The pontiff circled the field in his bullet-proof popemobile, greeting worshippers from Jordan and neighbouring countries while they sang "yes to love, yes to peace".
Benedict urged Christians in the Middle East to play a role in seeking peace as he visited Bethany on the east bank of the River Jordan, where Christians believe Jesus was baptised.
He will travel to Israel and the occupied Palestinian territories on Monday, where he will visit Tel Aviv, Jerusalem, Bethlehem and Nazareth.
Al Jazeera's Barbara Serra, who is travelling with the pope, said: "I think there the real challenges will begin, as he enters the minefield which is the peace process, or the lack thereof, between the Israelis and Palestinians.
"Of course, what the Palestinians would want is a clear condemnation of the recent war on Gaza and of the illegal occupation of Palestinian territories.
"The pope will be visiting a refugee camp in Bethlehem which in itself is a sort of recognition of the plight faced by millions of Palestinians. But certainly a strong statement would anger Israel so I think it's unlikely to happen."
The pope is on a week-long pilgrimage to the Middle East. His main theme has been Christian-Muslim relations,
He addressed government officials and religious leaders in Amman's al-Hussein mosque on Saturday.
He said Muslims and Christians must strive to be seen as faithful worshippers of God "because of the burden of our common history" that has often been marked by misunderstanding.
Christian communities have dwindled in recent decades in the Middle East, as wars, political instability and poverty have prompted many to leave.