Total Herbicide Research Articles

Another step on the transgene-facilitated herbicide treadmill.

Transgenic, dicamba-resistant soybean and cotton were developed to enable farmers to combat weeds that had evolved resistance to the herbicide glyphosate. The dramatic increases in dicamba use these crops facilitated have led to serious problems, including the evolution of dicamba-resistant weeds and widespread damage to susceptible crops and farming communities. Disturbingly, this pattern of dicamba use has unfolded while the total herbicide applied to soybean has nearly doubled since 2006. Without substantive changes to agricultural policy and decision making, the next 'silver-bullet' agrotechnology will likely be no more than another step on the transgene-facilitated herbicide treadmill. © 2024 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Occurrence, distribution and ecological risk assessment of herbicide residues in cropland soils from the Mollisols region of Northeast China

The first systematic and comprehensive investigation of herbicide residues was conducted by identifying their spatial distribution, influencing factors and ecological risk in cropland soils from the Mollisols region covering 109 million hm2 in Northeast China. Fifty-six herbicides were detected with total herbicide concentrations ranging from 1.01 to 1558.13 μg/kg (mean: 227.45). Atrazine, its degradates deethyl atrazine (DEA) and deisopropyl atrazine (DIA), trifluralin and butachlor were the most frequently detected herbicides, while DEA, clomazone, nicosulfuron, fomesafen, and mefenacet exhibited the highest concentrations. Despite being less frequently reported in Chinese soils, fomesafen, nicosulfuron, clomazone, and mefenacet were found widely present. Although most of the compounds posed a minimal or low ecological risk, atrazine, nicosulfuron and DEA exhibited medium to high potential risks. The key factors identified to regulate the fate of herbicides were soil chemical properties, amount of herbicides application, and the crop type. The soybean soils showed highest herbicide residues, while the soil mineral contents likely adsorbed more herbicides. This study provides a valuable large-scale dataset of herbicide residues across the entire Mollisols region of China along with fine-scale characterization of the ecological risks. Mitigation and management measures are needed to reduce the herbicide inputs and residues in the region.

Spatial distribution and ecological-health risks associated with herbicides in soils and crop kernels of the black soil region in China

Herbicides are vital inputs for food production; however, their associated risks and hazards are pressing concerns. In black soil, the cumulative toxic effects of compound herbicides and potential risks to humans are not yet fully understood. Thus, this study conducted a comprehensive investigation to assess herbicide residue characteristics and the associated ecological health risks in representative black soil regions where major food crops (maize, soybean, and rice) are cultivated. Findings revealed that the soil harbored a collective presence of 29 herbicides, exhibiting total concentrations ranging from 111.92 to 996.14 μg/kg dry weight (dw). This can be attributed to the extensive use of herbicides over the years and their long half-lives, which results in the accumulation of multiple herbicide residues in the soil. Similarly, the total herbicide levels in maize, soybean, and rice kernels were 1173–61,564, 1721–9342, and 3775–8094 ng/kg dw, respectively. Multiple herbicide residues at all monitored sites were attributed to continuous crop barriers in soybean fields and the adoption of soybean and maize crop rotations. Notably, herbicides pose ecological risks in the black soil region, exhibiting high-risk levels of 79 %, 24 %, and 14 % at the sites monitored for oxyfluorfen, clomazone, and butachlor, respectively. Carcinogenic atrazine exhibited low- and medium-risk levels in 34 % and 63 % of soil samples, respectively. These results can serve as a scientific basis for establishing herbicide residue thresholds in agricultural soils within black soil areas and for implementing effective control measures to prevent herbicide contamination in agricultural ecosystems.

Pollution characteristics, ecological and health risks of herbicides in a drinking water source and its inflowing rivers in North China

This study measured the pollution characteristics and ecological and health risks of 19 herbicides found in drinking water sources and their inflowing rivers. The targeted herbicides were prevalent in the study area, but most concentrations were well below 10 ng L−1. Acetochlor and atrazine were the dominant herbicides, although their levels were much lower than previously reported. Total herbicide residual levels were greater in April than in December and increased from upstream to downstream, resulting in the highest pollution levels found in the reservoirs, likely due to herbicides delivered from upstream and dense agricultural planting in the surrounding areas. Only atrazine and ametryn presented moderate ecological risks, while the summed risk quotients (ΣRQs) of each sample were >0.1, indicated that the total herbicide levels represented a moderate risk in all samples. For the human health risks, the risk quotients (RQ) of all target herbicides, the total RQs of each sample, and estimated life-stage RQs were far smaller than the 0.2 threshold, indicating the absence of human health risks when the water was consumed at any stage of life. However, early life stages exhibited 3–6 times higher RQ values than adulthood and should not be overlooked. And crucially, the synergistic or antagonistic effects of mixed herbicides are not well understood, and further research is needed to understand the impact of these herbicides on the ecosystem and human health, particularly possible affects in early life stages, such as infants and children.

