Field Days/Farm Trials

At the Padman Stops Trial Site at Strathmerton.

Padman Stops' John Padman spoke about how his trials have shown the faster the water is applied to a bay, the less water is used, with better control of application on all bays. The best way to achieve the perfect irrigation is to set up the Fast Watering Technique to achieve a 40 to 50mm application under any soil condition and then slow the watering down as required, depending on soil condition and crop's grown.

Franks Final Grade
Dugong Series Grader Scrapers
An innovation not yet available anywhere else in the world. To be made in many sizes only one available as yet, this innovation has seen half of the hydraulic rams removed, changing forever the way in which a Grader Scraper can move, producing a unique Grade or finish no other machine could reproduce.
Many other hydraulic ideas have been addressed to give one simple machine capable of doing the same thing from 30 hp 800 hp.
Three hydraulic rams total, one for each function of the Dugong Series Grader Scraper.
• Raise & lower
• Open & Close of Apron or bin door to carry or release material.
• Tip up & down bin or to gather or empty material.
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A Grader Scraper platform strong enough to attach farming, horticulture & construction tools to or used as a site ute back come trailer. Check with your engineer and oh&s adviser for more informed question and answer, the load limit is available on web pages & brochures.
1400 / 500 kgs .....2200 / to be advised........3000 / to be advised.........3500 / to be advised......4000 / to be advised.......5000 / to be advised
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Simple wearing bolt up changeable parts, laser cut using international steel standards for local business dealings with a choice of cutting house & repairer. Quality as is new when replacing well know wearing parts bring back to life a feeling & as new actuating Grader Scraper.

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Changeable parts to suit application would be wheels ( sizes, diameter, width, number) / blade ( different shapes, lengths, / thickness will help with wear & change how the material loads & unloads ) / Apron can be arranged to restrict the flow of material to prevent the situation of loading for sake of loading even if the material can not fit in the machine and flows over the side or known as continuous loading. This could put unnecessary stress and significantly reduce the life of all parts & the machine itself.
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Although size is an issue when revering to the 1400 Series it does have options like combination or road train format. It's use as a cheaper farm utility or module giving farms the flexibility to purchase dispose cycle distribute machinery about the farm with a greater range or scope. Furthermore with option to be able to do the things bigger machines of this type can do other than the larger faster volume of dirt it still can perform all other duties like plant root work for changes of plant in areas or diseased roots ( blades serrated or fingered would work better here). This model is recommended for irrigation farmers 1-1000 acres for general farm use. Water flow though changes of grade and depth in ditches would be a recommended where applicable to crop or watering technique. Small changes of grade could take place in a bay by bay basis to suit crop, watering, weed, salt and could be done in a winter setting because the machine is smaller it would take just the dry dirt from the top giving a greater range of times and places for work to be done from a farm irrigators point of view controlling ground moister almost at will. A strong frame and place to mount a laser receiver to also though and recommended to place a ute trailer type platform to perform more duties with the scraper platform as well as the rear tow hitch which are all standard equipment on this size. Finally Franks Final Grade also believes moving other equipment to the Grader Scraper platform will reduce the risk of injury by implements being used mostly because of a guard or moving components are further from the operator and as a trailing implement the tractor would give warning of approach for others and a safer on and off the tractor for the operator, prevention of roll over caused by the implement is seen by Franks Final Grade as a balance of the Grader Scraper taking the load rather than linkage.
For more information contact:
Graham Walsh
Franks Final Grade
50 Polaris Ave
Kingston 4114
Queensland
dugong1400series@franksfinalgrade.com.au

www.franksfinalgrade.com.au

GROW MORE WITH LESS SUB -SURFACE DRIP
IRRIGATION FIELD DAY
Netafim, together with NVIRP, held the "grow more with less" Field Day at the Dixon farm Cnr of Davies and McKenzie Road, Merrigum.
The Dixon’s successfully established a 60 acre SDI block for lucerne in 2007 to supply additional feed for their dairy herd.
The day featured farm walks covering all aspects of SDI and formal presentations from leading
personnel in the fields of:
• Sub-Surface Drip Irrigation
• Lucerne Agronomy
• Farm Modernisation
• Whole Farm Plans
• Rural Finance
NVIRP Modernisation Coordinators and Irrigation Farm Designers were available to discuss farm plans.
Farmers were given the opportunity to discuss their future farm requirements.
A bbq lunch and refreshments was enjoyed by approx 100 people.
For more details please contact Darren Kell on 0419 362 845 or email dkell@netafim.com.au
[image|55]

Field day 3. The future of Irrigation field day, by far the biggest the Murray Irrigators Support Group partnered with Padman Stops and NVIRP with six guest speakers from a whole farm plan perspective, to showcase a Royals Royce farm upgrade in Katunga where even the Premier John Brumby attended.
Farmers came to see the outstanding results from the delivery chanell to grass roots.The new techniques for the establishment of lucerne with 50% water savings.White rock channels, reconfigured supply channels, and automated meters.

Field day 2.
At Mark and Monique Bryant's.
By “fast watering” and using Padman Stops, Mark said he had cut his watering time in half - down from 24 hours for eight hectares, to 12 hours. On the advice from my agronomist to do a second watering four days after the first, no matter what,” Mark explained. “I’ve halved my water consumption, and last year still managed to produce more than 12 tonnes of feed to one hectare of land and 4.2 megalitres of water,” he explained.

