Effects of sowing date and nitrogen applications on the energy efficiency of facultative wheat (Triticum aestivum L.) in a Pannonian environment

Energy efficiency analysis provides a deeper understanding of non-renewable energy dependent cropping systems. In this study, we examined the crop yield and energy efficiency of facultative rainfed wheat (W_W - winter wheat, W_S - spring wheat) and mineral nitrogen (N) fertilization (0, 50, 100, 150, and 200 kg N ha^-1) in two growing seasons 2019/20 and 2020/21 in Central Europe. W_W out performed W_S significantly overall (2019/20: +30.3 to +47.9 %; 2020/21: +18.9 to +37.3 %) in terms of energy efficiency indicators. The impact of N fertilization on energy efficiency was minimal, largely due to one dose application of mineral N fertilizer. The highest estimated net-energy output (NEO) was observed at 160.2 kg N ha^-1, which may not sustainable for this pedo-climatic region due to potential N emissions risks. Zero N fertilization showed best performance in terms of energy use efficiency (EUE), energy intensity (EI), and energy productivity (EP). The ERG z-score, which combines NEO and EUE into a single bi-dimensional indicator, indicated an optimal N fertilization level of 72.0 kg N ha^-1.