Predicting springtime herbicide exposure across multiple scales in pacific coastal drainages (Oregon, USA)

Identification of non-point sources of watershed pollution such as pesticide runoff is challenging due to spatial and temporal variation in landscape patterns of land use and environmental conditions. Regional case study monitoring investigations can document region-specific conditions and processes to inform managers about pesticide movement through watersheds. Additionally, modeling field-collected data within these contexts can be used to predict pesticide presence in un-sampled areas. During a 45 day period in the spring of 2019, we sampled sixteen coastal watersheds in Oregon, USA for current-use water-borne herbicides commonly used in forestland vegetation management. At 80 % of sampling locations, at least one of four commonly used herbicides was detected in integrative passive water samplers, with hexazinone and atrazine most commonly detected. In this study, we use total accumulation of detected compounds to compare relative detections with upstream management and environmental watershed variables using multiple linear regression. An additive effects model was developed using slope, herbicide activity notified during the sampling window, and recent clearcut harvest notifications to predict variation in total herbicide accumulation (R2 = 0.8914). The model was then applied to predict concentrations in un-sampled watersheds throughout the Oregon’s coastal region at three watershed scales using Hydrologic Unit Codes (HUCs) 8, 10, and 12. Regional differences in predicted values were visualized using choropleth maps. Subwatersheds (HUC12) were grouped by subbasin (HUC8) and base mean predicted values were compared to further quantify regional differences. Models predicted that south coast sites have higher than average herbicide concentrations, which aligned with field-collected data findings.

Analysing Farmers’ Herbicide Use Pattern to Estimate the Magnitude and Field-Economic Value of Crop Diversification

We present an on-farm approach to measure the effect of crop diversification on farmers’ field economic values. Eleven years of data (2010–2020) on the chemical herbicide use, tillage practices and crop yields of 17 farms in north-eastern Germany were examined for winter wheat (WW) and winter oilseed rape (WOSR). We used a common conceptual framework to classify farmers’ crop sequences according to their susceptibility to weeds (‘riskiness’). Linear mixed models were used to analyse the relationship between crop sequence, tillage practice (inversion/non-inversion) and the response variables ‘total herbicide costs’, ‘crop yield’ and ‘economic income’. Our results indicate that farmers in the area surveyed commonly grow crop sequences with a high risk of weeds. The driving forces behind this classification are high ratios of winter cereals and WOSR in the sequences. The most interesting result of our analysis is that farmers’ total herbicide costs (THCfy) significantly decreased from a higher to a lower riskiness class. Diversified crop sequences decreased the THCfy for WW by up to 12 EUR ha−1 and for WOSR by 19–56 EUR ha−1. Considering the crop diversification effects, the combined influence of tillage and crop sequence seems to be important. Significant differences in crop yield between the riskiness classes were found in WW and WOSR solely in non-inversion tillage systems. Hence, the analysis of farmers’ ‘economic income’ revealed the great impact of crop diversification for non-inversion tillage systems. Indeed, we found that simplifying both crop sequence diversity and tillage intensity implies higher herbicide costs and, thereby, higher economic input. The best strategy for reducing herbicide costs in WW and WOSR cropping is to increase the use of summer crops or field grass as previous crops.

​​Identifying Some Morphological Features of Mutant Quinoa Plants (Chenopodium quinoa Willd.)

