Coonan exit opens way for ex-Howard aide - if he wants it

Delivering her retirement speech today, Senator Coonan will urge more transparency in foreign investment, especially from China, and warn that agricultural land should be protected in managing the mining boom. Senator Coonan, 63, was assistant treasurer and later communications minister in John Howard's government. In 2006-07 she was deputy government Senate leader. She was an opposition frontbencher in 2007-09.

It is understood the timing of her decision has been influenced by a family illness.

A Senate vacancy does not trigger a byelection the party of the retiring senator nominates the replacement, who is then ticked off by the State Parliament. Liberal sources said if Mr Sinodinos, who is president of the NSW Liberal Party, wants the seat he will get it.

Senator Coonan will tell the Senate today that Australia's challenges include getting a "more transparent and coherent approach towards foreign investment, including from China". She will say there should be a better system to balance the interests of miners and farmers in coal seam gas mining.

While stressing the importance of foreign investment, she will say that "many Australians have become uneasy about whether such investment for mining purposes, most particularly coal seam gas exploration licences, will affect prime agricultural land, and to question the impact this might have on Australia's land use and future food security. These concerns are not without foundation".

Although land use issues are primarily state responsibilities "surely it should not be beyond our collective wit as a nation to devise a framework which maps and designates prime agricultural land that should be conserved in the national interest but not so as to discourage forms of foreign investment that will allow the responsible management of multiple land use".

Striking the right balance will require hard decisions and possible recompense for land owners, she will say: "There cannot be too many more compelling national priorities than balancing protection of agricultural land as a key part of ensuring Australia's food security, with managing the mining boom."

Senator Coonan will work in the corporate world in her post-political life.

Mr Howard last night said Senator Coonan had "handled the difficult communications portfolio with flair and handled complicated Treasury issues with much skill".