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New Generation OVERSEER® 6 Breaks New Ground in Nutrient Budgeting

27th September 2012

The nutrient budgeting software OVERSEER® is proving to be an excellent resource for farmers and growers, and increasingly regional councils, making it a valuable tool at a time when farming within environmental limits is becoming increasingly important.

Use of OVERSEER® has expanded to the point where it has enabled nutrient budgeting to be rolled out to virtually all dairy farmers and there has been a good start made with sheep and beef farmers as well, says Dr Philip Mladenov, Chief Executive of the Fertiliser Association of New Zealand.

“A major upgrade of OVERSEER® has just been released, which has added to its effectiveness. There is nothing else in the market approaching OVERSEER® in terms of its sophistication,” he says.

“We have to be careful that we manage its development so that it continues to add value by supporting profitable farming within environmental limits.”

He says that as OVERSEER® has come into common usage, expectations of what it can do have rapidly risen. In addition, new science is continually becoming available. It is for these reasons that successive upgrades have been required.

“This sixth and latest generation, released in August, has addressed a range of matters to achieve greater utility.” These include improved definitions of farm block types and stock classes. It provides milking shed feeding and feed pads as two separate options and enhanced input requirements for fertiliser, supplementary feed, irrigation, effluent management and nitrification inhibitors. There are improvements to the fodder crop component and, most importantly, it has introduced a more sensitive drainage model.

“A very significant upgrade to the arable sub-model was introduced in an earlier version and this has been carried through and better integrated into the new model. Many of these innovations are designed to better represent the increasing range of farm systems.”

One of the key intentions of the upgrade has been to improve modelling of particular farming types or local conditions, he says. “As a result of requirements in the Canterbury region, for example, the model’s drainage component has been improved to achieve more reliable estimates on shallow and stony soils which drain quickly and where there is growing use of irrigation.”

Dr Mladenov says that as a result of these types of changes, OVERSEER® has become a highly advanced tool. “Although, as is typical for sophisticated software, it is still a work in progress.”

DairyNZ’s Strategy and Investment Leader for Productivity, Dr Bruce Thorrold, says the dairy industry has supported the development of OVERSEER® as it is a useful guidance tool for the industry.

“We support OVERSEER® for farm management decisions when it is used by people who are trained and competent in its use,” he says.

Dr Mladenov agrees that OVERSEER® is an important guidance tool and warns that it has to be seen for what it is.

“OVERSEER® was designed to model nutrient movements and losses in a variety of farming systems – not specify exact amounts in every situation. It is an important distinction.”

“For example, there has been pressure to incorporate daily timestep data for rainfall measurements, whereas OVERSEER® currently operates on monthly timesteps. Daily timesteps would add enormous complexity with little prospect of improved outcomes. The reality is that rainfall is unpredictable and can only really be understood over long-run averages.”

“What OVERSEER® does exceptionally well is provide for sound farm management decisions using science-based estimates of nutrient cycling within the farm system, including the amounts, on average, taken up by produce or lost from the root zone. It enables scenarios to be modelled to find the best management options,” he says.

Dr Mladenov recognises there is a lack of research available to determine the fate of nutrients leaving the root zone and entering water bodies, something agencies regulating waterways are interested in. But he says OVERSEER® is neither able nor has it been intended to model the fate of those nutrients beyond the root zone or the farm boundary.

Meanwhile, further advancements in the support around OVERSEER® are currently in development. These will include improved training in its use and certification of those involved in providing advice to farmers.


A joint venture between the fertiliser industry, AgResearch and the Ministry for Primary Industries (MPI), OVERSEER® nutrient budgeting software was first released in the early 1990s and has received some $15 million of investment over the years. It is available free to users.

For further information:

Philip Mladenov
Chief Executive
The Fertiliser Association of New Zealand

Amanda Duncan
021 487 954

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