Background: This research was carried out to obtain seeds from M1 and M2 level mutant plants of Titicaca cultivar of quinoa and to make some distinctive morphological observations. Methods: Sodium azide was applied to the Titicaca variety of quinoa in 2018 and planted in a random order on plots in the field to obtain seeds at M1 level. When the plants reached the maturity of the seed harvest, they were removed from the soil and the number of growing days, plant height, stem thickness, number of branches, biological yield, seed yield and harvest index were measured and calculated at the M2 generation study. The seeds obtained from the M1 generation were planted in the field. In the period when the plants had 3 leaves, total herbicide with imazamox active ingredient was applied to the green parts of the plants. Afterwards, resistant plants were determined and M2 seeds were produced. Then, some measurements were made by growing M2 seeds in vases under greenhouse conditions. Results from mutant plants were compared with control plants. Result: According to the measurements made, M1 generation it was seen that the average number of branches was statistically less in mutant plants than in control plants. No statistically significant difference was found between the measurements obtained from control and mutant plants for other features. However, according to the measurements made in the M2 generation, the difference between the values of the control and mutant plants was found to be statistically significant.

Accumulation of commonly used agricultural herbicides in coral reef organisms from iSimangaliso Wetland Park, South Africa

Coral reefs are amongst the most biodiverse ecosystems on earth, but are significantly impacted by agricultural runoff. Despite herbicides being commonly detected in coastal waters, the possibility of herbicide accumulation in coral reef species has largely been overlooked. We investigate the accumulation of several herbicides in five species of coral reef invertebrates collected from ten sites along the Maputaland coast, South Africa. Multiple herbicide residues were detected in 95% of the samples, with total average concentrations across sites ranging between 25.2 ng g−1 to 51.3 ng g−1 dw. Acetochlor, alachlor and hexazinone were the predominant herbicides detected at all sites, with atrazine and simazine detected less frequently. Significant interactive effects were detected between sites nested in reef complex crossed with species, based on multiple and total herbicide concentrations. In general, multivariate herbicide concentrations varied significantly between species within and across most sites. Contrastingly, the concentrations of the different herbicides and that of total herbicide did not differ between conspecifics at most sites nested in their respective reef complexes. On average, highest total herbicide concentrations were measured in soft coral (Sarcophyton glaucum; 90.4 ± 60 ng g−1 and Sinularia gravis; 42.7 ± 25 ng g−1) and sponge (Theonela swinhoei; 39.0 ± 40 ng g−1) species, while significantly lower concentrations were detected in hard corals (Echinopora hirsutissima; 10.5 ± 5.9 ng g−1 and Acropora austera; 5.20 ± 4.5 ng g−1) at most sites. Agricultural runoff entering the ocean via the uMfolozi-St Lucia Estuary and Maputo Bay are likely sources of herbicide contamination to coral reefs in the region. There is an urgent need to assess the long-term effects of herbicide exposure on coral reef communities.

Effect of different types of soil tillage for sunflower on some soil physical characteristics. Part I: soil moisture

Abstract The investigation was carried out during 2014–2016 in the land of General Toshevo town in the South Dobrudzha region on slightly leached chernozem soil type. The effect of the types of soil tillage for sunflower given bellow was followed: ploughing at 24–26 cm, chisel-plough at 24–26 cm, disking with disk harrow at 10–12 cm and direct sowing (no-tillage) on the soil moisture content. Based on bulk density, wilting point and the determined soil moisture content the plant-available water was calculated. The additional soil tilths of the areas subjected to ploughing, chisel-ploughing and disking with disc harrow included double spring pre-sowing cultivation with harrowing. To destroy the emerging weeds in the variant with direct sowing, a total herbicide was applied. The soil moisture content was evaluated during three main stages of sunflower development: emergence, flowering and technical maturity. The investigated parameter was determined for each of the studied layers – 0–10, 10–20, 20–30, 30–40 and 40–60 cm. In years with normal amounts of rainfalls, no significant differences in the soil moisture under the different ways of soil tillage were observed. Conventional ploughing and tillage without turning of the soil layer contributed to accumulation of more moisture and to higher moisture storage down the soil profile under heavy and intensive rainfalls. Tillage without turning of the soil layer, minimal and no tillage maintained more and better soil moisture in years with limited precipitation and in periods of drought.

Application Intensity and Spatial Distribution of Three Major Herbicides from Agricultural and Nonagricultural Practices in the Central Plain of Thailand.

