The intercropping of two or more crop species on the same piece of land at a given time has been hypothesized to enhance crop yield stability. To address this hypothesis, we assessed the grain yield stability of various barley-pea and wheat-faba bean mixtures grown in seven experimental field trials (locations) across Europe during two years with contrasting weather (2017 and 2018). Three different yield stability measures were used, all based on the expected yield variability of the mixture components grown as sole crops, and the corresponding observed yield variability of the same components grown in 50:50 mixtures in a replacement design. Stability indices were calculated as ratios between the expected and observed variabilities, with values > 1 indicating greater stability of the intercrops. Mean grain yields tended to be higher in intercrops than sole crops. However, in contrast to our hypothesis, the observed (intercrop) yield stability was similar or lower than the expected (sole crop) stability in most locations except one. Furthermore, yield stability significantly increased with increasing mean yields when assessed across differentially productive locations. The results are relevant for the designing of intercropping systems as a means to increase yield stability and the resilience of cropping systems.

Effective and sustainable weed management in agricultural fields is a prerequisite for increasing crop yield without negatively impacting the environment. The aim of this study was to explore how varying nitrogen (N) availability in cropping arrangements of pea (Pisum sativum) and barley (Hordeum vulgare) grown as sole crops and intercrops at different fertilization levels and considering different N sources (soil mineralization, N fixation, N fertilizer) affects the response of weed species with differential N responsiveness. Crop and weed biomass were sampled at flowering and maturity. The total N content and ¹⁵N isotope signatures were analyzed to differentiate between N sources and to estimate the amount of N available to weeds. The highly N-responsive weed (Chenopodium album) accumulated more N and biomass than the weed with reduced N responsiveness (Galeopsis spp.). Fertilizer supply favored Chenopodium album, but not the crops. Altered soil N availability caused a shift in the dominance of the nitrophilic weed species towards the highly N-responsive species. This shift in dominance could affect the long-term weed community composition and thus have implications for sustainable weed management.

Cereal–legume mixtures are often associated with higher yields than the components grown as sole crops, but the underlying mechanisms are unclear. The study aims to evaluate how different cultivars in a two-species wheat–faba bean mixture influence above- and below-ground nitrogen (N) accumulation in the plant biomass, whether crop mixing affected the accumulation of other nutrients relative to the accumulation of N and phosphorus (P), and how the nutrient accumulation pattern in sole crops and mixtures is influenced by weed competition. Using a growth container experiment, we investigate nutrient accumulation patterns on specific wheat and faba bean cultivars grown as sole crops and mixtures, and with and without weed competition. We found that cereals in the mixture accumulated more N than in the sole crops, and the cultivar used influenced biomass accumulation in the legumes. Competition from weeds reduced the amount of plant N pools accumulated in the crop plant biomass. Based on stoichiometric scaling exponents, the plant neighbor affected the accumulation of other nutrients relative to the accumulation of N and P. These results are relevant for species and cultivar selection, all of which are important prerequisites for maximizing mixture performance.