Field day 1. At the Padman Stops Trial Site at Strathmerton.

Padman Stops' John Padman spoke about how his trials have shown the faster the water is applied to a bay, the less water is used, with better control of application on all bays. The best way to achieve the perfect irrigation is to set up the Fast Watering Technique to achieve a 40 to 50mm application under any soil condition and then slow the watering down as required, depending on soil condition and crop's grown.

Paper prepared by
Harry Kooloos
“Amarran”, Mayrung NSW
Sam North
Hydrologist, NSW DPI
Deniliquin NSW
email: jkooloos@bigpond.com.au
IREC
C/- CSIRO Land and Water, Griffith
Private mail bag 3 Griffith NSW 2680
Tel: 02 69601550 Fax: 02 69601562 Email: irec@irec.org.au
GRDC
FOR IRRIGATION CROPPERS
2007
Page No 1
2007 GRAINS RESEARCH UPDATE for irrigation croppers
The new “V-Bay” flexible layout
Harry Kooloos / Sam North
Introduction
Rice is seen by most irrigators with General Security access licences in the irrigation districts of southern NSW as their most profitable and reliable crop and 50-60% of all water delivered to these districts is used to grow rice. Contour systems constitute roughly 50% of the area laid out to irrigation in southern NSW and, to minimise deep percolation and ensure good water depth control, these systems are located on impermeable, often sodic, heavy clay soils in (very) flat terrain. Rice businesses are generally growing and viable, but returns per megalitre (ML) are relatively low for the most limiting resource: i.e. water (Cummins & Thompson 2002). Despite the low return per ML, contour systems are profitable because of their very low labour and capital requirements (Rendell McGuckian 1998). However, the low return per ML places a heavy reliance on businesses to maintain scale (ML/family) and the high per hectare (ha) water use makes production sensitive to water price and availability (Denimein LWMP Working Group 1995).
The general decline in the terms of trade for agricultural commodities and the increasing cost and decreasing availability and reliability of irrigation water is affecting irrigated farm profitability in these districts and indications are that these pressures will increase rather than decrease. Rice farmers have maintained their profitability in the past by increasing the scale of their enterprises and buying in more water and this used to be easy to achieve. However, pressures facing irrigators make it increasingly difficult for them to maintain their profitability in this way. Switching out of contour irrigation into row-cropping or more intensive industries is difficult and expensive and switching to border check systems offers little prospect for maintaining farm profitability (Rendell McGuckian 1998). There is also little incentive to switch from annual crop systems to more capital intensive industries (e.g. horticulture and dairying) because of the uncertainty and risk associated with the low reliability of supply for irrigators with General Security licences in southern NSW (Frost et al. 2003). There is thus a need to find ways to increase the profitability of rice based farming systems which retain the advantages of basin systems but which return more per ML, are better adapted to a lower and more variable irrigation supply, and do not require a large capital investment.
One way to achieve this is for irrigators to allocate water to winter crops in years when water is limiting, rather than growing rice. This strategy derives from economic theory which states that profits are maximised when net returns to the most limiting resource are maximised. Beecher et al. (1995) showed that gross margins to land, labour and capital are higher for rice than for viable alternative crops, so the most profitable strategy when water is plentiful is to use water to grow rice. When water is limiting, the most profitable strategy is to spread available irrigation water equally over a larger area and maximise the average net return per ML (Yaron & Bresler 1983). In Mediterranean climates, this is achieved most effectively by using available irrigation water to supplement winter rainfall and deficit irrigate winter crops (Stewart & Musick 1982; North 2005a).
Rice growers in southern NSW are reluctant to adopt this strategy because of the risks associated with waterlogging in winter and after spring irrigation (North 2004b; North 2005b). Thus, for this strategy to be successful, watering and drainage times in basin layouts need to be improved so higher yields of winter crops can be achieved with lower risk. Furthermore, this needs to be done in a way that improves the net returns to land, labour and capital from winter crops. If this can be done, then the shift to a more flexible cropping system will provide a viable alternative to predominantly rice based systems.
Evolution of “drive-over banks”
A system for achieving these outcomes has been developed in the Berriquin Irrigation district over the past five years. Initially, Nick and Steve Morona, “East Rostella”, Deniliquin, wanted to develop a contour system that had greater versatility than current contour designs, was quicker to water and drain, and which had better access into and within paddocks. They developed check banks along the contour that were wide and had low slope so they could be driven over. This allowed paddocks to be trafficked up and down the slope, rather than perpendicular to it, and improved machinery efficiency, weed control on banks and paddock drainage in winter.
2007 GRAINS RESEARCH UPDATE for irrigation croppers Page No 2
The new “V-Bay” flexible layout Harry Kooloos / Sam North
Morona’s system, which has been described at a previous GRDC Update (Morona 2005), had a number of distinct advantages over conventional contour systems. These included:
• 6% more crop area because banks can be cropped;
• lower chemical use as banks are cropped and are no longer sources of weed seed;
• increased labour and machinery efficiency because there is less turning and headlands;
• they eliminated the need for cross-overs which concentrate traffic and cause compaction and restrict paddock drainage if not properly installed or maintained;
• better drainage was achieved by sowing with the slope;
• drainage was better for 80-100 m wide contour basins than if paddock had been converted to border check bays down the slope with 400 m long bays;
• long runs made it possible to adopt control traffic and precision farming systems, there-by reducing costs and increasing machine efficiency.
There were however a number of disadvantages to Morona’s system:
• it was hard to maintain a constant sowing depth with the air seeder over drains/banks;
• a road grader was needed to pull down/up banks if dirt is only pulled one way;
• it was necessary to drive through wet drains if sowing occurred shortly after a pre-irrigation.
The Kooloos’ “V-Bay”
Harry Kooloos, “Amarran” Mayrung, saw Morona’s system and felt he could improve upon it. After some consideration and discussion with his earthmoving contractor, the Kooloos “V-bay” was born. In this system, paddocks that were originally landformed on a single plane (slope 1:2000) were re-graded within each bay to a double slope of 1:1500 which drained to the centre (see Figure 1). A drain, 5 cm deep and one scraper blade in width, is cut down the centre of this V along the middle of each bay and, to further improve drainage, a spinner cut is made down the centre of the centre drain. Paddocks have a side-ditch along both ends of the bays. Channel stops are placed in the head supply/drainage side-ditch and 300 mm pipes in the side-ditch at the opposite end of the bay in order to speed drainage. Bays do not have slope along their long axis and check banks are constructed so that they can be driven over, allowing the paddock to be trafficked with the slope.
The “V-bay” has all the advantages of Morona’s system and overcomes its principal disadvantages:
• the check banks are on the high side of each bay so they don’t need to be as high, making them easier to drive over, less likely to crack through and leak, and amenable to being pulled down/up with non-specialised machinery (see Figure 2);
• trafficability down the paddock is improved by placing drains down the centre of the bay and at some distance from the check banks;
• the double slope in each bay means that only half the volume of water is needed to fill the bay and get complete coverage, resulting in quicker watering and drainage times and reducing the likelihood of water backing up in drains. (This creates the option to increase the bay size and reduce the number of structures).
The “V-bay” system may still have some disadvantages, principally in the additional cost associated with moving larger volumes of earth and potentially if top-soiling is not done and heavy cuts expose unfavourable sub-soils. There may also be a minor problem with trafficking through the centre drain in wet years, but this should be easy to overcome. However, in theory, this system has the potential to markedly improve the
2007 GRAINS RESEARCH UPDATE for irrigation croppers Page No 3
The new “V-Bay” flexible layout Harry Kooloos / Sam North
irrigation efficiency of contour systems, reduce the risk of waterlogging and so improve winter crop yields, and improve machine and operational efficiency. All these aspects will be assessed this coming irrigation season and compared to the performance of conventional contour designs in a project funded by the Murray LWMP’s and conducted by NSW DPI staff at Deniliquin.
Figure 1. Vertical (top) and side-view (bottom) plan representation of Kooloos’ “V-bay” basin system.
Figure 2. The Kooloos “V-bay” drive over bank seen in profile