The herbicides glyphosate, paraquat, and 2,4-D play a significant role in Thailand. This paper is among the first study to describe the intensity of herbicide application and illustrate how the herbicides are extensively distributed over a large area through both agricultural and nonagricultural practices. Using a quick, economical, and simplified method of Material Flow Analysis together with spatial analysis, better data for the analysis of possible environmental herbicide contamination, human exposure, and related health risks for the general public and applicators can be developed. The findings from this study showed that in the study province, about 2.2 million kg of the active ingredients from the three targeted herbicides is applied annually. Pathway flow modeling with spatial analysis identified several local hotspots of concern based on the type of herbicide and crop/activity where it was used. Cassava planting was found to have the highest herbicide application activity, whereas rice cultivation was the major contributor of total herbicide mass, due to the wide area of cultivation in the province. The herbicide most likely to be applied at rates higher than recommended was 2,4-D, particularly on cassava and sugarcane farms.

Trichoderma harzianum IS005-12 promotes germination, seedling growth and seedborne fungi suppression in Italian ryegrass forage

Potential of Trichoderma harzianum IS005-12 (TH-IS005-12) to promote seed germination and seedling growth of Italian ryegrass (IRG) forage was evaluated in vitro. Non-desiccated seeds and those pre-harvestly desiccated with total herbicide were treated 25 days (freshly harvested) and 178 days after harvest (mature) with TH-IS005-12 spore suspensions at 0 (T0), 1.8 × 10<sup>7</sup> (T1) and 1.2 × 10<sup>9</sup> (T2) spore/mL. TH-IS005-12 promoted the early and final germination and seedling growth in all non-desiccated and desiccated, freshly harvested as well as mature IRG seeds. It was more effective in pre-harvestly desiccated freshly harvested seeds where T2 treatment increased final germination rate for 24%, root number per seedling 1.6-fold and seedling vigour 1.9-fold compared to the untreated control. Moreover, TH-IS005-12 showed an inhibitory activity against seedborne fungi Alternaria alternata and A. ventricosa suppressing their growth in vitro by 82% and 77%, respectively.

Species composition and density of weeds in a grain maize crop depending of soil tillage

Abstract. The study was carried out during 2014-2016 on slightly leached chernozem soil type. The species composition and density of weeds were studied in grain maize grown after previous crop wheat under the following main soil tillage types: ploughing at 24-26 cm, chisel plough at 24-26 cm and no-tillage (direct sowing). The additional tilths of the areas with ploughed and loosened soil included single disking in autumn and double pre-sowing harrowing in spring. A total herbicide was applied for control of the emerging weeds in the variant with direct sowing. The weed control was done according to the standard technology for growing of the crop in this region – treatment with herbicides at stage 3rd-5th leaf of the plants. Weed infestation was read in spring prior to the pre-sowing tillage, immediately before the vegetation treatment with herbicides, and after harvesting. The type of main soil tillage had a statistically significant effect on the species composition and the density of weeds in the grain maize crops grown after previous crop wheat. The use of ploughing, in parallel with the use of chemicals for weed control, decreased the weed infestation in the maize crops. The lower density of weeds under this main soil tillage type was related to changes in the composition and the relative percentage of the respective species in the total infestation. The use of tilths without turning the surface layer and no-tillage in the crop rotation, in spite of the application of herbicides, contributed to the increase of the amount of weeds. The reason for this was the higher variability of weed species typical for shallow tillage types.

Effect of different types of soil tillage for sunflower on some soil physical characteristics. Part II: bulk density and soil temperature

