Determination of hay yield and nitrogen use efficiency in oat(avena sativa L.) and common vetch(vicia sativa L.) mixture

The sustainability of the livestock sector is directly dependent on the production of sufficient and high-quality forage. The increasing demand for high-quality feed, the reduction of pasture areas, and the limited cultivation of forage crops have led to a growing interest in mixed cropping systems. In such systems, the significance of cereal-legume intercropping is particularly evident due to the nitrogen-fixing ability of legumes and the benefits that cereals derive from this process. This study was conducted over two consecutive vegetation periods (2022–2023 and 2023–2024) under the conditions of the central district of Bilecik province, aiming to determine the dry matter yield and nitrogen use efficiency of oat and common vetch grown alone and in 50:50 mixtures, with different nitrogen fertilizer doses. The oat cultivar used as the experimental material was Chekota, and the common vetch cultivar was Kubilay 82. Three different nitrogen fertilizer doses (0, 6, and 12 kg N/da) were applied to the sole crops and their 50:50 mixture, and the experiments were established in a randomized complete block design with three replications. In the study, plant height, dry matter yield, crude protein yield, ADF and NDF ratios, nitrogen use efficiency, physiological efficiency, recycling efficiency, and some nutrient contents were determined. The dry matter yield values ranged from 382.7 to 1420.5 kg/da on the two-year average. The highest dry matter yield was obtained from the 50% oat + 50% common vetch mixture with 6 kg N/da application. On a two-year average, crude protein yield, ADF, and NDF ranged from 71.64 to 229.38 kg/da, 31.5% to 36.4%, and 49.7% to 68.8%, respectively. Nitrogen use efficiency ranged from 4.1 to 51.7, physiological efficiency from 314.0 to 2288.8, and recycling efficiency from 1.05% to 3.73%. Analysis of the data indicated that the 50:50 oat-common vetch mixture plots with 6 kg N/da application yielded the highest results in terms of dry matter yield, crude protein yield, nitrogen use efficiency, physiological efficiency, and recycling efficiency. Mixed cropping provided better results in yield and quality compared to sole cropping, and applying 6 kg N/da was found to be the most effective rate in terms of yield, economic return, and environmental sustainability. In conclusion, cultivating oat and common vetch in a mixture and applying 6 kg N/da was identified as having significant potential for sustainable forage production and nitrogen management.