Search

Increasing evidence on environmental and economic benefits has raised farmers' interest in adopting alternative, less intensive soil management practices. To evaluate the influence of weed-competitive ability in response to a different tillage regime, a field study was conducted in maize under humid Central European climatic conditions in Slovenia. This study was established as a split-plot arrangement with three tillage practices (TPs) as the main plot: conventional (CN), conservation (CS), and no tillage (NT); this was combined with glyphosate application and the weed removal timing as the subplot. The weed removal timings were at the V3, V6, V9, V15, and R1 maize stages, with weed-free and weed season-long monitoring. The beginning and the end of the critical period of weed control (CPWC), based on a 5% maize yield loss rate, were determined by fitting the four-parameter log-logistic equations to the relative maize dry grain yield. The weed dry biomass from maize germination until the R1 growth stage in the NT TP was consistently lower than that in the CN and CS TP. Moreover, the NT TP resulted in a shorter CPWC (39 days after emergence (DAE)) compared to the CN (57 DAE) and CS (58 DAE). The results of CTWR (critical timing of weed removal) showed that less intensive tillage operations in the CS resulted in an earlier need for weed control (V2 and 23 DAE) compared to the CN (V3 and 39 DAE) and NT (V3 and 40 DAE). Our study suggests that the intensive tillage operations performed in the CN TP and the pre-sowing use of non-selective burndown herbicide in the NT delay the CTWR by more than 2 weeks, thus reducing the need for early post-emergence herbicide application in maize. [ABSTRACT FROM AUTHOR]

Soybean (Glycine max (L.) Merr.) is the most important protein crop globally, with its cultivation area in Europe on the increase. To investigate how alternative tillage systems affect soybean growth, yield performance, and nitrogen fixation capacity in the early conversion period from conventional tillage to conservation and no-tillage practices, a field study was conducted in 2020 under the humid central European climatic conditions of Slovenia. A complete randomized block design with four repetitions was used for the three different tillage systems (conventional, conservation, and no-tillage). The results show that the majority of the studied soybean growth parameters (e.g., plant density, nodes per plant, and shoot and root dry matter) and the yield components (e.g., pods per plant, and 100-seed mass) were greatest for the reference conventional tillage system. The conventional system also showed significantly greater dry nodule mass (p < 0.01) and proportion of large-sized nodules (>4 mm) on both the tap root (p < 0.05) and the lateral roots (p < 0.001). A positive linear correlation between nitrogen content and nodule production in the roots also suggested increased nitrogen fixation for the conventional system. The less intensive conservation and no-tillage systems resulted in significantly greater soil compaction, which negatively affected early plant establishment and resulted in significantly decreased plant densities. Despite the large differences in plant stands and individual plant performances, no significant differences were seen for dry seed yields between these tillage systems. Dry seed yields for the conventional and conservation systems were 4.54 and 4.48 t ha−1, respectively, with only minor (non-significant) yield reduction for the no-tillage system, at 4.0 t ha−1. These data show that soybean cultivation in the early transition period to less intensive tillage systems have no major yield losses under these less suitable agro-climatic conditions if correct crop and weed management measures are implemented. [ABSTRACT FROM AUTHOR]

Dry matter partitioning and allocation is a major determinant of plant growth and its competitiveness. Common ragweed ( Ambrosia artemisiifolia) is a troublesome agronomic weed species and it is also a major health concern in Europe and many other countries because of its rapid spreading and production of allergenic pollen. A field experiment was conducted in 2009 to determine the effect of nitrogen fertilizer levels (0, 100, and 200 kg ha−1) and plant density levels (1.3, 6.6, and 13.2 plants per m2) on the leaf, stem dry matter partitioning, and dry matter allocation of ragweed. With an increasing density, the stem partitioning coefficient increased, whereas the leaf partitioning coefficient decreased. The addition of nitrogen had a limited effect on the leaf and stem dry matter partitioning. The root dry matter production decreased with an increasing density and was not influenced by the addition of nitrogen. Under intraspecific competition, ragweed exhibited a stronger above-ground competition intensity than below the ground, which resulted in a greater root : shoot ratio, compared to the low-density stands. The level of nitrogen influenced the vertical leaf, stem, and total dry matter distribution, with a greater allocation to the top stratum of the plants, thus increasing their competition for light. The biomass allocation of ragweed to the roots in response to the nitrogen supply exhibited a low plasticity, compared to the shoots, which displayed a high plasticity. The results of this study suggested that, under intraspecific conditions and with an increasing nitrogen supply, ragweed would be more competitive in above-ground resource acquisition. [ABSTRACT FROM AUTHOR]