Abstract The investigation was carried out during 2014–2016 in the land of General Toshevo, the South Dobrudzha region of Bulgaria on slightly leached chernozem soil type. The effect of the types of soil tillage for sunflower given bellow was followed: ploughing at 24–26 cm, chisel-plough at 24–26 cm, disking with disk harrow at 10–20 cm and direct sowing (no-tillage) on the bulk density, the moisture content and the temperature of soil. The additional soil tilths of the areas subjected to ploughing, chisel-ploughing and disking with disc harrow included double spring pre-sowing cultivation with harrowing. To destroy the emerging weeds in the variant with direct sowing, a total herbicide was applied. The investigated physical parameters of soil were followed during three main stages of sunflower development: emergence, flowering and technical maturity. The bulk density of soil was determined by soil samples taken from the 0–10, 10–20 and 20–30 cm layers. The soil temperature was read at 800, 1200 and 1600 h to depth 2, 5, 10, 15, 20 and 25 cm with classical soil thermometer. For evaluation of the results dispersion and regression analyses were used. In the slightly leached chernozem soil type, the conventional ploughing leads to lower bulk density in the cultivated soil profile. Under minimal tillage, slight increase of bulk density of the layer underlying the cultivated one was observed over time. The bulk density under tillage without turning of the soil layer and no-tillage was changed and formed primarily under the influence of physical and climatic factors, and under minimal tillage – under the cultivated layer. Under all investigated types of soil tillage, bulk density increased down the soil profile. Replacing ploughing with tillage without turning of the soil layer, minimal and no-tillage lead to decrease of soil temperature. The most significant differences were observed in the 0–10 layer, which, on its part, conditioned accumulation and transfer of thermal energy along the soil profile. The soil temperature decreased with the reduction of the number and depth of the soil tillage operations. The temperature amplitudes between the surface layer and the underlying soil horizons in the areas with ploughing, chisel ploughing minimal and no-tillage were lower. The results concerning the values of the investigated physical properties of soil under different types of soil tillage were statistically significant at different levels of P.

Comparison of sesame and lentil susceptibility to soil residual effects of total®, apirus®, and atlantis

This experiment was conducted in order to study the sensitivity of sesame (Sesamum indicum) and lentil (Lens culinaris) crops to soil residue of three herbicides including total, apirus, and atlantis under greenhouse conditions. It was observed that the low level of atlantis residue reduced the sesame stem length (91.61% compared to control). Besides, the lowest sesame stem length (33.30% compared to control) was observed at high level of the herbicide residue. Total herbicide compared to the other two herbicides had a greater destructive impact (89.93%) on the sesame stem dry weight. The results indicated that the maximum and minimum damages on the lentil stem length were created by the total (46.78%) and atlantis (23.33%), respectively. Furthermore, the values of GR50 and HR50 for sesame were significantly lower than lentil against application of total, apirus, and atlantis. Generally, sesame showed higher sensitivity than lentil against application of total, apirus and atlantis.

Introduction of the Nicotiana protein kinase (NPK1) gene by combining Agrobacterium-mediated transformation and recurrent somatic embryogenesis to enhance salt tolerance in cauliflower

Cauliflower is exposed to various biotic and abiotic stresses, including increased salinity due to the intensive irrigation of crops. Mitogen-activated protein kinase (MAPK) cascades are universal signal transduction modules that play important roles in regulating innate immune responses in plants. Based on involvement of tobacco MAP kinase kinase kinase (NPK1) in stress response, the effect of the expression of NPK1 transgene to NaCl salt stress tolerance in cauliflower KFRM4 lines was studied. The Agrobacterium tumefaciens-mediated transformation protocol, using EHA101(pSHX004) vector harbouring the NPK1 and phosphinothricin N-acetyltransferase (bar) genes, the cyclic somatic embryogenesis regeneration pathway, the application of acetosyringone (AS) during co-cultivation and a delayed phosphinothricine (PPT) selection procedure provided sufficient transformation efficiency of 7.33% without escapes. PCR analysis indicated the integration of both NPK1 and bar transgenes in regenerated cauliflower lines. Transgenic cauliflower lines, exposed to NaCl stress in vitro, showed higher growth rates, greater ability to retain chlorophyll and carotenoids, and increased osmotic regulation capacity compared with non-transformed control plants. The tolerance level of transformed lines correlated with the level of NPK1 gene expression estimated by RT-qPCR, and the L2 line with the highest NPK1 expression displayed the greatest tolerance to NaCl stress. None of the obtained cauliflower transformed lines grown in greenhouses showed any morphological or yield differences compared with non-transformed plants. Furthermore, the expression of the bar gene facilitated the tolerance of transformed lines to the total herbicide PPT, applied at concentrations 2–3 times higher than those routinely used for weed control in the crop field. The results underlined that constitutively expressing NPK1 can significantly contribute to enhanced salt stress tolerance in cauliflower, suggesting that this could be a promising basis for the creation of new stress tolerance cruciferous vegetable lines.