Bennett Clayton Engine Technology
Bennett Clayton Pty. Ltd.
Is an engine development company specialising in the development and implementation of alternative fuel conversions for existing diesel engines.

The Bennett Clayton technology, invented and patented by John Bennett in the 1990’s, enables the conversion of diesel engines to a range of alternative and/or renewable fuels including LPG, LNG and bio-alcohols (including methanol and ethanol). These engines are designed to operate in traditional heavy-duty applications delivering significant improvements in fuel efficiency, power and reduced emissions.
Bennett Clayton’s current development focus is principally the conversion of stationary diesel engines to LPG, as this fuel is locally produced; widely available and supported by a well established and extensively distribution infrastructure.
Diesel to LPG conversions have been implemented in a range of stationary and mobile diesel engines including MAN metropolitan transport buses; Mercedes Benz trucks; London taxis; Nissan utility truck; Toyota Landcruiser truck and on stationary engines used for deep bore water pumping and electricity generation.
In every case, the converted engines have delivered significant benefits in terms of emissions, running costs and operational improvement
A John Deere 6068 diesel engine was remanufactured incorporating a Bennett Clayton LPG conversion.
The engine has been developed on order for an agricultural application powering a deep bore water pump.
Engine No.1 of the type was developed as a proof-of-concept and development bed. It has been in field operation since April 2009 delivering the following performance benchmarks:


•Pumping costs reduced from AU$51/Ml to AU$38/Ml

•Greenhouse gas emissions (GHG) reduction of 11%

•Regulated emissions reduced by up to 92%Particulates reduced by 99.9%

Sophisticated combustion design, and thoughtful engineering are required to produce a motor that is simple and maintenance friendly, yet super clean and efficient.

This engine will provide years of service, using LPG, and is ready for future alcohol fuels.

Bennett Clayton engines are essentially multi-fuel ready and can be optimised to other fuels, such as bio-alcohols, with little adjustment and modification.

Bennett Clayton delivers customer product requirements right first time by implementing a rigorous and comprehensive product quality assurance; reliance on high integrity materials; meticulous process control; and by embedding quality engineering in processes, procedures and team ethic.

Farm Fuel Rebates

Farmers enjoy a Commonwealth Government rebate of about 38c per litre for diesel fuel used on the farm.

A major on-farm diesel fuel use is driving irrigation pumps. ABARE reports an estimated 142,000 licensed bores in Australia. In addition, there are at least that many surface pumps.