Hedge bindweed (Calystegia sepium L.) is a widespread troublesome perennial weed species that has strong rhizome regenerative capacity. Four pot trials with randomised, complete block designs were conducted in 2015 to evaluate long-term control of hedge bindweed using individual, tank mixture, and sequential applications of selected herbicides. Two different formulations of N-(phosphonomethyl) glycine (glyphosate; isopropylamine, trimesium salts) were applied at 2000 g active ingredient (a.i.) ha−1. Additionally, two synthetic auxins were applied as 3,6-dichloro-2-methoxybenzoic acid (dicamba) at 500 g a.i. ha−1 and the dimethylamine salt of (2,4 dichlorophenoxy)acetic acid (2,4-D) at 1000 g a.i. ha−1. Tank mixtures and sequential applications (12/24 h separation) of these different herbicides were also included. Long-term control of hedge bindweed, Calystegia sepium L., growth was evaluated 8 months after treatments, as comparisons of shoot and rhizome growth (biomass) between untreated and treated plants. There were no differences between the two formulations of glyphosate alone, with shoot and rhizome biomass reductions of 83% and 42%, respectively. Dicamba alone inhibited shoot and rhizome biomass by 86% and 67%, respectively. By itself, 2,4-D provided the greatest reductions in shoot and rhizome biomasses, 93% and 79%, respectively. Antagonism was seen in the tank mixtures of glyphosate and dicamba or 2,4-D. Tank mixtures were generally comparable to treatments of glyphosate alone, and were less effective compared to dicamba or 2,4-D alone. The greatest reduction of bindweed rhizome biomass was for sequential glyphosate trimesium salt followed by 2,4-D 12 h later, thus showing significantly greater efficacy over glyphosate isopropylamine salt (94% vs. 84%; p ≤ 0.05). These data for reductions of the growth of the rhizome biomass show that the sequential application of glyphosate followed by 2,4-D significantly improves long-term control of hedge bindweed. [ABSTRACT FROM AUTHOR]

In recent decades, adoption of less intensive soil tillage practices has increased due to numerous environmental and economic benefits. Our investigation was performed during 2020–2022 and examined germinable and persistent weed seed bank response in the early conversion period from conventional (CN) to conservation (CS) and no-tillage (NT) system under the humid, temperate climate of central Europe. The germinable seed bank determined in the spring cropping period was up to four times greater compared to the autumn cropping period. By using NT, consistently lower germinable weed seed banks were seen compared to CN or CS with observed reductions of weed seed density 45–75%. Final abundance of persistent weed seed bank (117,000 seeds m−2) was considerably greater than average size of germinable weed seed bank across years (27,000 seeds m−2). The vertical distribution of germinable weed seed bank in the soil did not differ between the tillage treatments, while using CS and CN more persistent weed seeds were accumulated in the intermediate (5–10 cm) or the bottom (10–20 cm) soil layer. CS and NT facilitated greater weed species diversity and evenness in both germinable and the persistent weed seed bank. Our results showed that introduction of different tillage systems had an almost immediate response in the size of germinable weed seed bank in the soil. Thus, when converting new fields to alternative tillage systems with high weed pressure, weed seed bank studies are advocated to select systems that reduce germinable seed in the seedbank. This method will enable coherent integration of non-chemical weed management strategies and support existing IWM methods in transition to sustainable agroecological based weed management strategies. • Persistent weed seed bank greatly exceeded germinable weed seed bank stock. • No-till resulted in rapid and consistent reduction of germinated weed seeds at all soil depths. • Alternative tillage practices did not alter vertical weed seed distribution pattern in either of both weed seed banks • Weed diversity and evenness were facilitated by spring cropping and less intensive tillage. [ABSTRACT FROM AUTHOR]