Herbicide residues in sediments from Lake St Lucia (iSimangaliso World Heritage Site, South Africa) and its catchment areas: Occurrence and ecological risk assessment

The impact of agricultural pesticides on sensitive aquatic ecosystems is a matter of global concern. Although South Africa is the largest user of pesticides in sub-Saharan Africa, few studies have examined the toxicological threats posed by agricultural runoff, particularly to conservation areas of international importance. This study investigated the occurrence of 11 priority listed herbicides in sediments from Lake St Lucia, located on the east coast of South Africa. While characterised by exceptionally high levels of biodiversity, Lake St Lucia is affected by agricultural runoff primarily via inflow from two major rivers; the Mkhuze and Mfolozi. Sediment samples collected from Lake St Lucia and its two major fluvial inputs reveal widespread herbicide contamination of the aquatic environment. Residues were detected in the vast majority of samples analysed, with Mkhuze (27.3 ± 17 ng g−1) and Mfolozi (25.6 ± 20 ng g−1) sediments characterised by similar total herbicide levels, while lower concentrations were typically detected in Lake St Lucia (12.9 ± 12 ng g−1). Overall, the most prominent residues detected included acetochlor (3.77 ± 1.3 ng g−1), hexazinone (2.86 ± 1.4 ng g−1) and metolachlor (10.1 ± 8.7 ng g−1). Ecological assessment using Risk Quotients (RQs) showed that cumulative values for triazines and anilides/aniline herbicide classes presented low to medium risk for algae and aquatic invertebrate communities. Considering the biological importance of Lake St Lucia as a nursery for aquatic organisms, it is recommended that further research on the aquatic health of the system be undertaken. Additional monitoring and investigation into mitigation strategies is suggested, particularly as agricultural activities surrounding Lake St Lucia are likely to expand in the future.

Combining weed efficacy, economics and environmental considerations for improved herbicide management in the Great Barrier Reef catchment area

The current Australian sugarcane industry transition toward adoption of an ‘alternative’ herbicide strategy as part of improved environmental stewardship is increasingly complicated by recent farming system, regulatory and herbicidal product changes. This study quantified and compared the efficacy, economic costs and environmental risk profiles of a range of established, emerging, and recently registered pre-emergent herbicides across field trials in the Wet Tropics region of North Queensland. Several herbicides were effective on certain weed species, but lacked broad spectrum control. Better efficacy results from products with multiple active ingredients (i.e., imazapic-hexazinone) demonstrated the benefits of using mixtures of active ingredients to widen the spectrum of weed control efficacy. All tested pre-emergent herbicides behaved quite similarly in terms of their propensity for off-site movement in water (surface runoff losses generally >10% of active applied), with their losses largely driven by their application rate. Herbicides with lower application rates consistently contributed less to the total herbicide loads measured in surface runoff. Results demonstrated alternative choices from the more environmentally problematic herbicides (such as diuron) are available with effective alternative formulations providing between 4 and 29 times less risk than the traditional diuron-hexazinone ‘full rate’. However, considerable challenges still face canegrowers in making cost-effective decisions on sustainable herbicide selection. Additional research and effective grower extension are required to address information gaps in issues such as specific weed control efficacy of alternative herbicides and potential blending of some herbicides for more effective broad spectrum weed control, while also minimising environmental risks.

Cationic and anionic clay nanoformulations of imazamox for minimizing environmental risk

A synthesized anionic clay (layered double hydroxide or LDH) and a commercial cationic organoclay (Cloisite 10A, Clo10A) were assayed as host nanocarriers for imazamox (Imz) herbicide. Imz-LDH complexes were obtained by direct synthesis (DS) and regeneration (RE), whereas Imz-Clo10A complexes were prepared by ground mixing (GM) and through methanol addition (weak [WC] and strong [SC] complexes). Characterization of the complexes showed that Imz was partially hosted in the interlayer structure of the resulting nanoherbicides, as anion or as neutral molecule, with some of the herbicide at the external surfaces, depending on the carrier and preparation. The nanoherbicides showed a total water release from 73 (Imz-LDH DS) to 98% (Imz-Clo10A GM) with an immediate release from 67 (Imz-LDH DS) to 93% (Imz-Clo10A GM), while technical Imz released instantaneously >98%. The herbicide maximum concentration in the leachates from Imz-treated soil columns decreased between 20 and 35% for nanoherbicides with respect to the technical Imz, and between 10 and 30% with respect to a commercial Imz formulation. Total herbicide soil leaching losses were reduced from 95 or 98%, for technical and commercial Imz, to 77–67% for nanoherbicides. Bioassays showed similar efficacy for nanoherbicides and commercial product. The diverse Imz-clay complexes are revealed as smart delivery systems for this systemic herbicide by decreasing Imz water pollution risk while maintaining efficacy, with the advantages of their soil compatible matrix and the possibility to be located at action point in the subsoil.

