Relative Dissipation of Acetochlor, Alachlor, Metolachlor, and SAN 582 from Three Surface Soils

1999 ◽  
Vol 13 (2) ◽  
pp. 341-346 ◽  
Author(s):  
Thomas C. Mueller ◽  
David R. Shaw ◽  
William W. Witt
Keyword(s):  
Soil Moisture ◽  
Weed Control ◽  
Half Life ◽  
Soil Surface ◽  
Growing Season ◽  
Sampling Interval ◽  
Relative Order ◽  
Sampling Depth ◽  
Herbicide Degradation ◽  
Southern States

The dissipation of four commonly used soil-applied herbicides was examined in a standardized field experiment in three southern states (Kentucky, Mississippi, and Tennessee). Averaged over the three soils and 2 yr, the relative order of increasing half-life defined as time for 50% disappearance in days (DT50) was acetochlor (6.3 d) = alachlor (6.3 d) = SAN 582 (7.3 d) < metolachlor (13.7 d). Metolachlor was the most persistent in the soil surface, and this could potentially translate into greater duration of weed control into the growing season. All examined herbicides had a DT50that averaged less than 14 d in all states in both years, so full-season weed control of susceptible species would not be expected. Rapid herbicide degradation was encouraged in these field sites by adequate to excessive soil moisture and warm temperatures throughout the sampling interval. The soils also were light textured, and the lower adsorption of the herbicide allowed for degradation ease and perhaps leaching below the sampling depth.

scholarly journals The dependence of maize (Zea mays) hybrids yielding potential on the water amounts reaching the soil surface

Genetika ◽  
2013 ◽  
Vol 45 (1) ◽  
pp. 261-272 ◽  
Author(s):  
Branka Kresovic ◽  
Vesna Dragicevic ◽  
Bosko Gajic ◽  
Angelina Tapanarova ◽  
Borivoj Pejic
Keyword(s):  
Zea Mays ◽  
Soil Moisture ◽  
Block Design ◽  
Soil Surface ◽  
Growing Season ◽  
Maize Hybrids ◽  
Water Capacity ◽  
Set Up ◽  
Water Amount

The aim of the present study was to observe the response of maize hybrids under rainfed and irrigation conditions of the soil in order to establish the dependence of yielding potential on the water amounts reaching the soil surface during the growing season. The four-replicate trail was set up according to the randomised complete-block design on chernozem. Pre-watering soil moisture was approximately 70% of field water capacity, and soil moisture was established thermogravimetrically. During the five-year studies, the following differences in yields could be as follows: 12.68 t ha-1 (ZP 341); 12.76 t ha-1 (ZP 434); 13.17 t ha-1 (ZP 578); 14.03 t ha-1 (ZP 684) and 13.75 t ha-1 (ZP 704) under conditions of 440 mm, 440 mm, 424 mm, 457 mm and 466 mm of water, respectively. The hybrid ZP 341, i.e. ZP 578 expressed the highest, i.e. the lowest tolerance in dry relative seasons, respectively. The reduction of the water amount for every 10 mm decreased the yield by 119.4 kg ha-1 (ZP 341), 156.7 kg ha-1 (ZP 434), 172.3 kg ha-1 (ZP 578), 148.9 kg ha-1 (ZP 684) and 151.1 kg ha-1 (ZP 704).

Laboratory and field studies on the degradation of fipronil in a soil

Soil Research ◽  
2002 ◽  
Vol 40 (7) ◽  
pp. 1095 ◽  
Author(s):  
Guang-Guo Ying ◽  
Rai Kookana
Keyword(s):  
Soil Moisture ◽  
Half Life ◽  
Soil Moisture Content ◽  
Soil Surface ◽  
Field Studies ◽  
Transformation Product ◽  
Laboratory Studies ◽  
The Third ◽  
High Soil Moisture ◽  
Sulfone Derivatives

Degradation of a new insecticide/termiticide, fipronil, in a soil was studied in the laboratory and field. Three metabolites of fipronil (desulfinyl, sulfide, and sulfone derivatives) were identified from soils after treatment. Laboratory studies showed that soil moisture content had a great effect on the degradation rate of fipronil and products formed. High soil moisture contents (>50%) favored the formation of a sulfide derivative of fipronil by reduction, whereas low soil moisture (<50%) and well-aerated conditions favored the formation of fipronil sulfone by oxidation. Microorganisms in soil accelerated the degradation of fipronil to sulfide and sulfone derivatives. The third transformation product, a desulfinyl derivative, was formed by photodecomposition of fipronil in water and on the soil surface under sunlight. The desulfinyl derivative degraded rapidly in field soils with a half-life of 41–55 days compared with an average half-life of 132 days for fipronil. The half-life of the 'total toxic component' (fipronil and its metabolites) in field soil was 188 days on average.

