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5th World congress of conservation agriculture Incorporating 3rd farming systems design conference

Irrigation performance and seasonal changes under permanent raised beds on Vertisol in Queensland,

Australia

Ghani Akbar (NCEA, USQ Toowoomba, Qld) Professor Steven Raine (FOES, USQ Toowoomba, Qld) Dr Allen Jack McHugh (NCEA, USQ Toowoomba, Qld) Mr Greg Hamilton (Maximum Soil & Water Productivity Pty Ltd. Perth WA)

26 to 29th September, 2011

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Water Scarcity Issues

Population growth

Inefficient irrigation systems

Land Degradation

Issues

Intensive cultivation

Seasonal changes

Water Use Efficiency

Issues

Irrigation manageme

nt

Agronomic manageme

nt

Major Agricultural Challenges

Introduction

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1. Water Scarcity Issues

a) Population

- Population growth increase pressure on available water resources

- (2000-5000 Litres/day) is required to support a single person diet

b) Inefficient irrigation systems

- Only 20% global cultivated land is irrigated

- Irrigated lands produce 40% world food

- Utilise 70% of global water withdrawal

- Inefficient & poor irrigation management

(There is need for the efficient use of available water

to meet the growing food, fibre & domestic needs)

Figure : Percentage of cultivated area equipped for irrigation Source: FAO-AQUASTAT

Figure : Global water withdrawal by sectorSource: WWI from P.H. Gleick (1993),Water in crisis, Oxford University Press

Introduction

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2. Land Degradation Issues

a) Intensive cultivation

- Damages soil physical, chemical and

biological health

- Causes erosion, crusting, sealing, loss of OM

& nutrients thus productivity decline

b) Seasonal changes

- Wetting, flowing water, rainfall hammering slaking, shrinking, swelling & subsidence

- Affect soil hydro-physical properties which also affect irrigation & crop performance

- Maintenance cost also increase

( There is a need for adoption of soil friendly agronomic practices for improving soil health& stability on sustainable basis)

Fresh bedSubsided bed

Seasonal changes

Intensive cultivation

Introduction

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3. Water Use Efficiency (WUE) Issues

• WUE is a generic term used for indicating water use in crop production. (GPWUI, IWUI, CPWUI,...) (Burett Purcell & associate, 1999)

a) Irrigation management

• Type of irrigation system

• System efficiency & uniformity(Ea, Er, DU etc)

b) Agronomic management

• Land management & tillage

• Cropping management

• WUE improvement is the key for producing more food with less water

(Under the prevailing water scarcity and declining land productivity situationsWUE improvement on sustainable basis is essential for future food security)

Water Use Efficiency

Irrigation Issues

Agronomic

Issues

Introduction

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Research opportunities

• Past NCEA studies identified furrow irrigation (Ea) 30-60% and reasons were attributed to excessive deep drainage losses, poor irrigation management and field design issues. They identified 85-95% achievable (Ea) by better irrigation management & field design.

(Raine & Bakker, 1996; Smith et al. 2005)

• Similarly improved soil amelioration (i.e. better structure, porosity, hydraulic

conductivity) were reported under the rain-fed Vertosol soil condition by adopting zero till control traffic farming.

(Tullberg, 1988, McGarry, 2001, McHugh et al. 2003)

• However, evaluation of current PRB farming system affected by variable bed furrow configurations, soil management, subbing and their impact on irrigation management strategies were rarely considered.

Literature Review

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Objectives:

Evaluate the irrigation performance of existing PRB farming systems under Australian vertisol soil conditions

To identify potential for lateral wetting front infiltration from furrow to centre of bed

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Methodology

Field trials: Site 1: Marinya farm, Cambooya (Soybean) Site 2: Bandawing farm, Dalby (Cotton)

Data collection Tillage and field information Irrigation inflows Flow advance along furrows Runoff at tail end Furrow geometry & slope

(Use of IRRIMATETM tools)

Use of IPARM & SIRMOD for performance evaluation

Soil moisture movement across the bed (Using

assembly of Sentek (Enviroscans) for lateral wetting front infiltration (Cambooya)