The vast majority of these pumps are diesel-powered as electricity is only viable if the pump is near power infrastructure, and wind is mostly suitable for low-flow applications.

Multi fuel engines, powered by LPG and bio-alcohols (methanol and ethanol) are available now to replace the current diesel engines.

These alternative fuel engines have demonstrated reliability, having operated in the field for thousands of hours. They exhibit extremely low emissions, and reduced CO2 production. They are more economical than diesels, both in fuel cost, and in maintenance. They are built in Australia.

However, their take up in the market is hampered by the distortion created by the diesel fuel rebate. On an even playing field, alternative fuel engines are very competitive and would be taken up more rapidly.

We are asking that the diesel fuel rebate scheme be changed to a fuel rebate scheme, with the rebate applied to a fuel in proportion to its energy content.

This would mean that diesel would attract a rebate of in round figures 38cents,
LPG 24 cents, Methanol 18 cents and Ethanol 23 cents.

These rebates would provide parity to diesel, and remove a major objection and barrier to the adoption of cleaner, friendlier and ultimately carbon negative fuels.

This small change will have a significant impact on emissions, and CO2 production as well as providing industry development and employment in regional areas.


Marcus Clayton
0429352570

148 The Boulevard
Ivanhoe East Vic 3079
0429352570
info@bennettclayton.com.au
www.bennettclayton.com.au

Fast Watering by John Padman

Definition of fast watering: Surface Irrigation applied faster than 10 ML per day

In 2006, Padman Stops began their “Fast Watering” project, with the aim of creating a high efficiency irrigation system.

The theory behind the system was that irrigating faster than the water can soak below the root zone would result in higher efficiency.

John Padman, with this in mind, built a pump with a flow meter that could be used in a trial to measure the effect of “Fast Watering”.

Trials conducted have found that the faster the water, the less water is used.

In one trial the application rate of the pump was found to be down to 0.3 mega-litres (30mm application) of water per hectare compared to 0.77 mega-litres (77mm application) per hectare for conventional irrigation.

Water Saving Advantages:
Additional water can be used to grow more feed.
Reduced water logging, and soil degradation.
Increased plant growth, and reduce weed growth.
Minimize leaching of nutrients.
Low energy, green irrigation is more carbon efficient.

Keys that control infiltration rate.
Watering speed---Soil Condition--- Plant Density Soil Type---Length of Bay--Slope of Bay.

What is the best application rate?
Suggested application rates vary from 30mm to 75mm. (0.3-0.75MLperHA.) In most cases 40mm to 50mm is sufficient.
Smaller applications are suggested for watering up of seed such as Lucerne or cereals.
Heavier applications are needed for deep rooted plants such as Lucerne.

The Key to high efficiency irrigation is to apply the correct application for each situation.

Infiltration rates will change with cultivation and crop density through the life of the layout
Installing larger stops today could cost as little as $40 extra
To upgrade later could cost you in excess of $500