Effect of Crop Presence on Persistence of Atrazine, Metribuzin, and Clomazone in Surface Soil

Weed Science ◽  
1996 ◽  
Vol 44 (3) ◽  
pp. 698-703 ◽  
Author(s):  
Kent Gallaher ◽  
Thomas C. Mueller
Keyword(s):  
Soil Moisture ◽  
Water Content ◽  
Soil Water Content ◽  
Half Life ◽  
Surface Soil ◽  
Growing Season ◽  
Soil Microbial Activity ◽  
Soil Microbial ◽  
Herbicide Concentration ◽  
The Difference

Atrazine, metribuzin, and clomazone half-lives averaged over treatments and seasons were approximately 27, 22, and 55 d, respectively. Clomazone dissipation was not affected by the presence or absence of a soybean crop. Atrazine and metribuzin dissipation was not affected by crops in 1992, but was more rapid in no-crop plots than in cropped plots in 1993. The difference may have been the result of higher soil water content with no-crop (a few weeds present) in 1993 than either corn or soybean. Lower soil moisture may have slowed soil microbial activity, thus suppressing atrazine and metribuzin degradation in the 1993 growing season. Few significant correlations were found between herbicide half-life or herbicide concentration and cocklebur growth, although one would expect these to be an index of activity.

Efficacy and Dissipation of Pyroxasulfone and Three Chloroacetamides in a Tennessee Field Soil

Weed Science ◽  
2011 ◽  
Vol 59 (4) ◽  
pp. 574-579 ◽  
Author(s):  
Thomas C. Mueller ◽  
Lawrence E. Steckel
Keyword(s):  
Weed Control ◽  
Half Life ◽  
Dissipation Rate ◽  
Resistance Management ◽  
Growing Season ◽  
Field Studies ◽  
Poor Correlation ◽  
Field Soil ◽  
Rainfall Patterns ◽  
Residual Control

Field studies were conducted in Knoxville, TN, over a 2-yr period (2007 and 2008) to determine the field dissipation rate and efficacy of pyroxasulfone, acetochlor, dimethenamid, ands-metolachlor to broadleaf signalgrass. Depending on rainfall patterns, pyroxasulfone at 209 g ai ha−1provided broadleaf signalgrass control of > 75%, which was equal to or superior to acetochlor at 1,740 g ai ha−1, dimethenamid at 1,500 g ai ha−1ands-metolachlor at 1,420 g ai ha−1. Pyroxasulfone provided residual control into the growing season and provides a tool for resistance management of later-emerging weeds. Herbicide dissipation was rapid in all soils (half-life usually < 20 d), although it was slower in a dry year. The order of herbicide dissipation and half-life in days in the 2 yr was acetochlor (3.5, 5 d) > dimethenamid (5, 9 d) >s-metolachlor (8.8, 27 d) > pyroxasulfone (8.2, > 71 d). There was poor correlation between observed weed control at 45 d after treatment and chemically determined herbicide concentrations at that same time, with ∼ 40% difference in 2007 and ∼ 50% difference in 2008.

scholarly journals Forage Legume Establishment under Exposure to Progressive Declines in Aminocyclopyrachlor and Aminopyralid in Temperate Pastures

Agronomy ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 392
Author(s):  
Amanda J. Miller ◽  
Vagner M. Leite ◽  
Linda M. Hall ◽  
Edward W. Bork
Keyword(s):  
Weed Control ◽  
White Clover ◽  
Half Life ◽  
Late Summer ◽  
Residual Effects ◽  
Pasture Production ◽  
Herbicide Degradation ◽  
Temperate Pastures ◽  
Negative Impacts

Legumes such as alfalfa (Medicago sativa L.) and white clover (Trifolium repens L.) increase forage productivity and quality in northern temperate pastures, but require re-establishment following broadleaf weed control using herbicides. To quantify the residual effects of two herbicides (aminocyclopyrachlor and aminopyralid) on potential legume re-establishment we examined alfalfa and clover recruitment at two field sites over two years. Sites were over-seeded with alfalfa and clover to populate the seed bank, and then sprayed with herbicide, after which seedling densities were monitored in late summer and fall of the current growing season. Defoliation (via mowing) effects were also assessed to evaluate the role of vegetation competition on legume establishment. Herbicides were applied at recommended rates (1.0), and 0.5, 0.25, 0.125, 0.0625, and 0 times recommended field rates, emulating exponential herbicide degradation (one through four half-lives). Alfalfa and white clover seedling densities were negatively impacted by all rates of herbicide, with modestly greater negative impacts from aminopyralid than aminocyclopyrachlor, although responses to herbicides remained site and legume specific. Reductions in alfalfa and clover were particularly evident through the 0.25 (i.e., two half-life) herbicide rate, with reductions in alfalfa ranging from 78% to 95%, and in clover from 73% to 88%. Legume densities at the 0.125 (three half-life) rate were 39%–68% lower than those in nonsprayed control plots. Our results suggest that at least three half-lives of degradation must occur, and likely four or more, before these legumes can re-establish at densities acceptable for pasture production. These findings have implications for producers seeking to promptly re-establish forage legumes within pastures sprayed for broadleaf weed control in northern temperate regions.

