Research ArticleReceived: 19 February 2013 Revised: 16 September 2013 Accepted article published: 13 December 2013 Published online in Wiley Online Library:

(wileyonlinelibrary.com) DOI 10.1002/ps.3707

Degradation kinetics of anilofos in soiland residues in rice crop at harvestShishir Tandon∗

Abstract

BACKGROUND: Pesticides used on rice, which is widely grown in India in the rainy season, must be investigated for thepersistence and magnitude of their residues in the crop and soil to ensure human and environmental safety. Anilofos is widelyused in rice, and its persistence and dissipation behaviour in soil and rice was investigated in field trials under subhumid andsubtropical conditions.

RESULTS: The persistence of anilofos in soil, husk, grain and rice straw was evaluated at two application rates (0.4 and 0.8 kg AIha−1) by RP-HPLC. In soil, residues were detected up to 45 and 75 days after application at 0.4 and 0.8 kg AI ha−1 respectively.No residue was observed in soil, husk, grain or rice straw at the time of harvest at either application rate. Detector response waslinear within the concentration range 0.1–5.0 µg mL−1 at 2.22% standard deviation. The limit of detection was 0.003 µg mL−1,and the limit of quantification of the method for soil, straw, grain and husk was 0.007, 0.01, 0.008 and 0.01 µg g−1 respectively.

CONCLUSION: The dissipation of herbicide from soil appeared to occur in a single phase and conformed to pseudo-first-orderkinetics. The calculated half-life values of anilofos residue in soil were 13 days for the lower rate of application (0.4 kg AI ha−1)and 15.5 days for the higher rate (0.8 kg AI ha−1). Anilofos residues were below the maximum residue level in soil, husk, ricegrain and rice straw at harvest.c© 2013 Society of Chemical Industry

Keywords: anilofos; rice; dissipation kinetics; residue analysis; HPLC

1 INTRODUCTIONDemand for rice (Oryza sativa L.) in India is expected to be140 million t by 2050.1 India, with 43 million ha, is the leadingrice-producing country and accounts for 20% of all world riceproduction and 45% of its total food grain production. InIndia, losses of food grain production through weeds alone invarious crops amount to about 33%, i.e. about $US 400 million.2

Productivity of rice is often limited by heavy weed flora, whichis very diverse under transplanting and direct-seeding conditions

and causes yield reductions of 15–90%.2–5 To protect the cropfrom the ravages of weeds, various control measures, such asmanual hand weeding and other control measures, are used,but they are difficult and require huge manpower. Chemicals arethe obvious alternative, an indispensable and cost-efficient weedcontrol practice that is widely practised by farmers.

A number of pre-emergence herbicides are applied forcontrolling weeds. Anilofos (S-{2-[(4-chlorophenyl)(1-methylethyl)amino]-2-oxoethyl}O,O-dimethyl phosphorodithioate) isan organophosphorous herbicide commercially available asemulsifiable concentrate, granules, dispersible powder andpremixes with 2,4-D and propanil. Anilofos has selectiveherbicidal pre- and/or post-emergence activity against grassesand sedges such as Cyprus difformis, Cyprus iria, Echinochloacrusgalli, Echinochloa colona, Eclipta alba, Fimbristylis spp., Marsiliaquadrifoliata, etc., in transplanted paddy rice and directly sownrice. It is also used in cotton, soybeans, corn, wheat, rapeseed andother crops for controlling weeds. Anilofos is basically absorbedthrough the roots and to some extent through newly emerging

shoots and young leaves. It is translocated through the meristemand severely inhibits cell growth and cell division of meristematictissue, which results in discolouring, stunted growth and deathof the weeds. According to the World Health Organisation (WHO)classification, it is a class II, moderately hazardous pesticide withmoderate toxicity to birds and low toxicity to fish and bees.6

Information on anilofos dissipation in soil and plants is limited

for subtropical climatic zones.7–11 In spite of the work alreadydone regarding anilofos environmental fate and persistence,data concerning residues in edible commodities after using theherbicide in the field are still missing. Nevertheless, risk assessmentrelated to pesticide exposure through diet is a main concern andmust therefore be considered.

