The Effect of Inorganic Nitrogen Fertilizers on the Quality of Forage Composed of Various Species of Legumes in the Northern Part of a Temperate Climate Zone.

This study focuses on the effect of inorganic nitrogen fertilizers on the quality of perennial grasses. Both grasses and legumes are important in swards, and each type of grass has different biological and ecological properties. Legumes in multi-species swards, especially in their early ages, benefit other Poaceae grasses by improving their growth. When evaluating individual cuts over a three-year period, it was determined that the quality indicators of the forage were significantly influenced by the year of use, N fertilizer application, and the different species compositions of the swards. In many cases, N fertilizers significantly reduced the CP content while tending to increase MADF and NDF. Monoculture grass swards had the highest WSC content; in most cases, N fertilizers increased the WSC content in the forage. DMD was the lowest in the first year of use, specifically in the first cut. Our three-year experiment, which investigated twelve swards with different species compositions, demonstrated that legume grasses improved the quality indicators of forage and contributed to maintaining a more stable overall forage yield over the years. As the climate continues to become warmer, there is a growing need to study a wide range of plant species and different varieties suitable for local growth conditions.

An experimental dataset on yields of pulses across Europe.

Future European agriculture should achieve high productivity while limiting its impact on the environment. Legume-supported crop rotations could contribute to these goals, as they request less nitrogen (N) fertilizer inputs, show high resource use efficiency and support biodiversity. However, legumes grown for their grain (pulses) are not widely cultivated in Europe. To further expand their cultivation, it remains crucial to better understand how different cropping and environmental features affect pulses production in Europe. To address this gap, we collected the grain yields of the most cultivated legumes across European countries, from both published scientific papers and unpublished experiments of the European projects LegValue and Legato. Data were integrated into an open-source, easily updatable dataset, including 5229 yield observations for five major pulses: chickpea (Cicer arietinum L.), faba bean (Vicia faba L.), field pea (Pisum sativum L.), lentil (Lens culinaris Medik.), and soybean (Glycine max (L.) Merr.). These data were collected in 177 field experiments across 21 countries, from 37° N (southern Italy) to 63° N (Finland) of latitude, and from ca. 8° W (western Spain) to 47° E (Turkey), between 1980 and 2020. Our dataset can be used to quantify the effects of the soil, climate, and agronomic factors affecting pulses yields in Europe and could contribute to identifying the most suitable cropping areas in Europe to grow pulses.

Effects of Pea (Pisum sativum L.) Cultivars for Mixed Cropping with Oats (Avena sativa L.) on Yield and Competition Indices in an Organic Production System.

The benefits of cereal-legume mixed cropping is a sustainable agricultural practice. However, knowledge of the genotypic differences of semi-leafless pea varieties is not enough to help them compete with cereals. In this study, the effects of Lithuania's newest Pisum sativum cultivars ('Egle DS' and 'Lina DS') and, for comparison, a control cultivar ('Jura DS') established with Avena sativa in mixed cropping system were investigated. Three years of field trials (2018, 2019 and 2020) with four experiments involved three different mixtures of each field pea cultivar with oat. The aboveground biomass of mixed cropped new field pea cultivars was found to be significantly higher: biomass of cultivars 'Egle DS' increased by 17.0% and 'Lina DS' by 7.2% on average compared with the control cultivar 'Jura DS'. For the mixed cropping system, statistically greater total aboveground biomass was observed with plant ratios of 50% pea + 50% oat and 60% pea + 40% oat compared to peas monocultures. Mixed cropped oat was the dominant species in all tested mixture compositions; however, the highest total grain yield of mixed crops was obtained when new pea 'Lina DS' and 'Egle DS' cultivars were included in the mixtures compared with the control cultivar. The new pea cultivar 'Egle DS' had a greater effect on protein content compared to other tested pea cultivars. In the new pea cultivars 'Lina DS' and 'Egle DS', the higher photosynthetic capacity and aboveground biomass of mixed cropped pea with oat showed mixture effects in the mixed cropped system and could increase total yield compared with pea monoculture. Generally, the new pea cultivars displayed a greater Land Equivalent Ratio (LER) value, resulting in the greatest yield among the mixtures on average for all three years and all four experiments. Future research could optimize the effects of pea cultivar mixtures with cereals to further improve the yield of organic mixed cropping systems.

