Potential utilization ways of recovered chemical products from digestate

The study evaluates the potential application of chemical substances, obtained from biogas plants` by-products. Through the anaerobic digestion process with biogas the large amount of digestate is produced. This digestate mainly consists on the organic matter with the high concentration of nutrients such as nitrogen and phosphorus. During ammonia stripping and phosphorus precipitation the products- ammonia water, ammonium sulfate, ammonium nitrate, ferrous phosphate, aluminum phosphate, calcium phosphate and struvite can be recovered. These chemicals have potential application in different industrial sectors. According to Finnish market and chemicals properties, the most perspective industrial applications were determined. Based on the data, obtained through the literature review and market study, the ammonia water was recognized as a most perspective recovered substances. According to interview provided among Finnish companies, ammonia water is used for flue gas treatment in SNCR technology. This application has a large scale in the framework of Finnish industrial sectors. As well nitrogen with phosphorous can be used as a source of nutrients in the biological wastewater treatment plants of paper mills.

Influence of wheat straw and rhizosphere on seed germination, early seedling growth and bio-chemical attributes of Trianthema portulacastrum

Decomposing wheat (Triticum aestivum) straw and rhizosphere-infested soil were evaluated for their suppressive activity against horse purslane (Trianthema portulacastrum), a noxious summer weed in Pakistan. Two separate pot studies were carried out. Wheat straw was incorporated at 4, 6 and 8 g kg-1 soil five days before the sowing of horse purslane. Pots without straw incorporation were maintained as control. In a second study, soil was taken from 15 and 30 cm depths from a previously cropped wheat field immediately after its harvest and was used as growing medium. Soil from an intentionally uncropped area of the same field was used as control. Suppressive activity was measured in terms of germination dynamics, seedling growth, and biochemical attributes such as chlorophyll contents, total soluble phenolics, soluble protein and antioxidant enzymes. Germination, seedling growth, chlorophyll contents and soluble protein of horse purslane were all negatively influenced. Higher phenolics and enhanced activities of antioxidant enzymes were noticed in response to wheat residues incorporation and its rhizosphere soil. Both studies established that the phytotoxic influence of wheat straw and wheat-infested rhizosphere soil on horse purslane can further be exploited for horse purslane management as a sustainable approach.

Leaching of Picloram in ultisol under different rainfall volumes

The present study aimed to evaluate the leaching potential of Picloram in Ultisol columns under different rainfall amounts. For such, 30 treatments were evaluated (one soil associated with three levels of rainfall and ten depths).The experiments were arranged in a split-plot design, in a completely randomized design, with four replications. PVC columns of 10 cm in diameter and 50 cm in length were filled with these soils, moistened, and placed upright for 48 hours to drain the excess water. The herbicide was applied and rainfall simulations were carried out at specified intensities, according to the treatments, to force Picloram leaching. After 72 hours, all the columns were arranged in a horizontal position and opened lengthwise. Then, soil sampling was carried out every 5 cm of depth for subsequent herbicide extraction and quantification and analysis by high performance liquid chromatography. The remaining soil samples were placed in plastic pots, and, at the respective depths, the indicator species Cucumis sativus was sown. Twenty-one days after the emergence (DAE) of the indicator plants, evaluations were conducted to verify the symptoms of toxicity caused by Picloram in the plants. It was concluded that Picloram leaching is directly dependent on the volume of rain applied. The herbicide reached the deepest regions in the soil with the highest intensity of rain. The results obtained by bioassay were in agreement with those found by liquid chromatography.

Topochemistry of physical and chemical pretreatments of biomass as investigated by FE-SEM, XPS and ToF-SIMS

