No abstract

Summary Several Fusarium species cause harmful cereal diseases, such as fusarium head blight and crown rot, which, during pathogenesis, may result in significant grain yield and quality losses. Several species of agricultural weed are believed to be alternative and reservoir hosts for Fusarium spp.; however, studies have not comprehensively evaluated those weed species in cropping systems that may harbour these fungi. The objective of this study was to determine weed species in cereal‐based crop rotations that are asymptomatically colonised by Fusarium spp. We sampled all species of weed present in fields that were managed under six different crop sequences in 2015 and 2016. The study yielded 2326 single‐spore isolates of Fusarium spp. derived from various organs of asymptomatic weeds. Isolates were identified morphologically and then confirmed using PCR with species‐specific primers and/or sequencing of tef1α gene fragments. Isolates of nine Fusarium spp. were obtained from 689 of the 744 individuals collected that represented 56 weed species. Each weed species harboured at least one species of Fusarium, and >80% were colonised by 3–9 Fusarium spp. In total, we identified 27 dicotyledonous weed species that were previously undocumented as Fusarium hosts and 251 new weed × Fusarium species combinations were revealed. Consequently, there is a greater risk of negative Fusarium impacts on cereal crops than was previously thought. We suggest effective weed management and inversion soil tillage may help mitigate these impacts.

Carbon dioxide (CO 2 ) efflux from 0-5 cm topsoil layer in conventional tillage plots, in grassland and forest Retisol (in West Lithuania in a hilly terrain) and Cambisol (in Central Lithuania in a plane terrain) was investigated using a closed chamber method. The soil CO 2 efflux was measured six times per growing season from April to August in 2018. Soil temperature and the volumetric water content were recorded at 5 cm depth at the same time as soil CO 2 efflux measurements. Small soil monoliths were collected for the measurements of plant root parameters within 0-10 cm layer and were investigated later in the laboratory. In Cambisol, the efflux values ranged from 0.20 to 2.67 μmol CO 2 m -2 s -1 under conventional tillage, from 1.10 to 3.41 μmol CO 2 m -2 s -1 in grassland and from 0.89 to 2.28 μmol CO 2 m -2 s -1 in forestland. In Retisol, the efflux values varied from 0.81 to 3.54 μmol CO 2 m -2 s -1 under conventional tillage, from 1.23 to 2.69 μmol CO 2 m -2 s -1 in grassland and from 0.88 to 2.06 μmol CO 2 m -2 s -1 in forestland. The soil temperature varied from 11.5°C to 33.6°C during the experimental period and averaged 22.8°C and 21.1°C at 5 cm depth in Cambisol and Retisol, respectively. The volumetric water content at 5 cm depth averaged 18.7% and 23.9% in Cambisol and Retisol, respectively. The volumetric water content in Cambisol was markedly lower than in Retisol during the whole experimental period. The maximum root volume within 0-10 cm depth was determined in grassland Retisol. Root volume under conventional tillage in Cambisol was 6.2-fold lower, in Retisol -5.1-fold lower, in forest Retisol -1.9-fold lower, in forest Cambisol -1.4-fold lower and in grassland Cambisol -1.1-fold lower compared to grassland Retisol. Average CO 2 efflux from Retisol was 12% lower than that from Cambisol. Soil CO 2 emission decreased in the following order: Cambisol -grassland > forestland > conventional tillage plots and Retisol -grassland > conventional tillage plots > forestland. Volumetric water content was found to increase soil CO 2 efflux; however, at the content higher than 20%, efflux decreased. A soil temperature of up to 25°C increased soil CO 2 emission. However, with a further increase in soil temperature, soil respiration decreased in both soil types investigated. The decrease in root volume and root length density depended on the land use: grassland > forestland > conventional tillage plots.

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.

Little is known about the effects of modern soil management practices, especially no-tillage, on soil physical state, soil pore size distribution and soil water capacity after a long-time of successive application on different soil types. The investigations were performed in 2014 at the Institute of Agriculture, Lithuanian Research Centre for Agriculture and Forestry in Central Lithuania's lowland on a sandy loam-textured Endocalcari-Epihypogleyic Cambisol (CMg-p-w-can) and at the Experimental Station of Aleksandras Stulginskis University on a silt loamtextured Endohypogleyic-Eutric Planosol (PLe-gln-w). The goals of this paper were a) to compare soil water capacity, soil pore-size distribution and CO 2 e-flux in Cambisol and Planosol, b) to evaluate the effect of long-term no-tillage application in combination with and without residue management on hydro-physical properties of soils with different genesis and c) to assess the suitability of such management practice for practical use. Regarding different soils genesis, the lower bulk density and higher total porosity were registered within 0-20 cm depth in Planosol than in Cambisol, while Cambisol was better aerated than Planosol due to a greater space of macropores. A risk of waterlogging condition may occur in Planosol due to a greater share of meso-and microporosity within 5-35 cm soil depth, compared to Cambisol. No-tillage application with crop residue returning was more suitable on Cambisol than on Planosol. This soil management system increased volumetric water content in the soil and CO 2 e-flux. No-tillage with residue removal on Cambisol conditioned soil CO 2 e-flux increase when volumetric soil water content ranged from 0.159 to 0.196 m 3 m -3 . When soil water content increased up to 0.220-0.250 m 3 m -3 , the e-flux peak was reached at which the further CO 2 e-flux sloped down. On Planosol, the soil CO 2 e-flux peak ranges were lower, i.e. approximately 0.170-0.200 m 3 m -3 . Long-term residue returning onto soil surface on Planosol acted as a physical obstruction inside mesopores in 5-10 cm and within macropores in 5-10 and 15-20 cm layers and, finally, causing clogging them. Increase of soil surface volumetric water content in Planosol caused a decrease in soil CO 2 e-flux.