From Reuters, writers Silvia Aloisi and Darren Ennis explain the proposal.
The declaration said Washington was ready to mobilise $3-4 billion and wanted other partners to match that commitment to reach the $15 billion target.
"The funds...would be earmarked for investment in low income countries to implement agriculture development strategies, to finance agricultural infrastructure, land and water management, risk mitigation actions," the declaration said.
It said they would be pooled in a global agriculture and food security trust fund managed by the World Bank. It voiced concern for the impact of the economic crisis, food price volatility and under-investment in agriculture on poverty.
The United States is the world's largest food aid donor, mostly of domestically grown food bought from U.S. farmers.
The European Union has welcomed U.S. President Barack Obama's pledge for new funds, and EU Commission President Jose Manuel Barroso said on Monday the bloc would commit another $1 billion per year on top of the money it has already promised -- estimated at around $7 billion to date.
Italian Prime Minister Silvio Berlusconi, who will host the G8, said he expected the meeting to slate between 10 and 15 billion dollars for world food security. But the EU is sceptical about the need for a new mechanism, such as the proposed trust fund.
Aid campaigners are also worried about the lack of details about the funds to be pledged by the G8 summit.
"The devil is always in the detail. Is this new money? Are they including loans as well as grants, bilateral as well as multilateral commitments? The G8 needs to be absolutely transparent about what it is doing," said Oliver Buston of anti-poverty campaign ONE.