Surface chemistry is of great importance in plant biomass engineering and applications. The surface chemical composition of biomass which includes lignin, carbohydrates and extractives influences its interactions with chemical agents, such as pulp processing/papermaking chemicals, or enzymes for different purposes. In this thesis, the changes in the surface chemical composition of lignocellulosic biomass after physical modification for the improvement of resulting paper properties and chemical treatment for the enhancement of enzymatic hydrolysis were investigated. Low consistency (LC) refining was used as physical treatment of bleached softwood and hardwood pulp samples, and the surface chemistry of refined samples was investigated. The refined pulp was analysed as whole pulp while the fines-free fibre samples were characterized separately. The fines produced in LCrefining contributed to an enlarged surface specific area as well as the change of surface coverage by lignin and extractives, as investigated by X-ray photoelectron spectroscopy (XPS). The surface coverage by lignin of the whole pulp decreased after refining while the surface coverage by extractives increased both for pine and eucalyptus. In the case of pine, the removal of fines resulted in reduction of the surface coverage by extractives, while the surface coverage by lignin increased on fibre sample (without fines). In the case of eucalyptus, the surface coverage by lignin of fibre samples decreased after the removal of fines. In addition, the surface distribution of carbohydrates, lignin and extractives of pine and eucalyptus samples was determined by Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS). LC-refining increased the amounts of pentose, hexose and extractives on the surface of pine samples. ToF-SIMS also gave clear evidence about xylan deposition and reduction of surface lignin distribution on the fibre of eucalyptus. However, the changes in the surface chemical composition during the physical treatment has led to an increase in the adsorption of fluorescent whitening agents (FWAs) on fibres due to a combination of electro-static forces, specific surface area of fibres and hydrophobic interactions. Various physicochemical pretreatments were conducted on wood and non-wood biomass for enhancing enzymatic hydrolysis of polysaccharides, and the surface chemistry of the pretreated and enzymatically hydrolysed samples was investigated by field emission scanning electron microscopy (FE-SEM), XPS and ToF-SIMS. A hydrotrope was used as a relatively novel pretreatment technology both in the case of wood and non-wood biomass. For comparison, ionic liquid and hydrothermal pretreatments were applied on softwood and hardwood as well. Thus, XPS analysis showed that the surface lignin was more efficiently removed by hydrotropic pretreatment compared to ionic liquid or hydrothermal pretreatments. SEM analysis also found that already at room temperature the ionic liquid pretreatments were more effective in swelling the fibres compared with hydrotropic pretreatment at elevated temperatures. The enzymatic hydrolysis yield of hardwood was enhanced due to the decrease in surface coverage of lignin, which was induced by hydrotropic treatment. However, hydrotropic pretreatment was not appropriate for softwood because of the predominance of guaiacyl lignin structure in this material. In addition, the reduction of surface lignin and xylan during pretreatment and subsequent increase in cellulose hydrolysis by enzyme could be observed from ToF-SIMS results. The characterisation of the non-wood biomass (e.g. sugarcane bagasse and common reed) treated by hydrotropic method, alkaline and alkaline hydrogen peroxide pretreatments were carried out by XPS and ToF-SIMS. According to the results, the action for the removal of the surface lignin of non-wood biomass by hydrotropic pretreatment was more significant compared to alkaline and alkaline hydrogen peroxide pretreatments, although a higher total amount of lignin could be removed by alkaline and alkaline hydrogen peroxide pretreatment. Furthermore, xylan could be remarkably more efficiently removed by hydrotropic method. Therefore, the glucan yield achieved from hydrotropic treated sample was higher than that from samples treated with alkaline or alkaline hydrogen peroxide. Through the use of ToF-SIMS, the distribution and localization of lignin and carbohydrates on the surface of ignocelluloses during pretreatment and enzymatic hydrolysis could be detected, and xylan degradation during enzymatic hydrolysis could also be assessed. Thus, based on the results from XPS and ToF-SIMS, the mechanism of the hydrotropic pretreatment in improving the accessibility of enzymes to fibre and further ameliorating of the enzymatic saccharification could be better elucidated.

