Confronto tra liquamazionee concimazione azotata al mais in terreno argilloso: bilancio dell'azoto

摘要

In this study the N balance approach was applied at the field scale with the aim to improve knowledge about crop N needs and fertilizer N fate in the environment. In a three-year field experiment on a silty clay soil in the Po Valley, we estimated the relative contribution of selected terms to the N balance and the amount of nitrogen unaccounted for (N_(inc) at the end of the growth season for maize that had received either urea (225 kg of N ha~(-1)), or pig slurry (225 kg of N ha~(-1)), or both of them (225 + 225 kg of N ha~(-1)). The N balance included the following terms: fertilizer N; crop N uptake; denitrification and N_2O losses; ammonia emissions; changes in soil N storage. The highest N_(inc) values were observed in the most fertilized plots. However, the results of the nitrogen balance dramatically differed from year to year, whereas only slight differences were found between urea and pig slurry treatments. In plots fertilized with pig slurry, crop N use efficiency was lower than in those with urea, mainly due to ammonia losses.