Quantification of penoxsulam in soil and rice samples by matrix solid phase extraction and liquid-liquid extraction followed by HPLC-UV method

Dissipation of bispyribac sodium in aridisols: Impact of soil type, moisture and temperature

The study was conducted to evaluate the influence of physicochemical properties of soil, moisture and temperature on the dissipation behaviour of bispyribac sodium under laboratory conditions. Bispyribac sodium residues were extracted using matrix solid phase dispersion and were quantified using liquid chromatography tandem-mass spectrometry. The mean percent recovery of bispyribac sodium from studied soils ranged from 82.7 ± 8.3-105.1± 2.6%. The limit of quantification and limit of detection was 0.006 and 0.002 µg g^-1, respectively. Dissipation of bispyribac sodium followed first order kinetics and soil type greatly influenced the dissipation behaviour of bispyribac sodium. Dissipation was faster in loam soil (DT₅₀ = 12.79-14.52days) followed by clay loam (DT₅₀ = 22.01-23.15days), sandy loam (DT₅₀ = 23.34-25.17 days) and loamy sand soil (DT₅₀ = 25.39-27.32days). The amendment of soil with FYM enhanced the dissipation of bispyribac sodium by 1.86-5.96-fold. It dissipated slowly under submerged (DT₅₀ = 21.41-40.96days) conditions as compared to field capacity (DT₅₀ = 12.79-27.32days) in studied soils. The degradation rate increased with the increase in temperature in studied soils and DT₅₀ ranged from 12.79 to 40.96, 7.36-36.96 and 4.09-31.61days at 30, 40 and 50 °C, respectively.

Effect of Soil Type, Moisture and Temperature on the Dissipation of Penoxsulam in Soil Under Laboratory Conditions

A comprehensive study was conducted to evaluate the effect of concentration, moisture conditions, temperature and soil type on dissipation of penoxsulam in soil under laboratory conditions. Penoxsulam residues from the soil were extracted using matrix solid phase dispersion method and quantified using high performance liquid chromatography with UV detector at 230 nm. Dissipation followed first order kinetics and penoxsulam dissipated within 60 days in all the treatments with half-life varying from 12.60 to 30.08 days. Soil type greatly influenced the dissipation of penoxsulam and it was found to be slower in clay loam followed by loam, sandy loam and loamy sand soil. However, irrespective of soil type, dissipation of penoxsulam increased with increase in moisture content of soil and temperature.

Influence of Long Term Application of Butachlor on its Dissipation and Harvest Residues in Soil and Rice

The study delineates the effect of repeated application of butachlor to rice crop from 1997 onwards. Additionally, in 2014 and 2015, dissipation kinetics of butachlor in soil was studied under field and laboratory conditions. The average recovery of butachlor for soil, rice grain and rice straw ranged between 80.3%-93.2% and 82.8%-96.5% with quantification limit of 0.01 and 0.003 µg g^-1 for HPLC and GC-MS/MS, respectively. The dissipation of butachlor followed first order kinetics and half-life under long term field trials in rice soil varied from 15.2 to 19.29 days and 25.94 to 29.79 days under field and laboratory conditions, respectively. The residue of butachlor in soil, rice grain and straw samples at harvest over the years was below the quantification limit and no quantifiable amount of metabolites were present in soil at harvest suggestive of its safe application.