Physico-chemical characterization of nanoparticle coated paper

Förståelse av olika ytors vätningsegenskaper är viktig i många pappers-relaterade industriella processer eftersom vätningen påverkar materialbeteendet, t.ex. vid bestrykning, tryckning och laminering. Förmågan att kontrollera vätningen är av intresse, därför att den ger nya möjligheter till modifikation av ytor. Vätningen styrs av ytans struktur och kemi. Kunskap om dessa egenskaper krävs både i fundamentala studier och för industriella applikationer. Nanopartiklar används ofta för att skapa funktionella ytor med mångsidiga egenskaper. Detta arbete strävar till att förstå de fysikalisk-kemiska egenskaperna hos papper och kartong som är bestrukna med nanopartiklar, för att sedan kunna förklara de observerade förändringarna i ytornas vätningsförmåga. Funktionella ytor med justerbar vätningsförmåga tillverkades genom att deponera nanopartiklar i en rulle-till-rulle vätskeflammasprutningprocess (LFS). TiO2 -nanopartikelbeläggningen skapar en superhydrofob yta som har över 160° kontaktvinkelmed vatten, medan SiO2-nanopartikelbeläggningar skapar mycket hydrofila ytor med kontaktvinklar så låga som 21° med vatten. Superhydrofobiciteten eller hydrofiliteten är ett resultat av den kombinerade effekten hos ytstrukturen och ytkemin, såsom nanopartiklarnas oxidationsnivå eller karbonatiseringsnivå. Kartongytor som är bestrukna med TiO2-nanopartiklar kan vara såväl superhydrofoba som hydrofila. Hydrofilitet kan induceras genom UVA-strålning, medan behandling i hög temperatur i ugn resulterar i en superhydrofob yta. Ett mål med arbetet var att förstå mekanismerna hos de kemiska för ändringar som sker under UVA-bestrålning och värmebehandling av ytor, bestrukna med TiO2-nanopartiklar. Ytornas abrasions- och kompressionsmotstånd samt relaterade förändringar i funktionella egenskaper undersöktes. Resultaten skapar en bättre förståelse för potentiell användning av LFS-nanopartikelbeläggningar i pappersrelaterade applikationer. En förståelse för stabiliteten hos nanopartikelbeläggningarna när de exponeras för externa krafter är viktig för att försäkra deras funktionalitet i industriella applikationer och för att garantera beläggningarnas miljö-, hälso- och säkerhetsaspekter. ------------------------------------------ Pinnan kastumisominaisuuksien hallinta on tärkeää monissa paperiteollisuuden prosesseissa, sillä pinnan kastuminen vaikuttaa esimerkiksi päällystämiseen, painamiseen ja laminointiin. Pinnan kastuvuuden säätäminen avaa mielenkiintoisia uusia mahdollisuuksia pintojen ominaisuuksien hallintaan. Pinnan kastuvuus määräytyy pinnan rakenteesta ja kemiasta, ja näiden ominaisuuksien ymmärtäminen on tärkeää sekä perustutkimuksessa että teollisissa sovelluksissa. Nanopartikkeleita käytetään usein toiminnallisten ja hallitusti kastuvien pintojen aikaansaamiseksi. Tässä työssä on tarkasteltu nanopartikkelipinnoitetun paperin ja kartongin fysikaalis-kemiallisia pintaominaisuuksia, jotka selittävät havaittuja muutoksia pinnan kastuvuudessa. Toiminnalliset pinnat säädettävillä kastuvuusominaisuuksilla valmistettiin nesteliekkiruiskutus (LFS) nanopartikkelipinnoituksella rullalta rullalle-menetelmällä. TiO2-nanopartikkelipäällystys saa aikaan superhydrofobisen pinnan, jonka veden kontaktikulma on suurempi kuin 160°. Toisaalta SiO2-nanopartikkelipäällystys muuttaa pinnan hyvin hydrofiiliseksi, veden kontaktikulman ollessa vain 21°. Pinnan superhydrofobisuus tai hydrofiilisyys riippuu nanopartikkelipinnan rakenteesta ja pintakemiasta kuten pinnan hapettumisasteesta ja hiilipitoisuudesta. TiO2-nanopartikkelipinnoitetun kartonkipinnan kastumista voidaan säätää superhydrofobisen ja hydrofiilisen välillä. Pinnan hydrofiilisyys saadaan aikaan UVA-valolla, kun taas superhydrofobinen pinta voidaan palauttaa korkeassa lämpötilassa uunissa. Tämän työn tavoitteena oli selvittää, millaisia muutoksia TiO2-nanopartikkelipäällystetyn pinnan kemiassa tapahtuu UVA-valon ja lämpökäsittelyn vaikutuksesta. Työssä tarkasteltiin myös pinnan mekaanisen hankauksen ja kokoonpuristuksen vaikutusta toiminnallisiin ominaisuuksiin. Työssä saavutetut tulokset auttavat ymmärtämään LFS-nanopartikkelipäällystettyjen pintojen soveltuvuutta paperiin liittyvissä sovelluksissa. Nanopartikkelipäällystettyjen pintojen stabiilius ulkoisten voimien alaisena on tärkeää toiminnallisten päällystysten ympäristö-, terveys- ja turvallisuusnäkökulmia tarkasteltaessa.