Rumex obtusifolius (broad‐leaved dock) is a problematic weed that reduces yield and nutritional value of forage in grasslands of temperate regions worldwide. We conducted an on‐farm study to identify management practices and environmental factors that influence the risk of the occurrence of R. obtusifolius in high densities in permanent, productive grasslands used for forage production. Following a common protocol, a paired case–control design was implemented in Switzerland (CH), Slovenia (SI), and United Kingdom (UK) to compare parcels with high densities of R. obtusifolius (cases, ≥1 plant m−2) with nearby parcels free of or with very low densities of the species (controls, ≤4 plants 100 m−2). A total of 40, 20, and 18 pairs were recorded in CH, SI, and UK respectively. Parameters measured included data about management practices and history, vegetation cover and composition, and soil nutrients and texture. Across countries, increased vegetation cover reduced the relative risk of R. obtusifolius occurrence. By contrast, increased soil phosphorus and potassium and high soil bulk density raised the relative risk. These effects were consistent across countries, as no interactions between country and any of the factors were observed. The two indicator species for case parcels, Plantago major and Poa annua, were typical species of disturbed areas and fertile soils, while indicators for control parcels were characteristic of grasslands under medium to high management intensity (e.g., Festuca rubra, Cynosorus cristatus, Anthoxantum odoratum). We conclude that the risk for grassland infestation with R. obtusifolius can be significantly affected by management practices. Prevention measures should target phosphorus and potassium fertilisation to the forage plants' requirements, minimise soil compaction, and maintain dense swards. [ABSTRACT FROM AUTHOR]

Rumex obtusifolius is a problematic weed in temperate grasslands worldwide as it decreases yield and nutritional value of forage. Because the species can recruit from the seed bank, we determined the effect of management and soil properties on the soil seed bank of R. obtusifolius in intensively managed, permanent grasslands in Switzerland (CH), Slovenia (SI), and United Kingdom (UK). Following a paired case-control design, soil cores were taken from the topsoil of grassland with a high density of R. obtusifolius plants (cases) and from nearby parcels with very low R. obtusifolius density (controls). Data on grassland management, soil nutrients, pH, soil texture, and density of R. obtusifolius plants were also collected. Seeds in the soil were germinated under optimal conditions in a glasshouse. The number of germinated seeds of R. obtusifolius in case parcels was 866 ±152 m-2 (CH, mean ±SE), 628 ±183 m-2 (SI), and 752 ±183 m-2 (UK), with no significant difference among countries. Densities in individual case parcels ranged from 0 up to approximately 3000 seeds m-2 (each country). Control parcels had significantly fewer seeds, with a mean of 51 ±18, 75 ±52, and 98 ±52 seeds m-2 in CH, SI, and UK, respectively, and a range between 0 and up to 1000 seeds m-2. Across countries, variables explaining variation in the soil seed bank of R. obtusifolius in case parcels were soil pH (negative relation), silt content (negative), land-use intensity (negative), and aboveground R. obtusifolius plant density (positive). Because a large soil seed bank can sustain grassland infestation with R. obtusifolius, management strategies to control the species should target the reduction in the density of mature plants, prevention of the species' seed production and dispersal, as well as the regulation of the soil pH to a range optimal for forage production. [ABSTRACT FROM AUTHOR]

During the period 2004–2015, the upper soil layer (0–20 cm) was sampled in eight agricultural production areas in Slovenia. Overall, 53, 249, 169, 139, and 413 samples were respectively taken from vegetable fields, arable cropland, hop fields, orchards, and vineyards. Copper was measured in the aqua-regia extracts of these samples using flame atomic absorption spectrometry. The minimum, maximum, average, and median concentrations were calculated for five land uses and for all eight production areas in Slovenia. Sample portions below and/or above the limit, warning, and critical concentrations of 60, 100, and 300 mg/kg, respectively, were calculated as well. The results were compared for different land uses and production areas and showed that the copper concentrations in the vegetable, arable crop, and hop fields and orchards did not exceed the critical concentration. In addition, the copper concentrations in the vineyards exceeded the critical concentration but the maximum copper concentration (508 mg/kg) was still lower than the concentrations reported from other vine-growing Mediterranean countries. Also, the copper concentrations in hop fields exhibited an increasing trend in the Celje (and Maribor) area(s). [ABSTRACT FROM AUTHOR]