Seasonal changes in the germination responses of buried seeds of Barbarea vulgaris

1989 ◽  
Vol 67 (7) ◽  
pp. 2131-2134 ◽  
Author(s):  
Jerry M. Baskin ◽  
Carol C. Baskin
Keyword(s):  
Soil Moisture ◽  
Seasonal Changes ◽  
Soil Surface ◽  
Growing Season ◽  
Barbarea Vulgaris ◽  
Buried Seeds

In light, fresh seeds of Barbarea vulgaris germinated to 33–62% at 30:15 and 35:20 °C, and 0–5% at 15:5, 20:10, and 25:15 °C; in darkness, they germinated to 0–5% at all thermoperiods. Seeds were buried in pots of soil in mid-July 1983 and 1984 and kept in a greenhouse without temperature controls. Beginning on 1 August, seeds were exhumed monthly for 26.5 (1983 seeds) and 30.5 (1984 seeds) months and tested in light and darkness over the range of thermoperiods. Seeds after-ripened rapidly during the first 2 weeks of burial, and in August they germinated to 65 – 100% at all thermoperiods in light, but to only 0–3% in darkness. Throughout the study, seeds tested in light at the respective monthly thermoperiod germinated to 83 – 100% from April to October and to 45 – 100% in November and March. Thus, seeds brought to the soil surface at any time during the growing season can germinate when soil moisture is nonlimiting. Exhumed seeds germinated to 1 – 77% in darkness at July and August temperatures (35:20 °C) during July and August; however, they did not germinate while buried.

scholarly journals (343) Weed Controlin Vineyard Following Fall and Spring Application of Selected Herbicide Combinations

HortScience ◽  
2005 ◽  
Vol 40 (4) ◽  
pp. 1024E-1025
Author(s):  
Sorkel Kadir ◽  
Kassim Al-Khatib
Keyword(s):  
Weed Control ◽  
Residual Activity ◽  
Growing Season ◽  
Early Spring ◽  
Herbicide Application ◽  
Herbicide Degradation ◽  
Warm Weather ◽  
Weed Emergence ◽  
Fall Application

Soil residual herbicides registered for use on grapes can be applied from fall to spring, before weed emergence. However, ample early-spring moisture and warm weather may enhance weed emergence before herbicide application in the spring and prevent timely application. Therefore, fall application of herbicides can be beneficial if herbicides would provide adequate weed control in the following spring. Warm and wet winters may enhance herbicide degradation and shorten herbicide residual activity that result in poor weed control the following spring. Fall and spring application of oryzalin or norflurazon applied alone or in combination with diuron, simazine, or oxyfluorfen were evaluated for weed control in commercial vineyards at Oskaloosa and Eudora in northeast Kansas in 2003 and 2004. Weeds were not controlled adequately with oryzalin or norflurazon applied alone. At the end of the growing season, however, weed control was greater with spring than fall application. In addition, weed control with norflurazon was slightly greater than oryzalin. Norflurazon or oryzalin applied in combination with simazine, diuron, or oxyfluorfen controlled more weeds than norflurazon or oryzalin applied alone. The greatest control was with norflurazon or oryzalin applied with oxyfluorfen. In general, all herbicide combinations applied in the spring and fall provided similar weed control 4 months after spring application. However, at the end of the growing season, weed control was 10% to 20% greater when herbicides applied in the spring than fall. This study showed that acceptable weed control can be achieved when norflurazon or oryzalin is applied with oxyfluorfen and diuron in the fall.

Atrazine degradation and transport in runoff on a Black Vertosol

Soil Research ◽  
2007 ◽  
Vol 45 (8) ◽  
pp. 598 ◽  
Author(s):  
D. J. Rattray ◽  
J. Standley ◽  
D. M. Silburn ◽  
D. M. Freebairn ◽  
K. P. Spann
Keyword(s):  
Potassium Chloride ◽  
Weed Control ◽  
Half Life ◽  
Cultural Practices ◽  
Total Concentration ◽  
Soil Surface ◽  
Runoff Water ◽  
Initial Application ◽  
Atrazine Concentration ◽  
Guideline Value