Tolerance of sugarcane cultivars to chemical eradication

Knowledge of the minimum rate of glyphosate required to eradicate sugarcane ratoons can reduce the amount of herbicide used. To confirm this hypothesis, this study aimed to investigate the tolerance of different sugarcane cultivars to chemical eradication, at different glyphosate rates. The experiment was conducted in a randomized block design in a split-plot scheme, with four replications. The sugarcane cultivars (IACSP94-2094, IACSP94-2101, IACSP93-3046, IACSP94‑4004, IAC86-2480, and RB72454) were allocated in plots and the glyphosate rates (0, 1,440, 2,160, 2,880, 3,600, and 4,320 g ha-1), in the sub plots. The traits evaluated were signs of poisoning symptoms; total chlorophyll content, plant height, percentage of dead tillers, and dry weight of the plants. At 45 days after application (DAA), the glyphosate rate of 1,440 g a.e. ha-1 eradicated the cultivars IACSP94-2094 and IACSP94-2101, as well as RB72454 with application of 2,160 g a.e. ha‑1. Application of glyphosate 2,880 g a.e. ha-1 eradicated both IACSP93-3046 and IAC86-2480 and glyphosate 3,600 g a.e. ha-1 eradicated IACSP94-4004. The most tolerant cultivar was IACSP94‑4004, eradicated at the rate of 3,600 g. a.e. ha-1. This confirms the hypothesis that knowing the cultivar's tolerance leads, in practice, to a smaller amount of herbicide applied to the environment, which also reduces production costs.

Selective leaching of multimetal tailings

Depletion of high grade mineral resources, tightening of environmental regulations and the environmental impact of acid mine drainage caused by sulfidic minerals continuously increase the interest in processing tailings and other mine waste. Treating waste requires additional capital and operational input, but the decrease in size and need of tailings ponds and permits decrease the overall costs. Treatment and utilization of the tailings could also bring added revenue by the recovery of valuables. Leaching of metal sulfides is very demanding and time consuming and hence process conditions need to be carefully optimized. The leaching of sulfides is affected by for example the choice of leaching agent, its concentration and temperature, pH, the redox potential, pressure, pulp density and particle size distribution. With reference to the mine case study the leaching of nickel and copper sulfides, especially the primary minerals pentlandite and chalcopyrite were investigated. Leaching behavior and recoveries for nickel, copper and iron were found out by sulfuric and citric acid leaching experiments using tailings samples of high and low sulfur content. Moderate recoveries were obtained and citric acid seemed more attractive. Increase in temperature and decrease in pulp density had positive effect on the recovery and pH was also proven to have a significant effect on the recovery of valuables. The rate determining step was determined through kinetic modeling in case of all valuables separately. Leaching was controlled by diffusion. The investigated multimetal tailing showed moderate potential in recovering of metal valuables from low grade tailing deposits. The process conditions should however be further optimized.

Chemical control of morning glory as a function of water restriction levels

Among the herbicides recommended for the dry season and registered to sugarcane crop, amicarbazone, isoxaflutole and the association diuron + hexazinone + sulfomethuron-methyl can be highlighted. These are pre-emergence herbicides efficient against broad-leaved weeds. Morning glory causes large losses in infested sugarcane fields by bending the stalks and interfering in harvesting. In this study the effectiveness of pre-emergence herbicides for two species of morning glory (Ipomoea hederifolia and Ipomoea grandifolia) was evaluated. Treatments were arranged in completely randomized factorial design (4 x 7). There were four periods of water restriction (0, 30, 60 and 90 days), seven chemical treatments [diuron + hexazinone + sulfometuron-methyl (1387 + 391 + 33.35 g a.i. ha-1), diuron + hexazinone + sulfometuron-methyl (1507.5 + 425 + 36.25 g a.i. ha-1), diuron + hexazinone + sulfometuron-methyl (1658.25 + 467.5 + 39.87 g a.i. ha-1), diuron + hexazinone + sulfometuron­methyl (1809 + 510 + 43.5 g a.i. ha-1), amicarbazone (1190 g a.i. ha-1), amicarbazone + isoxaflutole (840 + 82.5 g a.i. ha-1)] and a control with no application. At 7, 14, 21 and 28 days after the restoration of moisture, control was visually evaluated. After the final evaluation, the dry mass of morning glories was measured. At 90 days of water restriction, diuron + hexazinone + sulfometuron-methyl was more effective to control I. hederifolia than the amicarbazone + isoxaflutole tank mixture. The four diuron + hexazinone + sulfometuron­methyl doses have reduced morning glory dry mass to zero; whereas treatments with amicarbazone have not. The most effective treatment for morning glory control was diuron + hexazinone + sulfometuron-methyl. This result may be due to a possible synergistic interaction.

