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.

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.

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 (CPo), 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.

The sustainability of an organic crop rotation frequently depends on the residual effects of legume pre-crops. However, the contribution of legumes varies considerably depending on their species as well as local soil and climatic conditions. This research aims to compare the pre-crop effects of traditional grain and forage legumes with those of soybean (Glycine max (L.) Merr.), which is not widespread in Europe latitude 55° due to climatic constrains, on the productivity of subsequent cereals. A three-year (2016-2018) crop rotation was investigated using four pre-crops: spring barley, spring barley intercropped with red clover, pea and soybean. The effect of pre-crops on grain yield and quality and chemical composition of subsequently grown spring wheat was explored. Nitrogen (N) content in grain and straw, mineral nitrogen (N min) content in the soil were measured, the carbon to nitrogen (C:N) ratio and net N balance were calculated. The rotation was repeated twice and the results showed that pea and soybean did not produce sufficient biomass and amount of fixed N to maintain a stable positive residual effect in both rotation replications. Under favourable conditions, pea derived 66.1 kg ha-1 N and soybean-64.7 kg ha-1 N from the atmosphere, while red clover intercropped with spring barley produced 65.4-82.7 kg ha-1 N yearly. Most of the total N (N tot) accumulated by pea and soybean plants, 69% and 80%, respectively, was removed with grain yield, while comparable percentages of N (59-68%) were left by the residues of red clover and spring barley mixture. As a result, the greatest effect on subsequently grown spring wheat was exerted by the mixture of spring barley and red clover (yield increase 354-1414 kg ha-1). Comparing grain legumes, only efficiently nodulated soybean produced a positive +20.6 kg ha-1 net N balance and increased the yield of spring wheat by 920 kg ha-1. Pea resulted in the negative net N balance and increased the yield of spring wheat by 534 kg ha-1. Mineral nitrogen in the soil increased under all legume pre-crops only in the second year of the crop rotation.