Demonstration of Surface Irrigation Evaluation Technology in the
Goulburn Murray Irrigation District
Report 1: Evaluating the Performance of Bay Irrigation in the GMID
R.J. Smith1, M.H. Gillies1, M. Shanahan2, B. Campbell3 and B. Williamson4
1 National Centre for Engineering in Agriculture and CRC for Irrigation Futures, University of
Southern Queensland
2 RM Consulting Group, Bendigo
3 Price Merrett Consulting, Kerang
4 CRC for Irrigation Futures, Dubbo
Corresponding Author: smithrod@usq.edu.au
Note this report is currently pre-press and final draft.
ABSTRACT
The CRC for Irrigation Futures recently undertook a project piloting use of the IrriMATETM
performance evaluation process in bay irrigation at a number of sites across the GMID. This
evaluation technique, which was developed originally for furrow irrigation, is now well accepted
in the cotton industry.
The project successfully demonstrated that evaluation of performance can lead to substantial
realisable gains in efficiency for bay irrigation, including the ‘good’ irrigators. For the irrigations
evaluated, application efficiencies averaged 72% and realisable gains in efficiency of 19% are
possible with changed management. For most farmers this will mean application of higher flow
rates and shorter irrigation times. Practically this means on-farm automation.
The evaluation process provides the means to determine the preferred flow rate and irrigation
time for automated systems and also the means for identifying optimum capacities for farm
outlets. This latter data is of interest to scheme modernisation design, because flow rates
available to irrigators through their meter outlets are often less than required for maximum
performance on farm.
The project identified some deficiencies in the evaluation process caused by differences in the
management of bays compared to furrows, deficiencies which have now been overcome in the
development of new evaluation tools.
INTRODUCTION
Monitoring and evaluation of bay irrigation practices in Southern Australia is not new. It has
been used for a variety of purposes over many years, for example, to evaluate surface irrigation
simulation models (Maheshwari & McMahon 1993 a & b; Austin & Prendergast, 1997), for the
estimation of soil infiltration characteristics (Maheshwari and Jayawardane, 1992; Hume, 1993),
and for the comparison of alternative (surge flow) systems (Turral and Malano, 1996).
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In no case did the work lead to an assessment of the performance in efficiency terms of bay
irrigation or of the opportunities for improvement of performance. This contrasts directly with the
experience in the cotton and sugar industries where the focus of evaluations has always been
on performance improvement (for example, Raine et al., 1997; Dalton et al. 2001).
Recent use of the IrriMATETM evaluation system in Qld and northern NSW has engendered
confidence in those regions in surface irrigation evaluation techniques. The robust data sets
which are developed allow for the modelling of optimised irrigation events, and implementation
of the recommendations generally provides a unique match of modelling with reality. This
confidence has resulted in substantial change, despite the fact that adoption of the optimal
irrigation practice may require an increase in labour.
In northern NSW and Qld in the late 1990’s, irrigation application efficiencies varied widely from
17 to 100% with an average of 48% (Smith et al, 2005). Deep percolation (drainage) losses for
Queensland cotton fields averaged 42.5 mm per irrigation, representing an annual loss of up to
2.5 ML/ha /season. BDA Group (2007) estimated that the application of IrriMATETM in the cotton
industry has so far saved 400 GL over a 16 year period or 28.5 GL/annum and has contributed
to industry improvement in WUE of 10%, with anticipation of another 10% improvement in WUE
by 2014.
In the present study, field trials were conducted using the IrriMATETM system at a limited number
of sites with the objective to demonstrate the application of surface irrigation evaluation to bay
irrigated pasture and to indentify the potential gains in irrigation performance. Although the
sample of sites was small they provide an indication of the level of performance across the
GMID and the opportunity for substantial water savings through changed practice on-farm.
EVALUATION METHODOLOGY
Overview
The IrriMATETM evaluation system is both a set of measurement and simulation tools, and a
process that involves:
• Monitoring of an irrigation event(s);
• Inverse solution from the measured irrigation advance and other data to give infiltration
and surface resistance parameters prevailing during the measured irrigation;
• Simulation of the measured irrigation as a means of calibrating the simulation model and
calculating the performance parameters for the measured irrigation; and
• The conduct of ‘what if’ simulations to determine the flow rate and time to cut-off to give the
best or preferred irrigation performance.
Field Sites
A total of seven sites were selected at short notice by cold calling potential collaborators. A
geographic spread was intentional, in an attempt to cover a broad range of soil types and
configurations (Table 1). Some discrimination on pasture type was also made, with a preference
for permanent pasture. If anything, the sites were biased toward the more efficient irrigators,
because only those better irrigators had sufficient water remaining to be able to irrigate during
the study period.
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Table 1 Site details for irrigation evaluations
Site Location Soil Type Crop
Dimensions (m) Irrigation
Width Length Outlet Supply Schedule
S1 Strathmerton
Cobram loam, Moira
loam, Muckatah clay
loam
PP 63 324 Up-turn
pipe
Dethridge &
Bore -4.2 &
14.7 ML/day
14 day
S2 Kyabram Lemnos loam PP 55 473 Padman
stop
Pump 8.6,
7.1 ML/day 7 day
S3 Strathallan Rochester clay Lucerne 87.5 315 Padman Dethridge
11.2 ML/day 12 day
S4 Calivil Mologa loam PP 43 283 Slide Dethridge
4.6 ML/day
10 day
S5 Horefield
Cohuna fine sandy
loam, Leitchville sand,
Cullen loam
Lucerne 45.5 343 Straight
pipe
Dethridge
10.0 ML/day 14 day
S6 Normanville
Coombatook sandy
loam, Coombatook
sandy clay loam
Lucerne 61 435 Padman Dethridge
7.3 ML/day 12 day
S7 Stanhope Sandy loam Winter P 20 169 2.5ML/day
Field Procedure
Details of each site were collected including bay width and length, longitudinal slope (capturing
any changes in grade) and bay supply configuration. Typical slope was 1:750. Data collected
for each event included:
· the inflow hydrograph; and
