“超量”使用“莠去津”会使小麦减产

近年来，农田除草剂的施用节省了大量的劳动力，多种除草剂也被广大农民朋友所接受。但有些农民朋友由于对化学除草剂的知识还不太了解，一些农户由于超量喷施和施药方法不当，造成当年瓜果蔬菜不能正常生长，还给下茬作物造成减产。特别是部分农户在用含“莠去津”成分的除草剂给玉米地除草时，由于喷药过量对下茬小麦造成第二次药害。

Degradation of Herbicides Atrazine and Bentazone Applied Alone and in Combination in Soils

The application of a mixture of bentazone(3-isopropyl-1H-2,1,3-benzothiadiazin-4(3H)-one-2,2-dioxide)and atrazine (6-chloro-N2-ethyl-N4-isopropyl-1,3,5-triazine-2,4-diamine)is a practical approach to enhance the herbicidal effect.Labo- ratory incubation experiments were performed to study the degradation of bentazone and atrazine applied in combination and individually in maize rhizosphere and non-rhizosphere soils.After a lag phase,the degradation of each individual herbicide in the non-autoclaved soil could be adequately described using a first-order kinetic equation.During a 30-d in- cubation,in the autoclaved rhizosphere soil,bentazone and atrazine did not noticeably degrade,but in the non-autoclaved soil,they rapidly degraded in both non-rhizosphere and rhizosphere soils with half-lives of 19.9 and 20.2 d for bentazone and 29.1 and 25.7 d for atrazine,respectively.The rhizosphere effect significantly enhanced the degradation of atrazine, but had no significant effect on bentazone.These results indicated that biological degradation accounted for the degrada- tion of both herbicides in the soil.When compared with the degradation of the herbicide applied alone,the degradation rates of the herbicides applied in combination in the soils were lower and the lag phase increased.With the addition of a surfactant,Tween-20,a reduced lag phase of degradation was observed for both herbicides applied in combination. The degradation rate of bentazone accelerated,whereas that of atrazine remained nearly unchanged.Thus,when these two herbicides were used simultaneously,their persistence in the soil was generally prolonged,and the environmental contamination potential increased.

Control Effect of Different Concentrations of Herbicide Atrazine on Weed in Foxtail Millet Field

The control effect of different concentrations of herbicide atrazine （before seedling after sowing） on weed in foxtail millet field was compared, which provide theoretical basis for screening suitable herbicides concentration for foxtail millet production. As a result, after spraying 25 and 40 d, plant control effect and fresh weight control effect were best by 4 500 ml/hm^2 processing, and fresh weight control effect reached 83.16% and 86.43%. Compared with spraying water （CK）, yieldincreasing effect was the best in the treatment group with atrazine at 2 250 ml/hm^2, where yield growth rate was 54.31%, followed by the treatment group with atrazine at 3 000 ml/hm^2. Therefore, 2 250 ml/hm^2 was the optiaml concentration of herbicide atrazine for millet production.

Study on Weed Control and Safety of Tembotrione-Atrazine Tank Mixture in Spring Maize Fields

This study aimed to explore the effect of 5% tembotrione oil dispersion(OD)-38% atrazine suspension concentrate(SC) tank mixture on the weeds in spring maize fields and the safety of the mixture. To be specific, randomized block design was adopted for the field experiments. The results showed that the application of tankmixture of 5% tembotrione OD at 90 g a.i./hm^(2)and 38% atrazine SC at 570 g a.i./hm^(2)and the mixture of 5% tembotrione OD at 90 g a.i./hm^(2)and 38% atrazine SC at 1140 g a.i./hm^(2)respectively controlled 94.7%~96.3% and 94.0%~96.3% of the grass weeds, 94.7%~96.0% and 93.7%~95.7% fresh weight of grass weeds, 95.3%~96.3%and 93.3%~97.3% of broadleaf weeds, and 94.7%~96.0% and 93.3%~96.3% fresh weight of broadleaf weeds. The efficacy was better than that of the 5% tembotrione alone and the control herbicide and no phytotoxicity of the mixtures was identified.The tank mixture of tembotrione and atrazine should be promoted in the spring maize field for weed control and the recommended dosages were 90 g a.i./hm^(2)for 5%tembotrione and 570 g a.i./hm^(2)for 38% atrazine.

