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Pyran oxadiazon in soil and soybean plants and grain residue analysis method and pyran oxadiazon residues in soybean fields, dynamic and different soil degradation. Residue analysis by HPLC-VWD as pyran grass ketone. Soil samples were extracted with methanol, concentrated constant volume, HPLC-VWD detection, in addition concentration level of 0.05 ~ 1mg/kg recovery of 86 to 88%, the relative standard deviation of 0.6 to 5.7%, minimum detection method concentration 0.005mg/kg; soybean plants and grain samples using methanol water extract used to adjust the PH value of liquid-liquid distribution method purifying samples, analytical HPLC-VWD, and then add the concentration level of 0.05 ~ 1mg/kg, the recovery rate of the method can be 74.2 to 89.4%, the relative standard deviation of 2.0 to 3.1%, the lowest detectable concentration of 0.01mg/kg. Good linear relationship of the two methods, the recovery rate is relatively high, the coefficient of variation is smaller. Through the two years of 2003 and 2004 field trials pyran oxadiazon degradation dynamics in soybean fields. Pyran metribuzin degradation in soil and plants in line with the first-order kinetics mode C = C-0e -kt , two years in the soil half-life were 3.08 and 2.83 days, the degradation of the equation is C = 0.1672e -0.2249t and C = 0.2361e , 0.2443t in soybean plants on the half-life of 2.44 and 2.85 days, degradation of the equation C = 5.6069e -0.2843t and C = 8.7596e -0.2438t ; to fast catching net EC1200 with 10% 2400ml/ha in the 2-3 leaf stage of soybean postemergence spraying once harvest samples collected, oxadiazon residues in soil pyran method were lower than the minimum detectable concentration 0.005mg/kg, the soybean seed pyran oxadiazon residues were below the minimum detectable concentration method 0.01mg/kg pyran metribuzin in soybean fields are readily biodegradable pesticides. Under laboratory conditions, the effects of the pyran oxadiazon four soil degradation dynamic, and found that the drug half-life of the shortest in the white pulp soil, meadow soil and chernozem degradation, followed by saline-alkali soil degradation half-lives the longest, the four soil half-life were 8.52,12.81,17.37 and 19.25 days. Regression analysis showed that the main factor of the ketone pyran-grass in soil degradation is pH and organic matter content of the soil, alkaline soil, the stronger the slower pyran oxadiazon degradation, the higher the organic matter content, drug degradation faster. Temperature the pyran grass ketone effects of soil degradation study found that four temperature pyran oxadiazon The meadow soil degradation half-life decreases with increasing temperature at 15 ° C and 25 ° C, 35 ° C, 45 ° C, the half-life were 18.05,12.56,2.46 and 0.76 days, when the temperature is too low, the pyran oxadiazon longer half-life, the half-life was decreased, the temperature rose too high, but to reduce the magnitude of less obvious, concluded that 25 ~ 35 ℃ pyran oxadiazon the optimum degradation temperature.
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