· the irrigation advance (advance times for various points along the bay including the time for
the advance to reach the end of the bay).
The flow rate and irrigation advance were measured using the IrriMATETM suite of tools
developed by the National Centre for Irrigation in Agriculture (NCEA), as described by Dalton et
al. (2001). The inflow into the bay was measured using a large throated custom designed flume
(Figure 1) with capacity up to 15 ML /day. The instrumentation monitors depth through the flume
continuously throughout the irrigation event to record both the total inflow volume and the full
inflow hydrograph. Water advance was measured using electronic contact sensors positioned at
six points along the length of the bay. Each sensor consists of eight pairs of wire contacts
connected to separate timers spread transversely across the bay in an attempt to overcome
spatial variability of advance rates.
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Figure 1 Measurement of inflow into the bay (Photo courtesy of Phil Price)
In order to provide meaningful efficiency values the evaluation process also requires reliable
estimates of the soil moisture deficit prior to the irrigation event, and this becomes the target
depth of application. In this study the soil moisture deficit was estimated from ET (either pan
evaporation or Silo ETO) and estimated pan and crop factors as appropriate. In most cases the
deficits were higher than would usually be the case because of the current water shortage.
Analysis and Simulation
The time dependent soil infiltration characteristic is defined using the three parameter modified
Kostiakov equation, one of the most commonly used empirical functions for surface irrigation.
The depth of infiltration, Z (m3/m2) due to water present on the soil surface for time τ (min) is
given by:
t t o
Z = k a + f (1)
where a and k are empirical parameters and fo (m/min) is the final or steady intake rate of the
soil. The parameters of the infiltration function and the hydraulic resistance to flow (Manning n)
provided by the pasture are typically evaluated using an inverse solution of the volume balance
model as defined and validated by McClymont and Smith (1995), Gillies and Smith (2005) and
Gillies et al. (2007). The parameters are identified as those that cause the simple volume
balance model to best reproduce field measurements of advance (and runoff if available).
The inverse volume balance approach works well for furrow irrigation however there were
several cases where it failed to successfully estimate the parameters in this project. These
difficulties arise primarily because the volume balance method is only valid with data collected
prior to cut-off of the inflow. This limitation is compounded in the case of bay irrigation by the
relative importance of the surface roughness, the large volume of temporary storage on the
surface of the bay, and the short irrigation times compared to furrow irrigation. In these cases
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an alternative inverse solution of the more robust full hydrodynamic model was employed. This
latter model, Sisco, currently being developed at USQ based on the earlier work of McClymont
et al. (1999), allows estimation of the roughness and infiltration parameters using measurements
collected after the inflow cut-off time.
Once the relevant parameters have been determined, the IrriMATETM process employs the
surface irrigation simulation model SIRMOD (Walker, 1999) to replicate the measured irrigation
and to quantify the performance of that irrigation. It can then be used to investigate the
opportunities and strategies for improvement. SIRMOD is a proven model (McClymont et al.,
1996) that solves the full hydrodynamic equations (continuity and momentum equations) that
govern unsteady free surface flow. For this study SIRMOD III was used rather than SIRMOD II
because of its ability to accommodate a time varying inflow into the bay.
The key irrigation performance parameters calculated are the application and requirement
efficiencies and the volumes of deep percolation and tail-water runoff. Application efficiency (Ea)
is a measure of the volumetric losses occurring during an irrigation and is defined here as:
Volume applied
Volume stored in rootzone
Ea ×
= × × × (2)
Under this definition, tail-water runoff is considered to be a loss to the particular irrigation even if
not lost to the farm. It is acknowledged that tail-water is usually captured and recycled thus
contributing to the whole farm efficiency.
Requirement (or storage) efficiency (Es) is an indicator of how well the irrigation meets its
objective of refilling soil moisture deficit in the root zone is presented here as:
Soil moisture deficit
Volume stored in rootzone
Es × ×
= × × × (3)
The value Es is important when either the irrigations tend to leave major portions of the field
under-irrigated or where under-irrigation is purposely practiced to use precipitation as it occurs.
CASE STUDY RESULTS
Example – Site 1
This site at Strathmerton is located on a moderately permeable soil, predominately Group II with
some Group III at the bottom end of the bay. Inflow rate for the first irrigation was restricted by
the capacity of its unusual pipe inlet structure. Average flow rate for the trial was 4.2 ML/d but
increased throughout the trial from 3 to 4.7 ML/d as shown by the full inflow hydrograph given in
Figure 1. This was typical of the hydrographs for a number of the trial sites. The cause is not
known and may be due to variations in the level of the supply channel or to non-steady
conditions in the farm channel.
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0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
0 100 200 300 400 500 600 700 800
Time (min)
Inflow (ML/day)
Figure 1 Inflow hydrograph for site 1 irrigation 1
The analysis of the data from this site resulted in infiltration parameters consistent with the soil
type at this site and an excellent fit between the simulated and measured advance as shown in
Figure 2. To satisfy the estimated deficit of 71 mm, the infiltration characteristic suggests that
water needs to be available on the surface for about 400 min. This is clearly exceeded at the
upstream end of the bay and over much of its length resulting in over irrigation (Figure 3) and
substantial losses to deep percolation.
0
200
400
600
800
1000
1200
1400
0 50 100 150 200 250 300 350
Time (min)
Distance (m)
predicted advance
predicted recession
measured advance
Figure 2 Advance and recession curves for site 1 irrigation 1
By reducing the time to cut-off from 690 min to 600 min the application efficiency is increased
