Former National Party leader Barnaby Joyce, also the former agriculture and water minister, will open the event at Longerenong at 11am on Tuesday.

Now special envoy for drought assistance and recovery, Mr Joyce told the Mail-Times he would visit the event for about three hours and would tour the site with outgoing Mallee MP Andrew Broad and Nationals Mallee candidate Anne Webster.

"I'll be talking to farmers about the workings of current programs including one of the big bug bears - the Farm Household Allowance - and also access to drought concessional loans and how access to the regional investment corporation can be improved," Mr Joyce said.

"I'd also like to see where exactly farmers are with their cropping rotations and stock. Is there any prospect of a crop there for winter, is there any profile of moisture?"

Mr Joyce said he wanted to discuss the "threat" of reopening the Murray-Darling Basin Plan. 

A South Australian Royal Commission in January called for a complete overhaul of the scheme and accused federal officials of "maladminstration" for ignoring the potential effects of climate change. 

Field days manager Murray Wilson said a committee member had invited Mr Joyce to attend.

"We don't have official openings every year, so we certainly like to get high-profile people to do them when we do," Mr Wilson said. 

Federal Agriculture Minister David Littleproud officially opened the 2018 field days while former Prime Minister and then Opposition Leader Tony Abbott opened the 50th annual event in 2012.

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