Intensified dryland crop rotations support greater grain production with fewer inputs

Rising use and costs of agri-chemical inputs to support agricultural production have placed an economic burden on farmers while contributing to environmental and human health issues. Ecologically based nutrient and weed management – the use of ecological processes to replace external chemical inputs – may represent a strategy to support crop growth while achieving positive environmental and economic outcomes. In dryland agroecosystems around the world, farmers are increasingly transitioning toward no-till and intensified cropping systems, in which unvegetated fallow periods are replaced with crops. This study seeks to determine if cropping system intensification represents an ecologically based strategy for managing nutrients and weeds relative to traditional crop-fallow systems, and to understand the implications for crop production and profitability. We quantified total and potentially mineralizable nitrogen (N), arbuscular mycorrhizal fungal (AMF) colonization of wheat roots and implications for plant phosphorus (P) uptake, 6 years of crop yields, fertilizer and herbicide use, and net operating income across dryland, no-till cropping systems in the semi-arid High Plains, USA. Three levels of cropping system intensity were represented ranging from wheat-fallow (unvegetated fallow every other year) to continuous cropping (no fallow years). After accounting for variability due to environment and site characteristics, total and potentially mineralizable N were 12% and 30% greater in continuous rotations relative to wheat-fallow, respectively. Mid-intensity (fallow every 2 or 3 years) and continuous rotations had roughly 2 and 3 times more AMF colonization than wheat-fallow, respectively, and AMF colonization was positively correlated with wheat plant P concentration. Farmers practicing continuous cropping applied 22 and 34 kg ha−1 less N fertilizer per crop compared to wheat-fallow and mid-intensity, respectively, despite similar and 60% greater annualized crop production than mid-intensity and wheat-fallow rotations, respectively. Additionally, farmers who practiced continuous cropping used less than half the total herbicide used by wheat-fallow farmers. Net operating incomes of continuous and mid-intensity rotations were an estimated 47 USD ha−1 yr−1 (80%) and 42 USD ha−1 yr−1 (70%) more than wheat-fallow, respectively. These results suggest that cropping system intensification, and especially continuous cropping, represents an opportunity to achieve more grain production while managing weeds and nutrients with fewer agri-chemical inputs, leading to greater profitability and improved environmental outcomes in no-till agroecosystems.

Patterns of pre-crop glyphosate use and in-crop selective herbicide intensities in Northern Germany

Abstract We present a detailed analysis of glyphosate-based herbicide (GBH) use patterns with a dataset of herbicide use on arable farms in five districts of Northern Germany. Two aspects are focused: (1) The relationship between GBH and selective herbicides used on a specific field in the same cropping period and (2) the interplay of tillage, GBH and selective herbicide use in weed management. The most interesting result of our analysis is that the intensity of selective herbicide use for in-crop weed management was not related to GBH treatment prior to the crop (except maize). GBH treatments increased the total herbicide intensity on a field. Hence, using GBH pre-crop does not necessarily save herbicides in the following crop. GBH were additional treatments, not replacing selective herbicides. Our data was collected from different districts in Northern Germany extending from West to East. In the Eastern districts, a larger proportion of fields were treated with GBH. When a field was treated with GBH, it was applied with a similar intensity, regardless of the district. Hence, differences in GBH use patterns were caused only by the decision to treat pre-crop, while the intensity of these GBH treatments is hardly varied. In the Eastern districts, the higher proportion of fields treated with GBH is associated with larger proportion of fields with non-plough tillage. Non-plough fields were also treated more intensively with selective herbicides. Nevertheless, the use of both GBH and selective herbicides on the same field was more frequent and intensive in the Western districts of Northern Germany. We attribute the differences in pre-crop GBH use and in-crop selective herbicide use to regional production differences. Small to medium proportions of fields with both ploughing for primary tillage and pre-crop GBH use in all districts and most prominent in winter barley, winter wheat and maize indicate a luxurious, easy reducible use of GBH. We propose to promote farms with non- and low-use of GBH as an example of good practice.