Nitrogen fertilizer application of commercial soybean farms and its impact on soybean yield and nutritional composition in Hungary

Nitrogen fertilizer application of commercial soybean farms and its impact on soybean yield and nutritional composition in Hungary

Ildiko Edit Tikasz– Zsuzsa Molnar– Edina Varga

Institute of Agricultural Economics (AKI), Hungary

Soybean, due to its biological nitrogen (N) fixation via nodule bacteria, can meet its N requirements from the air and the soil. Several studies report that excessive N fertilization may negatively affect plant productivity and soil condition. The amount of N applied by Hungarian soybean farmers varies widely and sometimes exceeds the recommendations significantly. This study evaluates the effect of increased N application on soybean yields and nutritional quality. Unlike similar studies, the assessment relies on data collection from commercial soybean farms instead of field experiments. Soybean samples along with the applied agrotechnological information were collected from 58 Hungarian farm enterprises in 2021 and 2022. The total number of samples was 526. The nutrient composition of grains was determined by Near Infrared (NIR) Spectroscopy. Soybean yield and nutritional composition were assessed at different N fertilizer ranges (<20, 20-50, >50 kg/ha) by taking soil quality (week, medium, good) conditions and growing season length (120-140, 140-150, >150 days) into account. Yield average value was highest (2.893 t/ha) at 20-50 kg/ha N-level, 10.2% above the yield average at <20 kg/ha and 15.1% above the yield average at >50 kg/ha N-levels. The coefficient of variation (CV) of yields in each N categories were extremely high (CV>32%). The average values of crude protein (CP), digestible lysine (SID Lys) and crude ash (CA) varied significantly among the N-ranges, in contrast to crude fibre (CFi) and crude fat (CF). The variability of nutrient parameter values was low (CV <10%) in each N-levels, except for CFi where the CV value was 12-14%. Soil quality and the length of growing season showed moderate effect on all parameters. Understanding the practice of N application and studying its effects helps farmers to identify the factors that contribute to cost-effective, ecologically sustainable, and high-quality soybean production.

Keywords: commercial soybean farms, grain nutritional component, nitrogen fertilizer application, NIRS analytics, yield

Acknowledgements: We thank for the Association of Hungarian Soybean and Protein Crop Producers for conducting the collection of samples and farm data, as well as for providing NIRS analytics.

This paper was supported by European Union's Horizon Europe research and innovation programme under grant number 101060481 – FOODCoST