Evaluation of three pesticide leaching models with experimental data for alachlor, atrazine and metribuzin

Abstract

Summary The persistence and movement of residues of alachlor, alrazine and metribuzin were measured in a mini‐lysimeter system in the field. This comprised a number of soil columns (11 cm diametert; 30 cm long), and permitted the vertical distribution of residues to be determined at. intervals alter application and the collection and analysis of leaehale water. Laboratory experiments were also performed to determine the degradation rates of the three herbicides and their strengths of adsorption by the test soil. The results showed an order of degradation rate of metribuzin> alachlor>atrazine and an order of adsorption of alacblor>atrazine>melribuzin. Movement of residues in the soil columns and concentrations in the leachate were inversely related to the strength of adsorption. Parameters derived from the laboratory data were used in conjunction with weather data for the period of the field experiment in three mathematical models of pesticide leaching: VARLEACH, LEACHP and PRZM2. In most instances, the models gave acceptable predictions of the distribution of residues in soil. This was particularly so for the less mobile compound alachlor. With the most mobile compound, metribuzin, residues were not well predicted at the later sampling dates. All three models gave accurate predictions of the volumes of drainage water, but none of them predicted the concentrations of herbicide in the leachate, presumably because they do not take account of preferential flow pathways of water and solute in the soil.

Dissipation of Chlorpyrifos in a Malaysian Agricultural Soil: A Comparison between a Field Experiment and Simulation by the VARLEACH and PERSIST Models

“…The values were very close; however the predicted values were higher than the observed value for chlorpyrifos. This observation was similar to that reported by Walker (1996Walker ( , 1987, whereby the predicted values were overestimated. The degree of agreement between the predicted and the observed values was evaluated using the coefficient of residual mass (Halimah et al 2016b;Ismail et al 2015a;Maznah et al 2015).…”

“…The CRM value for PERSIST on the day of spray (Day 0) was 1, indicating that there is perfect agreement between the predicted and observed value Walker et al 1996). On the first, third and fifth day after treatment, the CRM value predicted by PERSIST was slightly higher compared to the observed values.…”

Plasmid Transfer between the Bacillus thuringiensis Subspecies kurstaki and tenebrionis in Laboratory Culture and Soil and in Lepidopteran and Coleopteran Larvae

“…1) that contained 0.9% organic carbon, 67.1% (vol/vol) sand, 16.6% (vol/vol) silt, and 16.3% (vol/vol) clay and had a pH of 6.8 (27). The second soil (Hunts Mill field) contained 1.91% organic matter, 75% (vol/vol) sand, 10% (vol/vol) silt, and 15% (vol/vol) clay and had a pH of 5.97 (26). The soil samples were sieved (mesh size, 2 mm), air dried at room temperature to a water content of 4% (wt/vol), and stored at 10°C until they were used.…”

Pesticide sorption and leaching potential on three Hawaiian soils

“…K oc (mL g À1 ) t 1/2 (days) References Barriuso et al (1997); Baskaran et al (1996);Ismail and Tet-Vun (2003); James et al (1995) Alachlor 57e457 e 21 8e200 e 13 Patakioutas and Albanis (2002); Sakaliene et al (2007); Sonon and Schwab (1995); Stolpe and Shea (1995); Walker et al (1996); Weed et al (1995); Yen et al (1994) Fig . 1.…”