Sorption and desorption of Suflafenacil in two soils in the state of São Paulo with different physical and chemical attributes

A study was conducted to evaluate the sorption and desorption of 14C herbicide saflufenacil (pyrimidinedione) in two soils in the State of São Paulo, classified as Red Yellow Latosol with clayey texture (LVA-1) and medium texture (LVA-2), using the batch method through isotherms. The soils were air dried and sieved a 2 mm mesh. The radioactivity was determined by liquid scintillation spectrometry in acclimatized room (25 ± 2 °C). Sorption isotherms were conducted for 5 concentrations of saflufenacil (5.0; 2.5; 1.0; 0.5 and 0.05 μg mL-1) and the results were adjusted to the Freundlich equation, thus obtaining the parameters of sorption followed by two extractions with 0.01 M CaCl2 to determine desorption parameters similarly to sorption. The results showed that saflufenacil sorption was low for both soils studied, being greater for the LVA with higher organic matter content. The desorption coefficients were greater than their sorption coefficients, suggesting the occurrence of hysteresis. The sorption and desorption isotherms (classified as type C isotherms), hysteresis and the t-test between the angular coefficient of the respective isotherms showed that both the sorption and desorption occur with equal intensity.

Chemical control of Pileamicrophylla in cattleya seedlings (Cattleyatenebrosa x Cattleyaleopoldy)

Species of the orchidaceae family are grown for marketing flowers and among them the genus Cattleya stands out. However, due to its slow growth, the substrate is subjected to weed infestation. Therefore, this study aims to evaluate the selectivity and efficiency of herbicides in controlling Pilea microphylla in Cattleya orchid seedlings (Cattleya tenebrosa x Cattleya leopoldy). We used a completely randomized design with four replications. The evaluated herbicides were oxyfluorfen (0, 120, 240 and 480 g ha-1), flumioxazin (0, 12.5, 25 and 40 g ha-1), nicosulfuron (0, 20, 40 and 80 g ha-1) mesotrione (0, 96, 144 and 192 g ha-1), clethodim (0, 60, 84 and 108 g ha-1) and metsulfuron-methyl (0, 1.2, 1.8 and 2.4 g ha-1). At post-emergence applying time, the Cattleya plants had three bulb sand were 10 cm tall, while P. microphylla, where 5 cm tall. Nicosulfuron, mesotrione and clethodim herbicides did not control P. microphylla, while oxyfluorfen and flumioxazin showed over 90% efficiency level sin controlling P. microphyllafrom 14 days after application (DAA). As to metsulfuron-methyl, it showed efficiency superior to 90% from the control dose of 1.8 g ha-1 at 28 DAA. All herbicides were selective plants of Cattleya, however, only oxyfluorfen, flumioxazin and metsulfuron-methyl were effective in controlling P. microphylla.

Effects of straw decomposition degree on leaching and weed control efficacy of tebuthiuron and hexazinone in green sugarcane harvesting

Green sugarcane harvesting may promote great changes in the dynamics of herbicides in the environment. Our goal was to evaluate the influence of straw decomposition degree on leaching and weed (Ipomoea grandifolia) control efficacy by (14C) tebuthiuron and hexazinone. The presence of straw on the soil surface affected leaching, mainly for hexazinone (leaching reduced from 37 to 5% of the applied amount in the presence of straw). Overall, tebuthiuron showed more efficient control of Ipomoea than hexazinone. The straw decomposition degree affected only hexazinone efficacy that was lowest for the least decomposed straw. Further studies are needed to evaluate the effects of sugarcane straw on herbicides dissipation, particularly on volatilization and photolysis, to better predict their efficacy and environmental fate.

