About 10,000 hectares of arable land was devastated in Sendai prefecture when the tsunami struck Japan last month.
Nearly four weeks after the disaster, some of the rice paddies in the area, known as Japan's "food basket", are still swamped with saltwater.
The tsunami also left behind toxic chemicals, industrial waste, oil, and heavy metals, all harmful to the soil. It could take five to ten years before the land is usable again.
The 80 million tons of debris the tsunami scattered over the landscape also includes material potentially harmful to humans.
Al Jazeera's Marga Ortigas reports from Sendai.