Control Effect of 80% Nicosulfuron·Atrazine Water-dispersible Granules on Weeds in Spring Maize Field

[Objective] This study aimed to investigate the control effect of different concentrations of 80% nicosulfuron·atrazine water-dispersible granules on weeds in spring maize field. [Method] Maize field was sprayed with 300, 375, 450, 750 g/hm280% nicosulfuron·atrazine water-dispersible granules respectively, with 40 g/L nicosulfuron suspending concentrate and 38% atrazine suspending concentrate as control agents. Artificial weeding and control(CK) plots were set. [Result] Fresh weight control efficiency of 375-750 g/hm280% nicosulfuron·atrazine water-dispersible granules was significantly higher than that of 40 g/L nicosulfuron suspending concentrate and 38% atrazine suspending concentrate; no obvious phytotoxicity symptoms were observed after application of 300-450 g/hm280% nicosulfuron·atrazine waterdispersible granules; 750 g/hm280% nicosulfuron·atrazine water-dispersible granules posed certain impact on the growth of maize seedlings. Compared with control plots, various doses of 80% nicosulfuron·atrazine water-dispersible granules significantly improved the yield of maize. [Conclusion] In the present study, 375-450 g/hm280% nicosulfuron·atrazine water-dispersible granules exhibited high control effect on weeds in maize field and were safe for the growth of maize seedlings.

Removal atrazine using two anion-exchange resins supported nanohydrous metal-oxide particle

Hydrous iron oxide and hydrous aluminum oxide were loaded successfully onto a polymeric adsorbent(D301) to modify adsorbing materials(HIOD301 and HAOD301). The adsorptive equilibrium of atrazine was investigated in an aquatic environment using HIOD301 and HAOD301 under different experimental conditions. The results indicated that both HIOD301 and HAOD301 showed good adsorption capacities for atrazine at p H 4. The Langmuir and Freundlich isotherm equations were used to study the interactions between the adsorbate and adsorbent.The adsorption kinetics of atrazine at different concentrations was well described in terms of a pseudosecond-order equation in regard to the correlation coefficients and adsorption capacity. The removal percentages of atrazine for HIOD301 and HAOD301 were still more than 95% in the presence of sodium chloride.

Sorption, Transport and Transformation of Atrazine in Soils,Minerals and Composts: A Review

Atrazine is a widely used herbicide for controlling weeds on both agricultural and nonagricultural land,which is equally detected in water supplies beyond safe concentrations.Although the presence of atrazine metabolites is an indication of herbicide degradation,some of them still exhibit toxicity,greater water solubility and weaker interaction with soil components than atrazine.Hence,studies with atrazine in the environment are of interest because of its potential to contaminate drinking water sources.Data on atrazine availability for transport,plant uptake,and microbial degradation and mineralization are therefore required to perform more comprehensive and realistic environmental risk assessments of its environmental fate.This review presents an account of the sorption-desorption phenomenon of atrazine on soil and other sorbents by revisiting the several mechanisms of atrazine-sorbent binding reported in the literature.The retention and transport of atrazine in soils;the influence of organic matter on atrazine sorption;the interactions of atrazine with humic substances,atrazine uptake by plants,atrazine bioccumulation and microbial degradation;atrazine transformation in composting environments;and finally atrazine removal by biosorption are discussed.

Sorption and Leaching Potential of Isoproturon and Atrazine in Low Organic Carbon Soil of Pakistan Under a Wheat-Maize Rotation

Pesticide leaching is a great threat in low organic carbon soils when subjected to improper irrigation scheduling.Limited data are available on the sorption and leaching potential of pesticides in agricultural soils of Pakistan with low soil organic carbon(SOC).Lysimeter and field studies were conducted with and without manure application at two irrigation levels in a wheat-fallowmaize rotation in Faisalabad,Punjab,Pakistan.Isoproturon was applied to wheat 55 d after sowing at 1 kg active ingredient(a.i.)ha^(-1),while atrazine was sprayed on maize 30 d after sowing at 0.774 kg a.i.ha^(-1).Soil was sampled from three depths(0-35,35-70,and 70-110 cm) for the field study and four depths(0-35,35-70,70-115,and 115-160 cm) for the lysimeter study,280 and 65 d after application of isoproturon and atrazine,respectively.The soil-water partition coefficients(K_d) of isoproturon and atrazine ranged from 0.3 to 1.2 and 0.4 to 1.5 L kg^(-1),respectively,and increased linearly with increase in SOC contents.The organic carbon-normalized soil-water partition coefficient(K_(oc)) of isoproturon and atrazine averaged 246.1 and 184.9 L kg^(-1),respectively,being higher with low spiking concentration.Isoproturon residues measured 280 d after application ranged from 2.1% to 3.6% of the applied mass in the lysimeter study and from 1.5% to 3.1% under field conditions.Atrazine residues 65 d after application ranged from only 0.62% to 0.78% and from 0.88% to 0.82% in the lysimeter and field studies,respectively.The lowest levels of residues for both pesticides were observed with frequent irrigation applied to manure-amended soil.A pesticide leaching risk screening tool,the ground water ubiquity score(GUS),indicated that in the absence of manure under both irrigation levels,isoproturon has a leaching potential(GUS = 2.8),while with the application of manure it has a very low leaching risk.Atrazine GUS ranged from 1.7 to 1.9,indicating a very low risk of leaching.