Use of SIRMOD for irrigation performance optimization

(Er≥ 85%, Water arrival to furrow tail, maximum water saving)

Advance Sensors

Flume with flow meter

Siphon with flow meter

9Methodology

Layout of Sentek (enviroscans) sensors placed across the bed for logging wetting front penetration into bed centre at Marinya farm Cambooya

Results

Site 1: Irrigation 1: Narrow furrows, loose soil

Site 2:

Irrigation 2: Cracking due dry soil conditions

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0 50 100 150 200 250 300 350 400 450 5000

200

400

600

800

1000

1200

Irrigation 1Irrigation 2

Distance along furrow (m)

Ad

van

ce t

ime

(min

)

Figure: Measured advance curves of two irrigations to soya bean at Marinya farm Cambooya (bars shows +/- standard deviation)

0 50 100 150 200 250 300 350 400 450 5000

100

200

300

400

500

600

700Irrigation 1Irrigation 2

Distance along furrow (m)

Flo

w a

dva

nce

tim

e (m

in)

Figure : Measured advance rate during two irrigations of cotton crop at Bandawing farm, Dalby (bars shows +/- standard deviations)

Results 11

Figure : Cotton crop at Bandawing farm near Dalby with (a) measured irrigation 1; (b) measured irrigation 2 with flow crossing the bed through cracks due to dry soil conditions

Results 12

Site Strategies Q(L.s-1)

Tco (min)

Ea (%)

Er (%) DU (%) Inflow

(m3/ha)

Water saving* (%)

Cambooya

Farmer managed

1.94(0.1)

1100(61)

73(6)

100(0)

90(3)

1393(113)

1. Tco optimised

1.94(0.1)

921(84)

80(8)

92(2)

74(3)

1167(137) 16.2

2. Tco & Q optimised

3.25(0.7)

425(88)

98(1)

85(0)

88(3)

879(11) 37

Dalby

Farmer managed

2.54(0.1)

635(64)

79(8)

97(2)

87(1)

1062(84)

1. Tco optimised

2.54(0.1)

473(121)

97(1)

88(3)

77(2)

790(186) 25.6

2. Tco & Q optimised

3.125(0.2)

370(40)

97(3)

85(0)

82(4)

762(125) 28.3

Table : Impact of irrigation management strategies on current irrigation performance of two sites under black cracking Vertisol soils in southern Queensland, Australia, (values in brackets are +/- standard deviation).

*Water saved as compared to farmer practice

Results 13

Figure : Relationship of optimum Tco vs. Q, average values of two irrigations, with predicted irrigation performance (Ea, Er and DU) at two sites.

Results 14

0 100 200 300 400 500 6000.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

4.501 L/s2 L/s3 L/s4 L/s5 L/s

Furrow length (m)

Tco

/Ta

Figure: Effect of furrow length and inflow rate on the ratio (between time to cut-off and time of advance to tail end) for achieving Er≥ 85% and flow arrival at tail end (Cambooya: irrigation 1).

Results 15

Figure : Temporal and spatial variations in lateral water infiltration across 2 m wide bed at (a) 33cm, (b) 67cm and (c) 100cm from furrow centre during summer 2010 (soya bean) at Cambooya, Qld, Australia.

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Conclusions

The current irrigation management is not optimal , often longer Tco and lower Q than optimal are practiced under farmer managed conditions.

Majority of current soil management/raised bed renovation practices are not optimal leading to low irrigation performance and poor water use productivity.

The current bed furrow configurations are largely not optimal causing poor irrigation performance and crop establishment leading to low WUP.

Subbing is not a significant problem under the current irrigation management of Australian farms with lengthy furrows and prolonged irrigation cut-off times but can affect crop performance especially at tail end if infiltration opportunity time is not sufficient (i.e. <5 hours in the case evaluated).

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1st Irrigation at Cambooya

Bulk Density and soil moisture data

2nd irrigation Soybean crop

Data recording

The EndThanks all of you