In Australia communities are concerned about atrazine being detected in drinking water supplies. It is important to understand mechanisms by which atrazine is transported from paddocks to waterways if we are to reduce movement of agricultural chemicals from the site of application. Two paddocks cropped with grain sorghum on a Black Vertosol were monitored for atrazine, potassium chloride (KCl) extractable atrazine, desethylatrazine (DEA), and desisopropylatrazine (DIA) at 4 soil depths (0–0.05, 0.05–0.10, 0.10–0.20, and 0.20–0.30 m) and in runoff water and runoff sediment. Atrazine + DEA + DIA (total atrazine) had a half-life in soil of 16–20 days, more rapid dissipation than in many earlier reports. Atrazine extracted in dilute potassium chloride, considered available for weed control, was initially 34% of the total and had a half-life of 15–20 days until day 30, after which it dissipated rapidly with a half life of 6 days. We conclude that, in this region, atrazine may not pose a risk for groundwater contamination, as only 0.5% of applied atrazine moved deeper than 0.20 m into the soil, where it dissipated rapidly. In runoff (including suspended sediment) atrazine concentrations were greatest during the first runoff event (57 days after application) (85 µg/L) and declined with time. After 160 days, the total atrazine lost in runoff was 0.4% of the initial application. The total atrazine concentration in runoff was strongly related to the total concentration in soil, as expected. Even after 98% of the KCl-extractable atrazine had dissipated (and no longer provided weed control), runoff concentrations still exceeded the human health guideline value of 40 µg/L. For total atrazine in soil (0–0.05 m), the range for coefficient of soil sorption (Kd) was 1.9–28.4 mL/g and for soil organic carbon sorption (KOC) was 100–2184 mL/g, increasing with time of contact with the soil and rapid dissipation of the more soluble, available phase. Partition coefficients in runoff for total atrazine were initially 3, increasing to 32 and 51 with time, values for DEA being half these. To minimise atrazine losses, cultural practices that maximise rain infiltration, and thereby minimise runoff, and minimise concentrations in the soil surface should be adopted.

scholarly journals The fate of some pesticides in Finnish cultivated soils

1992 ◽  
Vol 1 (1) ◽  
pp. 37-55
Author(s):  
Hannu Braunschweiler
Keyword(s):  
Surface Layer ◽  
Half Life ◽  
Peat Soil ◽  
Soil Surface ◽  
Growing Season ◽  
Organic Soils ◽  
Growing Seasons ◽  
Mineral Soils ◽  
Cultivated Soils

The persistence and movement of methabenzthiazuron, metazachlor, trifluralin, iprodione, fenitrothion, fenvalerate and furathiocarb was studied in one growing season in cultivated clay, finesand and organic soils in southern Finland. Trifluralin was studied for two growing seasons. Methabenzthiazuron was the most mobile pesticide and metazachlor was almost as much mobile. They leached at least 15 cm in a month. Fenitrothion and fenvalerate were the most immobile. Trifluralin was the most and fenitrothion the least persistent. The concentrations of iprodione and fenvalerate in the top soils increased towards the autumn, presumably due to leaching of pesticides from plants. The residues of trifluralin measured in the surface layer of the mineral soils at the end of the growing season might have been harfmul to plants sensitive to trifluralin. The residues of trifluralin in the peat soil surface 1.5 years after the treatment were still high. Also methabenzthiazuron, iprodine and fenvalerate residues may in all probability have been detected in the following spring. If the half-life of a pesticide is over 80 - 100 days, it is likely that residues of it may be found in the spring following the application in cultivated Finnish soils.

Zero vs. conventional tillage and their effects on crop yield and soil moisture

1992 ◽  
Vol 72 (3) ◽  
pp. 679-688 ◽  
Author(s):  
S. A. Brandt
Keyword(s):  
Soil Moisture ◽  
Weed Control ◽  
Crop Production ◽  
Growing Season ◽  
Conventional Tillage ◽  
Future Research ◽  
Zero Tillage ◽  
Poor Seed ◽  
Seed Placement ◽  
Use Efficiency

A study comparing zero tillage (ZT) with conventional tillage (CT) crop production in two rotations; fallow–oilseed–wheat, and oilseed–wheat–wheat, was conducted during 1979–1990. In 36 comparisons of ZT with CT over three rotation phases and 12 yr, ZT increased spring soil moisture in nine cases and resulted in no decreases; increased yield in nine cases while decreasing yield in three; and increased moisture use efficiency in six cases with two decreases. Increases in spring soil moisture were not related to precipitation during the non-growing season but may have been influenced by weeds. Increased spring soil moisture with ZT occurred more frequently on fallow than on stubble, presumably because precipitation was greater. Yield increases with ZT generally occurred where spring soil moisture was increased and weeds were adequately controlled. Yield decreases with ZT were normally associated with poor weed control, but in one case poor seed placement with ZT reduced yield. Throughout the study, inadequate weed control with ZT was a major factor limiting responses. Implications of these results on future research required to improve adoption of this important soil–conserving practice are discussed.Key words: Zero tillage, wheat, canola, flax, available moisture, weeds

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