Optimization of Nitrogen in Durum Wheat in the Mediterranean Climate: The Agronomical Aspect and Greenhouse Gas (GHG) Emissions

Durum wheat (Triticum turgidum L. subsp. durum) is the most cultivated cereal crop in the Mediterranean basin, traditionally grown under rainfed conditions using conventional tillage. Agronomical practices, soil type and climate variables are known to influence crop productivity. Their interaction effect is very complex and the time in which they occur strongly affects yield and quality. The nitrogen supply, in combination with climatic conditions, is the main constraint determining the physiological performance, grain yield and quality response of wheat. In addition, the N formulation, fertilizer management, crop sequence, seasonal trends, and the supply of residual and mineralized N influence the response of wheat to N fertilizer. N fertilizer management must be optimized to prevent N deficiency in the critical crop growth period, to avoid yield and quality losses and also prevent the excessive application of N fertilizer, thus reducing the environmental impact. The split application of N fertilizer is a promising strategy that satisfies plant needs and reduces N losses through improved nitrogen use efficiency (NUE). Such a strategy can result in a remarkable reduction in greenhouse gas (GHG) emissions and the carbon footprint of Italian durum wheat, considering that the highest proportion of the total emissions deriving from N fertilizer production and its application.