The call was made on World Food Day as rich and poor capitals marked the occasion with actions large and small.
In Rome, Pope Benedict XVI appealed for solidarity as the key to eradicate poverty and underdevelopment.
Local communities "must also be involved in the choice and decisions that concern the use of their territory, because arable land is increasingly directed to other uses to the detriment of the environment," the pontiff said.
The message was read by the Holy See's permanent observer at the UN's Food and Agricultural Organization (FAO).
According to the FAO, wealthy nations have fallen short in helping some 850 million hungry people around the world.
Foreign aid for agriculture and rural development has declined from an average of nine billion dollars (seven billion euros) in the early 1980s to less than five billion dollars in the late 1990s, according to the FAO.
"Increasing the volume of public investment in agriculture but also making it more effective are of absolute necessity," FAO head Jacques Diouf said Monday, recalling that the World Food Summit in 2002 adopted as its core objective reducing world hunger by half before 2015.
In Kinshasa, the Democratic Republic of Congo's outgoing Agricultural Minister Constant Ndom Nda Ombel echoed Diouf's appeal for greater agricultural investment.
"Investing in agriculture can be justified in that it remains the most certain source not only of food but also of revenue and employment," the minister said on Congolese radio.
In drought-prone Afghanistan, officials handed tools and fertilizers to farmers during a ceremony in Kabul.
While in Bangladesh, a bleak report published Monday by the UN World Food Programme found 15 percent of the rural population suffered from chronic hunger.
Richer countries also marked the day with ceremonies recalling the plight of the poor.
Charities in Brussels and Santiago de Compostella, Spain, erected giant hourglasses as reminders of the urgency of hunger and malnourishment, which primarily affects rural areas.
"That is where it is most critical to provide food and employment – the seed planted by a farmer leads to a flourishing agribusinesses that pay taxes, and help build rural schools and roads," Diouf of the FAO said.
"Agricultural development is the first step of a long-term sustainable economic growth."
The theme for World Food Day 2006 reflects these priorities: "Investing in agriculture for food security so that the world will profit."
Diouf said that there has been a significant revival in lending and other actions promoting agriculture, including debt forgiveness programmes.
"But much still remains to be done and innovative actions are welcome," he said.
The FAO -- which has disbursed more than 80 billion dollars in funding for agricultural project to 165 member nations over four decades -- is today promoting "profitable partnerships" between private and public sectors.
"This means finding new ways of bringing together producers -- small farmers and cooperatives -- with agribusiness and governments to create profitable ventures," he said.
During the ceremonies Monday, Cuban pianist Chucho Baldes was named the FAO's "goodwill ambassador."