NSW and Western Australian farmers are leading the spending splurge on new tractors with national sales surpassing 15,500 in the past 12 months.
Executive director of the Tractor and Machinery Association of Australia Gary Northover said current sales volumes hadn't been seen since 1984.
National new tractor sales soared 19 per cent in April compared with the same month last year, he said.
Mr Northover said signs had emerged of a "flattening of the curve" in April with buying activity in Victoria similar to levels in the corresponding month last year while sales fell in Queensland (down five per cent) and South Australia (down 14pc).
Despite the softening in demand during the month, Mr Northover said year-to-date sales for both Victoria and Queensland were still strong, up 32pc and 40pc respectively.
NSW farmers - buoyed by favourable weather conditions, good livestock prices and a bumper grain harvest - lifted their tractor purchases by 73pc in April compared with the same month last year. NSW sales are now up 95pc year-to-date.
Sales in Western Australia lifted by 20pc and are now 58pc higher year-to-date.
Tasmania's sales climbed 7pc in April.
Mr Northover said all performance categories had enjoyed rises again in April with the under 40 horsepower (30 kilowatt) range up 24pc, pushing sales 55pc ahead for the year so far.
The 40-100hp (30-75kW) range jumped 33pc (58pc year-to-date), the 100-200hp (75-150kW) category rose 6pc (38pc year-to-date) and the large 200hp (150kW) plus range enjoyed an 18pc lift, pushing sales 70pc ahead for the year.
Mr Northover said the order season for combine harvesters was now well underway with dealers reporting strong demand for what is shaping as another big harvest season later this year.
Sales of headers in the past 12 months had gone past 650 units, up from 530 during the previous year.
"Baler sales dipped for the month but are still up 34pc on an annualised basis and sales of out-front mowers were again strong and remain 32pc ahead of the same time last year," he said.
Mr Northover said the level of demand in the farm machinery market continued to surprise with many suppliers reporting buyers bringing forward buying plans to take advantage of the federal government's tax write-off incentives.
"The challenges in meeting this demand are showing no signs of abating. Shipping and port clearance delays are having a significant impact on delivery times," he said.
"We are receiving reports of a more than doubling of shipping times being compounded by a shortage of containers and bottlenecks at Australia's ports.
"As a result, suppliers are having great difficulty guaranteeing delivery times which is hampering confidence in the supply chain.
"To compensate for these delays, forward orders are now sitting at levels well above what would be considered normal, posing a risk of oversupply in the event of a slowdown in demand."
Meanwhile, the keynote speakers at the TMA's annual conference on July 20 will include ACCC deputy chairman Mick Keogh and VFF president Emma Germano.
Ticket sales have now opened for the event at Melbourne's Hyatt Essendon Fields.