The following are case studies of growers who have improved their water mangement practices and increased their water-use efficiency as a result of participating in a RWUE program. 

• Pivots deliver benefits front and centre
• Tensiometers prove useful tool  
• Controlled traffic farming systems
• Green farming methods pay good dividends 
• Double check on moisture levels proves beneficial

Pivots deliver benefits front and centre

The Russo brothers near Childers have taken on the challenge of improving farming practices and increasing yields to maintain profitability on their highly specialised irrigated farming enterprise. Two centre pivot irrigators have played a key role. This case study, by Merv Jessen, Industry Development Officer, Irrigation Association of Australia, looks at the advantages gained through the adoption of better irrigation technology in the sugarcane industry.

The farm: Located in the Childers area near Bundaberg, the Russo brothers supply nearby Isis Central Mill. They have 700 ha, which is used for growing cane and alternative crops, including soybeans, peanuts and other break crops. Land is also leased out for horticultural production. The main soil type under the towable centre pivot is red forest. The first pivot was purchased in 2003. Another permanent pivot was installed in 2004.

Average cane production is about 110 t/ha, well above the mill average for this region. The brothers, Joe, John, Peter and Anthony, are also actively involved in a range of industry leadership roles within the community. Joe Russo is canegrowers Vice Chairman and Chairman of canegrowers Isis. John is a Councillor on the Isis Shire Council, while Peter is Deputy Chairman of the Isis Central Mill Board of Directors.

Irrigation: High-pressure travelling irrigators were the main means of irrigation before the installation of the two centre pivots in 2003-2004. Water is sourced from the Bundaberg Irrigation Scheme, which provides 2200 ML when the total allocation is available. Additional sources include two farm dams, each with 150 ML capacity, and one dam with a capacity of 600 ML. 

Bores supply additional irrigation water as required. Annual water usage is about 4.5 ML/ha when 100% of the water allocation is available.

Reasons for adopting best management practice: Peter Russo says that the main reasons for buying the centre pivots were to reduce farm labour, increase productivity and profitability and reduce repairs and maintenance on former irrigation systems (high-pressure travelling rrigators). The $20 000 financial incentive the brothers accessed through the Rural Water Use Efficiency Initiative (RWUEI) was also a major factor in making the decision to buy the pivots.

'Improved irrigation efficiency has increased our tonnes/ML since we introduced the pivots,' Peter said.

'Before, we had two winches to cover the area of one of the pivots and we have found that the pivot gives us the ability to respond better to crop needs, whereas the winches had us locked into a rotation.

'The pivot can cover the ground quicker and apply water when the cane needs it, and therefore  is better able to meet crop demand.'

The Russos say that the three major economic benefits of changing to centre pivots are labour, energy costs and increased yields.

Taking these three factors into consideration, it is estimated that the payback time is about three years, based on 2004 industry figures. This does not include the $20 000 that the RWUEI financial incentive contributed towards the cost of the pivot. 

Other benefits include a more uniform application of water, especially during windy conditions. This also contributes to increased yields.

Irrigation system performance checks: As part of the cost/benefit analysis of using centre pivots to irrigate sugarcane, the Irrigation Association of Australia carried out a detailed system check on each of the centre pivots.

Each machine is fitted with Senninger I-Wob sprinklers mounted above the crop canopy. Catch can tests showed a result of 91% CU, a good result for these machines. 

The tests showed that the results could be further enhanced by minor adjustments to the end gun settings, which would improve the distribution at the outer end of the machine.

Pumping cost comparisons were also carried out and it was found that the energy costs ranged from $20-58/ML to $24-03/ML across both pumping systems. These were based on 10 c/Kw hr energy costs.

These costs are well below the accepted benchmark figure of $40 to $45/ML often quoted when using high-pressure irrigation systems.

Irrigation management:The use of centre pivots has enabled the Russos to better manage irrigation water and respond better to crop needs.

'Under the pivots we have less runoff and we can put less water on more often,' Peter says. 

This has also enhanced the value of using an Enviroscan to make irrigation decisions. Previously, the high-pressure water winches were locked into a fixed rotation.

'There is also far less maintenance and very few breakdowns, which also contributes to the improved lifestyle benefits associated with easier irrigation,' Peter says.

'An added benefit is that the pivot will shut down if there is a problem, which is not the case with our previous high-pressure systems.'

Both machines are fitted with boom backs, which helps to reduce wheel rutting problems.

Conclusion: Overall the Russos are happy with their centre pivots and are implementing other options for lifting productivity further. These include trash blanketing and minimum tillage in a controlled traffic environment. The Russos hope that by incorporating controlled traffic into their business they can extend ratoons and make business more profitable.

 

Sourced from Irrigation Australia Journal, Winter 2007 edition Vol 22 No. 2 pg 6-7

Tensiometers prove useful tool

Dan and Shayne Cini run a 30 hectare banana plantation in the Wet Tropics area of Far North Queensland, near Innisfail. With the help of their local Water for Profit irrigation development officer they have been examining the efficiency of their irrigation system.

