Low yields remain a primary obstacle to the expansion of organic farming in Europe. While legume-based mixed cropping enhances land-use efficiency, three-crop mixtures remain understudied compared to binary systems. We evaluated the vegetative and generative growth of pea (Lathyrus oleraceus Lam.), oats (Avena sativa L.), and camelina (Camelina sativa (L.) Crantz.) in sole stands versus three-crop mixtures in southern Finland. Experiments were conducted over two years using varying relative seeding densities (including 50:20:30, 50:50:50, and 33:33:33). Biomass dynamics and seed quality were analyzed using analysis of variance (ANOVA), while interspecific interactions were quantified using the relative interaction index (RII) and land equivalent ratio (LER). In 2022, mixtures increased oat seed protein by 11% relative to sole crops, achieving a biomass LER of 1.17. In 2023, oats exhibited strong competitive dominance (RII > 0.3), which concurrently reduced camelina quality. Notably, the 33:33:33 mixture consistently achieved a biomass LER > 1.2 and marked improvements in pea growth rates. Across all mixtures, the seed yield LER reached 1.04. These results suggest that three-crop mixtures can enhance productivity in Nordic organic agriculture with minimal quality trade-offs. Practically, we recommend the equal seeding density (33:33:33) as the optimal configuration for maximizing resource use efficiency, though further optimization of species combinations is encouraged.

Weed competition, persistent seed banks, and management costs can limit crop productivity in organic farming. A two-year field experiment was conducted in southern Finland to evaluate the effects of pea (Lathyrus oleraceus Lam.), oats (Avena sativa L.), and camelina (Camelina sativa (L.) Crantz.), grown as pure stands and as three-crop mixtures at varying seeding densities, on weed diversity and suppression. The seeding densities (%) were 50:20:30 and 33:33:33 of the pure stand density of pea, oats, and camelina in 2022 and 50:50:50 and 33:33:33 of the pure stand density in 2023. Weed diversity was assessed at five sampling times, species were identified and analyzed for biomass, richness, Shannon-Wiener index (H), evenness, and dominance. Weed diversity and suppression varied with crop composition, growth stage, and seasonal conditions. In 2022, the 33% mix had the highest H (2.22) and evenness (0.77), enhancing weed suppression while controlling dominance. In 2023, pure oats had the highest H (1.65) and evenness (0.87), and pure peas had the lowest H (1.41) and evenness (0.67). Although pure oat stands provided the strongest weed suppression, crop mixtures enhanced species diversity and evenness, suggesting potential for more balanced weed management in organic systems, with short-term results indicating potential benefits for weed control.

Efficient water management and soil salinity are major constraints on cotton (Gossypium hirsutum L.) production in southern Xinjiang. This study evaluated the impacts of three irrigation leaching regimes (W1: 75 mm + 80% ETc, W2: 150 mm + 80% crop evapotranspiration (ETc), W3: 240 mm + 80% ETc) applied at different stages (seeding, budding, flowering), compared with a control of 450 mm spring irrigation (CK), on cotton growth, yield, quality, and water-use efficiency (WUE). The optimal leaching amount was found to range between 155–240 mm, with the W2C and W3C treatments performing the best. To integrate eight fiber indices, five growth parameters, yield, and WUE, comprehensive assessment models were established Four integrated evaluation models (Broda, Copeland, fuzzy Borda, and overall difference-based evaluation) exhibited strong consistency (Spearman coefficient > 0.98). Results from the fuzzy Borda model indicated optimal performance under treatments W2C and W3C. Additionally, a regression model suggested that cotton production was optimized when cumulative irrigation and rainfall reached approximately 326.3 mm, with leaching amounts applied during seeding, budding, and flowering stages. These findings provide practical guidelines for effective leaching practices to reduce soil salinity and to sustainably enhance cotton productivity in southern Xinjiang.