composition 90 80 70 % in pasture sward (by weight) 60 Byr ryegrass Byr clover 50 Byr weeds Bba ryegrass 40 Bba clover Bba weeds 30 20 10 0 Summer 2006/07 Autumn 2007 Spring 2007

Results 2006/07: Efficiency measures Measure Tape Spacing Irrigation Efficiency (%) 0.6 m 1.0 m 1.4 m Byrneside 98 97 96 Bunbartha 90 91 92 0.6 m 1.0 m 1.4 m Agronomic WUE TW (kg.ha -1 .mm -1 ) Byrneside 7.1 6.8 7.4 Bunbartha 6.8 5.6 5.2 0.6 m 1.0 m 1.4 m Agronomic WUE I (kg.ha -1 .mm -1 ) Byrneside 6.2 6.0 6.5 Bunbartha 7.6 6.3 5.9

Findings – 2006/07 season • Subsurface drip irrigation maintained pasture production despite drought conditions • Subsurface drip irrigated pasture can be grazed in summer without pugging or damage to irrigation system • Pasture establishment and germination: – If possible, germinate and establish pasture using rainfall – On medium soil, can use SSD irrigation to establish pasture using relatively little water – On light soils, do not use SSD irrigation for establishment (significant water loss) • Differences in pasture production but compromised