Simulation of nitrogen losses in sugar beet production in various production systems in Khorasan

Nitrogen is one of the most important nutrients in crop production, but it's losses to the environment is harmful. The SUNDIAL model (simulation model of N dynamics in the soil) was used to quantify the cycle of N and it's losses in different production systems of sugar beet (Beta Vulgaris L.) in former Khorasan province, east of Iran. The data were collected from traditional, semi-mechanized and mechanized production systems in 26 regions of 10 geographic areas of Khorasan (Northern, Razavi and Southern Khorasan provinces) to be used in the model as inputs. Results showed that the total N loss from the soil profile in traditional, semi-mechanized and mechanized systems did not differ significantly and were 50, 41 and 45 kg N ha-1, respectively. In average, 59% of total N loss occurs as gaseous losses and 41% as leaching. The most part of the gaseous losses in traditional system occurs via denitrification (63%), but in semi-mechanized (75%) and mechanized (82%) systems volatilization was dominant. The key finding is that while various systems of sugar beet production are similar with respect to N loss per hectare, they are different with respect to N loss per ton of crop yield. The average of N loss in traditional system was significantly more than other systems in terms of kg N ton-1. This implies the possibility of reducing N losses and its environmental effects thorough improving crop management.