Minimise market conflict
Best cane farming practices in the Burdekin River Irrigation Area
Paper presented by Vin Sorbello
Working and managing sugar cane lands in the Burdekin River Irrigation Area in many regards is the same as growing sugar cane in any area. Certain principles have to be adhered to. However, we do have some distinguishing characteristics which have led to our having to adopt different management and work practices to achieve the desired result.
As a new cane grower in the Burdekin River Irrigation Area the two most prominent features I have had to contend with are the combination of soil types and method of water delivery to the farm boundary.
SOILS
With the two predominant soil types ie the sonic duplex and cracking clays the greatest difficulty is that very often they have to be worked in unison and yet they have very different behavioural characteristics. The cracking clays retain moisture longer than do the duplex soils so invariably one part of a drill is ready to work and the rest is still too wet. Logically the general response to this has been to try cultivating at the inbetween stage ie when the duplex soils are drier than usual
and the clays are still slightly wet.
One characteristic both these soils share that aids this cultivation method is that since they both have clay sub layers, only the top 75mm to 100mm will dry out enough to work up. Below this is still mud so shallow working is the order of the day and lends itself to cultivation at the previously mentioned inbetween stage.
The awkward cultivating nature of this soil combination also lends itself to the minimum tillage regime which fits in well with the larger than average size of these farms. It is also my belief that there will be a growing trend toward stool splitting as a fertiliser application technique. This is a technique whereby fertilizer is applied to the centre of the stool but more significantly it can be done immediately after harvesting prior to irrigation and therefore prior to when the above mentioned cultivation difficulties arise.
The B.R.I.A. soils are low in all of the major applicable elements N P K S but the costs of their application is comparable with most other areas in the state. I do think however we have some way to go to discover the right nutritional mix that applies to our area.
IRRIGATION
Perhaps the greatest adjustment that has to be made, (certainly by those of us who are used to irrigating from natural sources within our own properties ie streams or underground supplies), is to the different circumstances that apply when irrigating from a man made scheme which stores water in a dam and supplies it to the farm boundary through a channel system which has to be shared with other farmers. When irrigating from an unregulated natural system nature is the scheme manager. In other words, you can generally please yourself about how, when, where or why with regard only to the natural constraints that apply and to nobody else. But water from a man made scheme suddenly becomes a resource which has to be managed to ensure, that
everyone gets their share, that they get it when it's needed, that it is to be used efficiently and managed so that it does not become an environmental hazard which will jeopardise the economic
sustainability of the operation.
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The Burdekm River Irrigation Scheme is still in its infancy with by far the majority of the scheme being applied to sugar cane which is exclusively irrigated by the furrow method. The scheme managers and irrigators are still coming to terms with just how much co-operation it takes to ensure that everyone gets their entitlement. It has become obvious the scheme managers ie the DPI Water Resources have underestimated just how much and how often a cane crop needs water for optimum results. On the other hand the irrigators have experienced problems coming to terms with water ordering and scheduling. While there is some way to go to solve these problems, I am happy to say that all parties are endeavouring to work together to ensure that everyone does get their share and it is delivered when it is needed.
Once the water is at the farm boundary ready for use I believe the greatest feature of a B.R.I.A.
farm becomes apparent. Because of the generally superior farm design, the average row length of these farms is about 700m therefore it takes substantially less furrow irrigation equipment to water a hectare than it does anywhere else. Row lengths of lOOOmt are common with some row lengths reaching up to 2000mt. This also means of course substantially less labour is required to irrigate that hectare. I would even go so far as to say there is less to total equipment and labour required to irrigate an average lOOha B.R.I. A. farm than any average 45ha fully irrigated cane farm anywhere else.
As previously mentioned, with a finite amount of water available from a dam efficient use of the water that is available becomes a very important management issue. One factor that becomes important is to ensure that the water requirements of the crop are known so that only the required amount is applied at the right time. In conjunction with the B.S.E.S. neutron probes have been utilised to determine in various soil types just what a cane crops water requirements are. These results have then been correlated to an evaporation plan whereby a farmer can schedule his irrigation times to correspond to a crops water needs. This ensures water is not wasted by watering too often or the crop does not suffer by watering too late. With the B.S.E.S. we have also been able to establish that on these soils the plant water use is about 75% to 85% of the water that is applied. Be assured however, research will continue to try to raise this figure as high
as possible.
Water wastage through runoff also becomes an important issue. Because of the clay nature of these soils good drainage is crucial, however runoff water is too valuable and can be a danger to the local ecology if allowed to go off farm. Water recycling, whereby all runoff water is collected and pumped back on to the farm is becoming more widely used. The advantages here are several.
It ensures any nutrients or diseases are kept on farm and not released into the environment so the local ecology remains unaffected. Runoff water doesn't have to be paid for again. A recycling system will also allow for some water harvesting to occur from natural rainfall which is also free of charge. This takes some pressure off the supply from the system in the first place. At this point in time some 30% of farms have recycling systems with the number growing rapidly. Perhaps the reason why this figure is not higher at this time is because the scheme is not yet fully developed and since it began a few years ago the annual announced allocation has not been below 125%. I think some have been lulled into a false sense of security but as the scheme develops and more pressure is put on the supply of water it will become obvious that a recycling system for individual farms will be a useful management tool. It is my belief that we should be aiming for very little if any water to find its way out of the entire irrigation area.
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Perhaps the most feared words in any irrigation system are "underground water table". In this regard the Gods were smiling on the Burdekin by giving us the ability to pump from the underground and hence have some influence over the water table. Much has yet to be learned on just how to manage this aspect of the scheme but one advantage that can be used on farm is mixing saltier ground water with very pure river water to improve water quality for cropping.
Underground water table management will in time become probably the single biggest ongoing management issue after the development phase has been completed.
In summary the features of size and layout, soil types and availability of water from the Burdekin dam plus bang situated in an ideal sugar growing location make these farms equal to anything in the state.
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