Abstract
In nitrate vulnerable zones (NVZs), site-specific techniques are needed to match N availability with durum wheat (Triticum turgidum subsp. durum Desf.) requirements. Enhanced-efficiency fertilizers can improve efficient N supply and reduce leaching, contributing to sustainable agriculture. Two-year field experiments were carried out at two Mediterranean nitrate vulnerable zones in Central Italy (Pisa and Arezzo) to study the effects of nitrogen sources, timings, and application rates. The trial compared: (i) three N sources for the first topdressing application (urea, methylene urea, and urea with the nitrification inhibitor DMPP); (ii) two stages for the first topdressing N application (1st tiller visible—BBCH21 and 1st node detectable—BBCH31); (iii) two N rates: one based on the crop N requirements (Optimal—NO), the other based on action programme prescriptions of the two NVZs (Action Programme—NAP). Grain yield and yield components were determined, together with N uptake. The results showed that: (i) grain and biomass production were reduced with NAP at both locations; (ii) urea performed better than slow-release fertilizers; (iii) the best application time depended on the N source and location: in Pisa, enhanced-efficiency fertilizers achieved higher yields when applied earliest, while for urea the opposite was true; in Arezzo different N fertilizers showed similar performances between the two application timings. Different behaviors of topdressing fertilizers at the two localities could be related to the diverse patterns of temperatures and rainfall. Thus, optimal fertilization strategies would seem to vary according to environmental conditions.
Highlights
Nitrogen (N) is a major macronutrient that often limits plant growth
N fertilization has environmental impacts associated with nitrate leaching, eutrophication, and global warming, due to the emission of nitrous oxide gases [1]
In Nitrate Vulnerable Zone (NVZ), farmers must follow a range of measures, including controlling the timing and quantities of fertilizers applied to the land [2]
Summary
Nitrogen (N) is a major macronutrient that often limits plant growth. Crop yield and quality depend greatly on extensive inputs of fertilizer nitrogen for sustainable and profitable crop production. N fertilization has environmental impacts associated with nitrate leaching, eutrophication, and global warming, due to the emission of nitrous oxide gases [1]. To prevent and reduce water pollution by nitrates from agricultural sources, the European Union (EU) introduced the Nitrate Directive (ND) (91/676/EEC). They are a set of actions, defined at the regional level, obliging the member states to designate areas vulnerable to nitrate pollution (nitrate vulnerable zones—NVZs). In NVZs, farmers must follow a range of measures, including controlling the timing and quantities of fertilizers applied to the land [2]
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