Evaluation of erosion productivity impact calculator (EPIC) model for nitrogen losses in rice paddy of Thailand

Abstract

Rice fields are commonly characterized by flooding conditions and high percolation rate. Nitrogen (N) is the most important nutrient for rice yield and is required in large quantities. In this article, the Erosion Productivity Impact Calculator (EPIC) 0509 version was used and was run using i-EPIC (interactive EPIC) interface, to validate this version and evaluate N losses in mineral rice soils. The results indicated that N losses of rice soil in terms of N loss in sediment, nitrate (N03) loss via runoff, NOgloss in subsurface and NOg leaching. The results revealed that the northern region of Thailand had the maximum average of 9.58 kg ha-1 during the major rice season, followed by the central, eastern, western, northeastern and southern regions, respectively. In the second rice season, NOg loss in the western region had the maximum average of 25.52 kg ha-1, followed by the northern, central, eastern, northeastern and southern regions, respectively. In terms of N pool (humus mineralization, slow humus N pool, passive humus N pool, total N pool) the eastern region had the maximum average of 4,475.33 kg ha-1 during the major rice season, followed by the central, southern, northern, northeastern and western regions, respectively. Whereas, the second rice season found that the eastern region had also the maximum average of 6,909.03 kg ha-1, followed by the central, southern, northern, northeastern and western regions, respectively. Furthermore, EPIC-simulated hydrology found that precipitation, runoff, percolation and soil temperature share a positive relationship with major rice yield. © 2014 Knowledgia Review, Malaysia.