Greenhouse Gas Emissions and Yield of Durum Wheat Under Organic and Conventional Fertilization in Three Texture Classes

Durum wheat (Triticum turgidum subsp. durum), though less widespread than soft wheat, is crucial in Mediterranean countries. Agriculture significantly contributes to global climate change by emitting greenhouse gases, particularly nitrous oxide, which accounts for about 6% of global warming because of its long atmospheric lifetime and heat-trapping capacity. Soil fertility is influenced by the interplay of its physical, chemical, and biological properties, which, in turn, affect the production of nitrous oxide (N2O), a potent greenhouse gas. The yield-scaled N2O emission index, which measures N2O emissions relative to crop yield, is used to develop sustainable agricultural strategies. Our study aimed to compare the effects of organic vs. conventional fertilization on durum wheat yield and N2O emissions across three soils differing in texture. The study was carried out from autumn 2020 to spring 2021 in Portici (Naples, Italy). A factorial combination was applied, involving three different texture classes (clay, sand, and loam) and four fertilization strategies (no fertilization, compost, digestate, and mineral fertilization). Our results highlight that in sandy soil, wheat yield reached its highest values, particularly under digestate fertilization (+74.5%) and, interestingly, with lower cumulative N2O emissions (−16%). However, in sandy soil, the protein content of kernels was lower, similar to that recorded for the fertilization with digestate.