Selectivity of chemical weed control systems in conventional cotton

Cotton is highly susceptible to the interference imposed by weed community, being therefore essential to adopt control measures ensuring the crop yield. Herbicides are the primary method of weed control in large-scale areas of production, and usually more than one herbicide application is necessary due to the extensive crop cycle. This study aimed to evaluate the selectivity of different chemical weed control systems for conventional cotton. The experiment took place in the field in a randomized block design, with twenty nine treatments and four replications in a split plot layout (adjacent double check). Results showed that triple mixtures in pre-emergence increased the chance of observing reductions in the cotton yield. To avoid reductions in crop yield, users should proceed to a maximum mixture of two herbicides in pre-emergence, followed by S-metolachlor over the top, followed by one post-emergence mixture application of pyrithiobac-sodium + trifloxysulfuron-sodium.

Chemical control of different Digitaria insularis populations and management of a glyphosate-resistant population

This study aimed to control different populations of Digitaria insularisby glyphosate herbicide, isolated and mixed, besides the combination of methods (chemical and mechanical) to manage resistant adult plants. Three experiments were conducted, one in pots which were maintained under non-controlled conditions and two under field conditions. In the experiment in pots, twelve populations of D. insularis were sprayed with isolated glyphosate (1.44 and 2.16 kg a.e. ha-1) and mixed (1.44 and 2.16 kg a.e. ha-1) with quizalofop-p tefuryl (0.12 kg i.a. ha-1). The treatment of 1.44 kg a.e. ha-1 of glyphosate plus 0.12 kg a.i. ha-1 of quizalofop was sufficient for adequate control (>95%) of all populations. Population 11 (area of grain production in Itumbiara, GO) was considered sensitive to glyphosate. Others populations were moderately sensitive or tolerant to the herbicide. In the field, the plants of D. insularis of one of the experiments were mowed and, in the other, there were not. Eight treatments with herbicides [isolated glyphosate (1.44 and 2.16 kg a.e. ha-1) and mixed (1.44 and 2.16 kg a.e. ha-1) with quizalofop-p-tefuryl at 0.12 kg a.i. ha-1), clethodim at 0.108 kg a.i. ha-1) or nicosulfuron at 0.06 kg a.i. ha-1)] were assessed, in combination with or without sequential application of the standard treatment, sprayed 15 days after the first application. The combination of the mechanic control with the application of glyphosate (2.16 and 1.44 kg a.e. ha-1) plus quizalofop-p-tefuryl (0.12 kg a.i. ha-1) or clethodim (0.108 kg a.i. ha-1), associated to the sequential application, was the most effective strategy for the management of adult plants of resistant D. insularis.

Leaching of Atrazine in Commercial and Xerogel Formulations in Oxisol Using Bioassay and Chromatographic Methods

Mobility of atrazine in soil has contributed to the detection of levels above the legal limit in surface water and groundwater in Europe and the United States. The use of new formulations can reduce or minimize the impacts caused by the intensive use of this herbicide in Brazil, mainly in regions with higher agricultural intensification. The objective of this study was to compare the leaching of a commercial formulation of atrazine (WG) with a controlled release formulation (xerogel) using bioassay and chromatographic methods of analysis. The experiment was a split plot randomized block design with four replications, in a (2 x 6) + 1 arrangement. The main formulations of atrazine (WG and xerogel) were allocated in the plots, and the herbicide concentrations (0, 3200, 3600, 4200, 5400 and 8000 g ha-1), in the subplots. Leaching was determined comparatively by using bioassays with oat and chromatographic analysis. The results showed a greater concentration of the herbicide in the topsoil (0-4 cm) in the treatment with the xerogel formulation in comparison with the commercial formulation, which contradicts the results obtained with bioassays, probably because the amount of herbicide available for uptake by plants in the xerogel formulation is less than that available in the WG formulation.

CHEMICAL CONTROL OF WHITE CLOVER IN SOYBEAN CROPS

ABSTRACTWhite clover is tolerant to many herbicides, making difficult a chemical control of this species during soybean crop establishments. The objective of this research was to select herbicides applied postemergence to control white clover in soybean and know the effects of this control on soybean yield. Seven herbicides were assessed, applied postemergence, with or without sequential application of glyphosate, and two control treatments (no control and total control of white clover). Glyphosate (with two sequential applications), fomesafen (with a sequential application of glyphosate), chlorimuron-ethyl and lactofen have shown a satisfactory control of white clover (above 80%). The lower control efficiency has resulted in lower production of soybeans.