from 72% to 82%. Both tail water runoff and deep percolation are reduced. Doubling the inflow
rate from 4.2 to 8.4 Ml/d and further reducing the time to 260 min increases the efficiency to
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90%. In this case there is no deep percolation loss and the runoff is 10%. Further increases in
inflow rate deliver negligible improvements in efficiency and any further reduction in time to cutoff
leads to under-irrigation, that is, the deficit is not satisfied.
0
20
40
60
80
100
0 50 100 150 200 250 300 350
Distance (m)
Infiltration (mm)
Inf ilt rat ion
Est imat ed def icit
Figure 3 Depth of infiltration site 1 irrigation 1
For the second irrigation at this site the pipe structure was removed and replaced by a higher
capacity Padman stop. Inflow rate for this irrigation was increased to 14.7 ML/d however
application efficiency was reduced to 57% because the irrigation duration of 216 min was far too
long. Reducing this time to 125 min would have given an efficiency of 95%.
Infiltration and Hydraulic Resistance Parameters
The hydraulic resistance parameter (Manning n) varied around a mode of 0.25, from a low of 0.1
for the first irrigation of the winter pasture at the Stanhope site to a high of 0.36. These values
are consistent with other published data for bay irrigated pasture, for example, Robertson et al.
(2004) who reported a similar variation over time at a single site.
The infiltration characteristics for the trial sites are illustrated in Figure 4. Leaving aside the
winter pasture site 7, three groups of soil infiltration characteristics can be identified. The first is
the very permeable site 5. This site is typical of the coarser textured soils occurring on the prior
stream levees that show rapid infiltration and high levels of deep drainage (Lyle & Wildes, 1996).
The second group are the moderately permeable soils (sites 1 and 4) that have a characteristic
with substantial curvature over the early time (0.3 < a < 0.5) and a moderate continuing rate of
infiltration.
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0.0
50.0
100.0
150.0
200.0
250.0
300.0
0 100 200 300 400 500 600 700 800
Time (min)
Cumulative infiltration (mm)
S1-1&2
S2-1
S2-2
S6
S5
S3
S4
S7
Figure 4 Infiltration curves for each of the test bays
The final group are the heavier floodplain soils that exhibit a characteristic typical of a cracking
soil, that is, an initial rapid infiltration followed by a relatively low steady rate. For these soils the
initial rapid infiltration is very closely related to the degree of drying since the previous irrigation.
According to Robertson et al. (2004) it can be estimated as 0.75 (ET – R), where ET and R are
the evapo-transpiration and rainfall, respectively, since the previous irrigation. The term (ET –
R) is equal to the soil moisture deficit. The parameters calculated for this group of soils are
entirely consistent with those previously reported by Maheshwari and Jayawardane (1992),
Austin & Prendergast (1997), and Robertson et al. (2004).
Efficiencies, Deep Drainage and Tail-water
The calculated performance for each of the irrigations is presented in Table 2. These show an
average application efficiency of 69% (with range 46 to 86%). Tail-water runoff was 14% (0 to
36%) and the loss to deep drainage was a similar magnitude and is equivalent to a depth of 12
mm (0 to 26 mm excluding sites 5 and 7 which had abnormally high drainage losses). Site 5 is
on a highly permeable soil (sand) and only managed to achieve an application efficiency as high
as 46% because of the very high deficit of 111 mm. This site is not suitable for surface irrigation.
At site 7, the first irrigation of winter pasture, the soil was very dry and very permeable. With a
relatively low flow rate the advance did not reach the end of the bay. A much higher flow rate
would have been required to complete this irrigation. A low efficiency is typical for the first
irrigation of a season and has been observed frequently in furrow as well as bay systems (Raine
et al., 2005).
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Table 2 Summary of results from bay evaluations
Site/ Test
Measured
Flow Time Vol Applied Deficit Ea Es Runoff Deep Drain
(ML/d) (ML/d/m) (min) (ML/ha) (mm) (%) (%) (%) (mm)
S1-1 4.2 0.067 690 0.988 71 71.7 100.0 14.4 13.7
S1-2 14.7 0.234 215 1.080 62 57.2 99.3 36.0 7.3
S2-1 8.3 0.156 435 0.999 53 54.1 100.0 21.7 24.2
S2-2 7.1 0.129 443 0.841 51 63.0 100.0 6.1 26.0
S3 11.2 0.128 324 0.918 101 86.0 78.0 14.0 0.0
S4 4.6 0.108 285 0.758 65 84.9 98.5 0.0 11.3
S5 10.0 0.220 612 2.426 111 45.9 100.0 2.5 125.2
S6 7.3 0.119 529 1.007 80 79.3 100.0 14.6 6.1
S7 2.5 0.125 295 1.519 >100 54.1* 90.2 0.0 63.8
* advance did not reach the lower end of the field
In one case (S3) the irrigation failed to fully satisfy the moisture deficit, that is, Es was much less
than 100%. The infiltration curve for this site shows an initial rapid infiltration (crack fill) of 35 to
40 mm suggesting that the deficit of 101 mm estimated for this site may be incorrect. If a lower
deficit is assumed the storage efficiency will increase in proportion.
Performance Improvement
Strategies to improve the performance of surface irrigation typically involve reducing the
irrigation time and/or increasing the inflow rate (for example, Smith et al. 2005). In this study the
strategies and the potential gains vary across the sites however a readily realisable gain in
efficiency of 19% is possible and ranges from 6 to 38% for the different sites. This is illustrated
in Figure 5. In this figure, the depth ratio (depth applied to the field expressed as a ratio of the
deficit) provides an indication of the adequacy of the irrigation. A ratio greater than 1 indicates
over-irrigation and deep percolation loss. In all cases only those efficiency gains that could be
obtained without decreasing the requirement efficiency were considered. The target for the
improved irrigations is an efficiency of 100% and a depth ratio of 1, and it can be see that in
each case the result is nearer to that point. The potential gains shown in this figure typically
require a doubling of the inflow rate, that is, an increase from a mean of 0.12 ML/d/m width
(range 0.07 to 0.16) to 0.22 ML/d/m (0.12 to 0.32). The strategies for each site and the potential
for improvement are provided in greater detail in Table 3.
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0
10
20
30
40
50
60
70
80
90
100
0 0.5 1 1.5 2 2.5
Depth ratio (Applied/Deficit)
Application efficiency %
Target
Measured
Achievable
Figure 5 Measured and readily achievable application efficiencies
