A NATIONAL foreign ownership register for agricultural land and water would allow a more informed debate on the issue.

That's the opinion of the National Farmers' Federation.

Along with the Victorian Farmers Federation, it has lodged submissions on how the register should be established and what it should cover.

The NFF wants to see a comprehensive register to document and review foreign investment in agriculture, land and water access entitlements.

"This register should be a post-acquisition recording system to document actual transactions (including subsequent sales) rather than just proposals that may or may not proceed ... and give a more accurate picture of current foreign ownership of Australian agricultural land and emerging investment trends as information builds up over time," its submission said.

The NFF wants the register to apply to sales in which 15 per cent or greater cumulative interest is held by foreign entities in an agricultural asset that generates an actual or "imputed" revenue stream and includes land banking and water access entitlements.

"The impact of this (and any new) investment should be monitored to ensure that it does not result in negative impacts on the market via price manipulation or market power."

The VFF agrees with the 15 per cent threshold for foreign ownership in the case of a strictly commercial entity, without government links.

But it has called for all entities with any sovereign ownership to be subject to the register, regardless of level of foreign government interest or control.

And it wants the threshold trigger for assessment by the Foreign Investment Review Board of a purchase of agricultural land or water by foreign persons or enterprises to be reduced from $244 million to $5 million.

VFF president Peter Tuohey said a register would give people a better understanding of who was buying what in different regions and how that might impact on communities.

"It's probably more important in Victoria than the other states because our farms are generally smaller family farms," he said.

Commercial Property Profiles agent Rex Phillips, who promotes Australian farms for sale to overseas buyers, said a register would be a waste of time and would not deter buyers.