Cereal-legume intercropping is important in many low-input agricultural systems. Interactions between combinations of different plant species vary widely. Field experiments were conducted to determine yield formation regularities and plant competition effects of oat (Avena sativa L.)–black medick (Medicago lupulina L.), oat–white clover (Trifolium repens L.), and oat–Egyptian clover (T. alexandrinum L.) under organic farming conditions. Oats and forage legumes were grown in mono- and intercrops. Aboveground dry matter (DM) measured at flowering, development of fruit and ripened grain, productivity indicators, oat grain yield and nutrient content were established. The results showed that oats dominated in the intercropping systems. Oat competitive performance (CP_o), which is characterized by forage legumes aboveground mass reduction compared to monocrops, were 91.4–98.9. As the oats ripened, its competitiveness tendency to declined. In oat–forage legume intercropping systems, the mass of weeds was significantly lower compared to the legume monocrops. Oats and forage legumes competed for P, but N and K accumulation in biomass was not significantly affected. We concluded that, in relay intercrop, under favourable conditions, the forage legumes easily adapted to the growth rhythm and intensity of oats and does not adverse effect on their grain yield.

Glyphosate is one of the most widely used herbicides, but is still in the spotlight due to its controversial impact on the environment and human health. The main purpose of this study was to explore the effects of different glyphosate usages on harvested grain/seed contamination. Two field experiments of different glyphosate usage were carried out in Central Lithuania during 2015–2021. The first experiment was a pre-harvest application, with two timings, the first according to the label (14–10 days), and the other applied 4–2 days before harvest (off-label), performed in winter wheat and spring barley in 2015 and 2016. The second experiment consisted of glyphosate applications at label rate (1.44 kg ha⁻¹) and double dose rate (2.88 kg ha⁻¹) at two application timings (pre-emergence of crop and at pre-harvest), conducted in spring wheat and spring oilseed rape in 2019–2021. The results suggest that pre-emergence application at both dose rates did not affect the harvested spring wheat grain or spring oilseed rape seeds—no residues were found. The use of glyphosate at pre-harvest, despite the dosage and application timing, led to glyphosate’s, as well as its metabolite, aminomethosphonic acid’s, occurrence in grain/seeds, but the amounts did not reach the maximum residue levels according to Regulation (EC) No. 293/2013. The grain storage test showed that glyphosate residues remain in grain/seeds at steady concentrations for longer than one year. A one year study of glyphosate distribution within main and secondary products showed that glyphosate residues were mainly concentrated in wheat bran and oilseed rape meal, while no residues found in cold-pressed oil and wheat white flour, when glyphosate used at pre-harvest at the label rate.

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.

Biogas slurry is widely used to fertilize crops. However, their impact on soil parameters and waxy winter wheat (Triticum aestivum L.) nutrition is poorly understood. The aim of this research was to determine the influence of liquid anaerobic digestate and pig slurry applied to waxy winter wheat on the dynamics of soil organic carbon (SOC) and total nitrogen (N_tot) in different forms on grain yield, and to compare them with the use of ammonium nitrate. The nitrogen rates (kg N·ha⁻¹) used for fertilization were N0, N60, N120, and N120+50. The study showed that the variation of nitrate nitrogen (N-NO₃) and water-extractable organic carbon (WEOC) in the soil during the growing season depended on N fertilizer rates, meteorological conditions of the year, and, to a lesser extent, on fertilizer forms. Meteorological conditions were responsible for the demand and supply of nutrients from the soil by the waxy winter wheat variety. This determined the wheat yield and the variation in the soil parameters studied. Over the 2 years, the soil C:N ratio decreased, especially at the medium and high N fertilizer rates. The lowest changes were observed in the unfertilized and fertilized plots at a rate of 60 kg N·ha⁻¹.

Diversifying crop rotations by incorporating legumes is recommended to enhance the resilience of agricultural systems against environmental stresses and optimize nitrogen utilization. Nonetheless, ploughing forage legumes or grass-legumes poses a significant risk of nitrate leaching. The study aimed to assess the impact of strip tillage intercropping management on soil mineral nitrogen, water-extractable organic carbon, mobile humic substances content, and winter wheat (Triticum aestivum L.) grain yield compared to forage legume and winter wheat monocropping with conventional tillage. In the intercropping systems, the following bicrops were used: black medick (Medicago lupulina L.) with winter wheat, white clover (Trifolium repens L.) with winter wheat, and Egyptian clover (Trifolium alexandrinum L.) with winter wheat. Research was conducted in two experiments. The results indicated that after implementing strip tillage and winter wheat intercropping, the soil mineral nitrogen content was similar to or lower than that observed in conventional tillage and winter wheat sowing after forage legumes. Winter wheat grain yield in intercrops decreased compared to the legumes monocultures that were ploughed before winter wheat sowing. The highest amount of water- extractable organic carbon was in intercropping growing white clover and winter wheat bicrops or in all fields (except Egyptian clover and winter wheat bicrops) after applying strip tillage. During the research period, the quantities of mobile humic substances and mobile humic acids exhibited similar changes. Their content increased substantially in fields with white clover and Egyptian clover, regardless of whether the legumes were ploughed or grown with winter wheat.

Crop rotation diversification using legumes has been advocated as one of the solutions to improve the resilience of the crop system to various environmental stresses and the use of nitrogen resources. However, when forage legumes or grass-legumes are ploughed, there is a high risk of nitrate leaching, especially in sandy soils. The aim of the study was to determine the effect strip tillage intercropping management on soil mineral nitrogen (SMN), water-extractable organic carbon (WEOC) content and winter wheat (WW, Triticum aestivum L.) grain yield compared to forage legume and WW monocropping with conventional tillage. In intercropping was used winter wheat - black medick (Medicago lupulina L.) WW+BM, winter wheat - white clover (Trifolium repens L.) WW+WC, and winter wheat - Egyptian clover (Trifolium alexandrinum L.) WW+EC. Research was repeated in two experiments. The results showed that after strip tillage and WW sowing less or similar SMN content cud be detected, as in conventional tillage and WW + forage legumes intercropping. WW grain yield in intercrops decreased, compared to the grasses monocultures that were ploughed before WW sowing. The highest amount of WEOC was in intercropping soil growing WW+WC or in all fields (except WW+EC) after applying strip tillage. During the research period, the amounts of mobile humic substances (HSs) and mobile humic acids (HAs) changed analogously. Their content increased substantially in fields with WC and EC, regardless of whether the grasses were ploughed or grown with WW.