Abstract
In previous studies, a system consisting of catch crop cultivation and lactate fermentation was proposed in order to reduce greenhouse gas emission and nitrate infiltration from agricultural field. The system also has aims of recovering nutrient and producing lactate from catch crops to gain profitable products. In this research evaluation of the amount of greenhouse gas emission, nitrogen load to water environment and break-even point of introducing the lactate fermentation system of catch crop were conducted. As a result, increased amount of greenhouse gas emission from the whole system is larger than the decreased amount of N2O gas emission from agricultural field by catch crop. Most of the nitrogen load from agricultural fields cleaned up by catch crop is discharged as waste water from lactate production process. This means non-point source pollution in the agricultural fields is transformed to point source pollution through the system. Evaluation results showed the system could help to reduce the nitrogen load on water environment using advanced wastewater treatment. From the evaluation of the production cost, we found that nutrients extracting system in the previous stage of lactate fermentation is relatively advantageous than other systems. It was found that the break-even point of the system is greater than 105tDryWeight of catch crop, which means it is greater than 18ha of cultivation area of catch crop.
