The uptake of nitrogen biologically fixed by faba bean by cereals grown as succeeding crops

In sustainable plant production, the cultivation of legumes is crucial as it reduces the need for mineral fertilizers by fixing nitrogen (N), which is then available to succeeding crops, mainly cereals. While the effects of legumes as precrops on the first following crops have been relatively well documented, their longer-term impact on the productivity of subsequent crops in the rotation remains poorly understood. This research aimed to determine the amount of N fixed (% Ndfa, 15 N isotope dilution method) by faba bean ( Vicia faba L.) and taken up by the grains and crop residues (roots and straw) of two succeeding plants. Two three-year cycles were carried out (2017–2019, 2018–2020) with the following crop sequence: faba bean/wheat-wheat-triticale. The % Ndfa in faba bean residues was found to be 78.1–79.4 %, depending on the year, which gave 29–43 kg ha −1 of N introduced into the soil from the total N amount of 38–55 kg ha −1 . With wheat residues, 28–35 kg ha −1 of N was incorporated. The year of the experiment significantly affected the yield and N parameters of cereals at maturity, mainly for the first crop after precrop. Significant changes were observed between precrop treatments. N uptake by cereals from faba bean residues (N recovery) was significantly higher than that from wheat residues, both in grains and crop residues of the succeeding crops. Cereal yields, N and macronutrient (P, K, Ca, Mg) yields were improved or unchanged by using legumes in the crop sequence, depending on the plant part examined (grains or straw), year and crop. N derived from legumes is important for the productivity of subsequent cereals, mainly for grains, but also for crop residue yields: higher yields can be achieved as compared to non-legume treatment. The findings may be useful with regard to optimizing crop rotation strategies and sustainable agricultural practices.