Soil Nitrate Nitrogen Content and Grain Yields of Organically Grown Cereals as Affected by a Strip Tillage and Forage Legume Intercropping.

Reducing tillage intensity and increasing crop diversity by including perennial legumes is an agrotechnical practice that strongly affects the soil environment. Strip tillage may be beneficial in the forage legume-cereals intercropping system due to more efficient utilization of biological nitrogen. Field experiments were conducted on a clay loam Cambisol to determine the effect of forage legume-winter wheat strip tillage intercropping on soil nitrate nitrogen (N-NO3) content and cereal productivity in various sequences of rotation in organic production systems. Forage legumes (Medicago lupulina L., Trifolium repens L., T. alexandrinum L.) grown in pure and forage legume-winter wheat (Triticum aestivum L.) strip tillage intercrops were studied. Conventional deep inversion tillage was compared to strip tillage. Nitrogen supply to winter wheat was assessed by the change in soil nitrate nitrogen content (N-NO3) and total N accumulation in yield (grain and straw). Conventional tillage was found to significantly increase N-NO3 content while cultivating winter wheat after forage legumes in late autumn (0-30 cm layer), after growth resumption in spring (30-60 cm), and in autumn after harvesting (30-60 cm). Soil N-NO3 content did not differ significantly between winter wheat strip sown in perennial legumes or oat stubble. Winter wheat grain yields increased with increasing N-NO3 content in soil. The grain yield was not significantly different when comparing winter wheat-forage legume strip intercropping (without mulching) to strip sowing in oat stubble. In forage legume-winter wheat strip intercropping, N release from legumes was weak and did not meet wheat nitrogen requirements.

Weed suppression greatly increased by plant diversity in intensively managed grasslands: A continental-scale experiment.

Grassland diversity can support sustainable intensification of grassland production through increased yields, reduced inputs and limited weed invasion. We report the effects of diversity on weed suppression from 3 years of a 31-site continental-scale field experiment.At each site, 15 grassland communities comprising four monocultures and 11 four-species mixtures based on a wide range of species' proportions were sown at two densities and managed by cutting. Forage species were selected according to two crossed functional traits, "method of nitrogen acquisition" and "pattern of temporal development".Across sites, years and sown densities, annual weed biomass in mixtures and monocultures was 0.5 and 2.0 t  DM ha-1 (7% and 33% of total biomass respectively). Over 95% of mixtures had weed biomass lower than the average of monocultures, and in two-thirds of cases, lower than in the most suppressive monoculture (transgressive suppression). Suppression was significantly transgressive for 58% of site-years. Transgressive suppression by mixtures was maintained across years, independent of site productivity.Based on models, average weed biomass in mixture over the whole experiment was 52% less (95% confidence interval: 30%-75%) than in the most suppressive monoculture. Transgressive suppression of weed biomass was significant at each year across all mixtures and for each mixture.Weed biomass was consistently low across all mixtures and years and was in some cases significantly but not largely different from that in the equiproportional mixture. The average variability (standard deviation) of annual weed biomass within a site was much lower for mixtures (0.42) than for monocultures (1.77). Synthesis and applications. Weed invasion can be diminished through a combination of forage species selected for complementarity and persistence traits in systems designed to reduce reliance on fertiliser nitrogen. In this study, effects of diversity on weed suppression were consistently strong across mixtures varying widely in species' proportions and over time. The level of weed biomass did not vary greatly across mixtures varying widely in proportions of sown species. These diversity benefits in intensively managed grasslands are relevant for the sustainable intensification of agriculture and, importantly, are achievable through practical farm-scale actions.