Table 3 Simulations of the improved irrigation events.
Site/ Test Change time only Double inflow rate
Time Saving Time Flow rate Saving
(min) ML/ha (min) ML/d ML/d/m ML/ha
S1-1 570 0.172 260 8.4 0.134 0.243
S1-2 125 0.452 * *
S2-1 300 0.310 130 16.6 0.313 0.402
S2-2 400 0.082 170 14.2 0.259 0.195
S3 280 0.124 * *
S4 * 128 9.2 0.217 0.077
S5 * 240 20.0 0.440 0.523
S6 464 0.125 220 14.6 0.238 0.169
S7 * 130 5.0 0.251 0.180
* Not a valid strategy at this site
Selection of the ‘optimum’ or preferred irrigation always requires compromise. Attempts to
maximise application efficiency will inevitably result in reductions in the requirement efficiency
(adequacy) and uniformity of the irrigation. Further different irrigators will have different
preferences in regard to minimising tail-water or deep percolation. Any recommendations will
also have to take into account the irrigators willingness and ability to work with the shorter
irrigation times required. In the present study, very much shorter times required for the improved
irrigations will only be possible through adoption of automation.
The higher flow rates required may be obtainable by either: (i) and increase in the supply rate
from the channel system, (ii) by improvements to the on-farm infrastructure to give greater
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capacities in the farm channels and structures, or (iii) reducing the width of the larger bays.
What is certain is that realising the possible improvements in performance will involve
substantial cost to the irrigator.
GENERIC SIMULATIONS
Method
A series of simulations were carried out to define the relationship between application efficiency
Ea and inflow rate. Standard infiltration curves were selected to represent the main infiltration
groups identified in the study, namely, the (sandy) levee soil, the moderately permeable soils,
and the heavier cracking type. For each of these soils the simulations considered bay lengths of
200, 400, and 600 m. A target tail-water runoff of 5% was used to ensure that all irrigations
easily reached the end of the bay.
Results
Examples of the results for two of the soils are presented in Figures 6 and 7. Clearly, the
maximum efficiencies attainable and the flow rates at which they occur are influenced heavily by
bay length as well as infiltration. It should also be noted that as flow rates increase the irrigation
on-time required decreases rapidly and the likelihood of under-irrigation (ie, Es < 100%)
increases.
To place these results in context the inflow rates from the case studies are:
· average measured flow rate 0.12 ML/d/m width (4.8 ML/d for a 40 m wide bay); and
· average flow rate for the improved irrigations 0.22 ML/d/m (8.8 Ml/d for a 40 m wide bay).
These compare to a flow of 0.53 ML/d/m (21.2 ML/d for 40 m bay) required for maximum
efficiency for a 600 m long bay on the heavy soils (Figure 6).
40
50
60
70
80
90
100
0.00 0.50 1.00 1.50 2.00
Flow rate (Ml/d/m width) Application efficiency %
200 m
400 m
600 m
Figure 6 Maximum application efficiencies for various length bays on a heavy (cracking)
soil with a 45 mm deficit
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0
10
20
30
40
50
60
70
80
90
100
0.00 0.50 1.00 1.50 2.00
Flow rate (Ml/d/m width)
Application efficiency %
200 m
400 m
600 m
Figure 7 Maximum application efficiencies for various length bays on a moderately
permeable soil with a 50 mm deficit
IMPROVEMENTS TO THE EVALUATION METHODOLOGY
At the start of this project it was recognised that the evaluation process had some limitations that
would be exposed in the application to bay irrigated pastures. Briefly these are:
1. the difficulty in measuring the runoff from a bay,
2. the relatively short on-times in bay irrigation, and
3. the difficulty in quantifying the high and time variable surface roughness.
The quality of the estimates of the infiltration parameters depends very much on the length of
time over which the data used in the estimates is collected – the longer the time the better the
estimates. The volume balance model IPARM (Gillies et al., 2007) used in the inverse solution
for these parameters can only use data collected before the inflow is cut off. In the case of a
long furrow (> 1000 m) the on-time may be as long as 12 to 18 hours and this allows great
confidence in the resulting parameter values. In this study the on times were relatively short and
frequently the advance was only three quarters of the distance down the bay when the inflow
was stopped.
Increasing the time over which valid data is collected can be achieved by two means. First is to
use a model that can use data from times later than cut-off. This is one objective of the Sisco
model currently under development at USQ and based on the simulation engine of McClymont
et al. (1999). The other is to use data collected after the advance reaches the end of the bay.
Given the difficulty in measuring tail-water, measurement of the depth of water at the
downstream end of the bay during the period of runoff could be used as a surrogate for runoff.
The new model will allow users the option of using runoff or depth.
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The surface roughness parameter is difficult to identify using advance data only. This is largely
because the effect it has on the advance is similar to that of the k parameter in the infiltration
equation. Runoff data (or its surrogate depth data) are necessary to separate the effects of
these two parameters.
CONCLUSIONS
Evaluations of bay irrigation performance were successfully carried out using the IrriMATETM
system at seven sites across the GMID. It has been shown that the evaluation process can lead
to substantial realisable gains in efficiency for individual growers. These potential gains vary
widely and the strategies to realise them also vary. However, for most the requirement will be
for higher inflow rates and shorter irrigation times. Practically this means improvements to the
supply capacity on- and off-farm and on-farm automation. The evaluation process provides the
means to set the flow rate and irrigation time for automated systems. Evaluation also provides
the means for identifying preferred capacities for farm outlets.
ACKNOWLEDGEMENTS
The authors gratefully acknowledge Price Merrett Consulting for undertaking the field
measurements, Michael Zerk, SARDI, for his assistance in the field measurements at the first
two sites, the respective irrigators for their cooperation in the provision of the field sites, and
finally the Northern Victorian Irrigation Renewal Project (NVIRP) for funding the study.