The Role of Green Manure in Wheat Production on Low-Fertility Soils in Northwestern Romania

Green manuring may improve crop performance on acidic, low-fertility soils, although its effects depend on the incorporated species and mineral fertilization regime. This study evaluated the effects of five green manure crops and mineral fertilization on winter wheat during the 2021/2022 growing season at the Agricultural Research and Development Station Livada, northwestern Romania. A two-factor split-plot field experiment was conducted at a single location during one growing season (2021/2022) using three replicate blocks. Six main-plot treatments—wheat, triticale, pea, narrow-leafed lupine, oilseed rape, and a non-sown control with spontaneous vegetation—were combined with two subplot regimes: with and without combined N–P mineral fertilization. The green manure × mineral fertilization interaction was significant for grain yield (p = 0.008). Under mineral fertilization, pea produced the highest numerical grain yield (8018 ± 116 kg ha−1; mean ± SE, n = 3), compared with 6730 ± 244 kg ha−1 in the corresponding fertilized control. Without mineral fertilization, pea and lupine produced 5427 ± 187 and 5009 ± 237 kg ha−1, respectively, compared with 3419 ± 108 kg ha−1 in the corresponding non-fertilized control. Wheat and triticale green manures were associated with lower subsequent wheat yields than their corresponding controls under both fertilization regimes. Under the conditions of this single-site, single-season experiment, pea and narrow-leafed lupine were associated with favorable grain-yield responses, particularly relative to the corresponding non-sown controls. Further multi-year and multi-location experiments are required to determine the stability of these responses under contrasting soil and climatic conditions.