Bananas have a high water requirement and effective irrigation is crucial to optimum production through dry periods. Stress on plants during these periods can result in poor fruit set during that period. The Cinis initially trialled tensiometers lend to them from the Water for Profit program to assist scheduling irrigation events and durations in one of their banana blocks.

Shayne notes that 'we were able to decrease the frequency of irrigation in the cooler months and found that at times we had to increase the frequency in the hotter months, or when demand increased quickly'. 

They also improved their drip system through regular flushing of their laterals to decrease the chance of blocked emitters. This was particularly important as they use regular fertigation which requires good system uniformity so that every plant receives sufficient water and nutrients. 

Regular fertigation can also contribute to blockages if not managed properly. Tests were run with nitrate test strips to determine the optimum injection and flushing periods when fertigating and simple changes were made to their fertigation injection system to achieve this. 

The Cinis now use their tensiometers to ensure that they do not irrigate beyond the rootzone. Shayne said that 'they take the guess work out of situations such as when to irrigate after rainfall.  Not a day goes by during dry periods without me going down to check on them to see what is happening'. 

The Cinis are now happy with the management of the irrigation side of the operation, knowing that they are being as efficient as possible.

[Sourced from Fruit & Vegetable News, Feb 2006, p. 24]

Controlled traffic farming systems

Brian and Margaret Stevens have a program of continual change on their 335 ha farm at Ilbilbie, in the Plane Creek Mill area south of Mackay.

Brian’s parents started farming in the area in the late 1940s and while in partnership with his parents, Brian saw the move to green cane as the first step in a long conversion process. He sees a strong similarity between the change process involved in green cane harvesting and the long move to controlled traffic and wider rows.

'For most people the first step was to reduce tillage in burnt cane, then green cane farming was shown to reduce chemical usage and conserve moisture,' says Mr Stevens. 'The process is occurring now where the benefits of controlled traffic, wider rows and rotations are being demonstrated and slowly the technology is all starting to fit together, making conversion easier.'

This year the Stevens family has 60% of the farm converted to the controlled traffic, reduced tillage, rotation crop farming system, a process which has taken about five years. The Stevens will maintain permanent beds unless they are damaged during a wet harvest. They will not cultivate the interspace but will maintain the tracks and restrict land preparation to the bed area.

Over the last three years, the Stevens have grown soybeans to help reduce their reliance on nitrogen fertiliser. BSES nitrate and pH tests of the soil following the soybean have shown that no added nitrogen was necessary for the plant cane crops. Using soybean as a break crop has led to a 15% reduction in total nitrogen required for a crop cycle.

Each year they look at the past history, age of the ratoon and amount of water available for each block.  They then decide a target yield for each block, and apply fertiliser aimed at achieving that yield. They use a computer spreadsheet to track how well they are going. They are looking at investing in GPS technology and have an ongoing laser leveling program to improve efficiency.

Over the last three years the Stevens have seen a 4% increase in yield they attribute to their new farming system.

 

[Sourced from Australian Canegrower, 3 Oct 2005]

Green farming methods pay good dividends

Bundaberg cane grower Tom Loeskow is building the soil fertility on his farm for the next generation.  Recent soil tests confirm the success of his farming methods—primarily a return to green manure cropping. He is currently trialling a mix of field pea and turnip as a winter green manure crop.

Mr Loeskow's irrigation decisions are based on likely return on investment. As water is a limited resource he concentrates on blocks most likely to produce the greatest return. He gives his plant and first ratoon crops highest priority when making irrigation decisions. Different soils receive different treatments. The red soils also receive favoured treatment due to their inherent productivity and the investment in trickle tape. Some soils respond to deep ripping of the interrow space because compaction of the interrow reduces the water infiltration and water holding capacity of the soil.

Mr Loeskow has also developed a business plan to maximise potential savings.

[Sourced from Australian Canegrower, 11 July 2005]

Double check on moisture levels proves beneficial

Bundaberg melon growers Mick and Ron Martens recently discovered the benefits of having two forms of moisture monitoring equipment installed to assist them with irrigation scheduling.

After purchasing a diviner three years ago, the Martens brothers set out to gain greater insight into the watering requirements for the melon and pumpkin crops they grow in rotation on their 80 hectare cane property.

With assistance from the Water for Profit team they used three sets of jet-fill tensiometers to double check the moisture levels being recorded by the diviner. While the diviner readings were proved accurate, they decided to retain the tensiometers as a continuing check process. This was a wise decision that helped them resolve a problem later in the season.

Readings from the diviner showed everything was normal, but Mick and Ron had noticed a lack of vigor and spread within the foliage of a melon crop. The tensiometers installed in that block showed a significantly different picture. Investigation led to the discovery that a hole in the trickle tape was causing excess water to be applied to the area directly around the diviner tube and was affecting readings. The hole was fixed and the diviner moved. Problem solved at an early stage. 

[Sourced from Fruit & Vegetable News, Jan 2007, p. 24.]