Data on residues in plants from field trials are sparse. Thepresent study reports on anilofos dissipation kinetics in soil and onresidues in rice plants at harvest from a field trial carried out undersubtropical subhumid conditions in the fields of N.E Borlaug CropResearch Centre (Pantnagar) in the Tarai region of Uttarakhand,India.

∗ Correspondence to: Shishir Tandon, Division of Agricultural Chemicals,Department of Chemistry, College of Basic Sciences and Humanities, G.B. PantUniversity of Agriculture and Technology, Pantnagar-263 145, Uttarakhand,India. E-mail: shishir_tandon@lycos.com; shishir_tandon2000@yahoo.co.in

Division of Agricultural Chemicals, Department of Chemistry, College of BasicSciences and Humanities, G.B. Pant University of Agriculture and Technology,Pantnagar, Uttarakhand, India

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2 MATERIALS AND METHODS2.1 Instruments, chemicals and glasswareThe instruments used in this study were a Water’s high-performance liquid chromatograph (HPLC) and a PC-controlled,double-beam, Systronics UV-vis spectrophotometer (model 2101).

All solvents used in this study were of analytical or HPLC grade.Triple-distilled water was prepared by using a quartz distillationunit. Analytical-grade anilofos (99.4% pure) and its formulation(Anilogaurd 30 EC) were obtained by courtesy of M/s GhardaChemicals Ltd, India. All glassware used in the present study wasof Borosil and Corning make.

2.2 Determination of λmax

A 10 µg mL−1 solution of anilofos (analytical grade) was scannedusing acetonitrile as reference in a UV-vis spectrophotometer fordetermination of λmax. The instrument was operated under thefollowing conditions: bandwidth 0.5 mm, range 200–400 mm,mode scan, scan speed slow.

2.3 TreatmentsField trials on transplanted rice (var. Sarju-52) were conductedduring the rainy season of 2011 at the N.E. Borlaug Crop ResearchCentre, G.B. Pant University of Agriculture and Technology,Pantnagar, India. The distance from plant to plant and from row torow was 10 and 20 cm respectively. Three treatments consistingof control and anilofos were applied as pre-emergent herbicideat 400 and 800 g AI ha−1 respectively. The size of experimentalplots was 10 × 10 m. The experiment was set out in a randomisedblock design (RBD) fashion, and all the treatments were replicated3 times. For field application, quantities of 13.3 mL (0.4 kg AI ha−1)and 26.6 mL (0.8 kg AI ha−1) of anilofos formulation (Aniloguard30EC) were measured and dissolved in 10.0 L of water (equivalentto 1000 L ha−1) and sprayed per plot. The control plot was sprayedwith 10.0 L of water on the same date. All applications weremade with a knapsack sprayer fitted with a 1.2 m long spray boomfitted with three flat-fan spray nozzles.

2.4 SamplingSoil samples (1.0 kg) at a depth of 0–30 cm were collected fromfive randomly selected spots with the help of a tube auger. Thesoil was pooled, air dried and passed through a 2 mm sieve beforefurther processing. Soil samples were collected from all the plotsat different time intervals, i.e. 0 (1 h), 1, 3, 5, 7, 15, 30, 45, 60,75 and 90 days after herbicide application, and finally on theharvesting day (135 DAT). Rice (grain) (0.5 kg), husk (0.25 kg) andstraw samples (0.5 kg) were collected from all plots, i.e. controland treated (at two application rates) at harvest time. Grains ofrice were removed from the husk and were crushed using pestleand mortar, while straw was chopped into small pieces using aNi-coated knife in a machine blender. Subsamples were drawnrandomly using a quartering technique and kept in airtight bagswhich were stored in a deep freeze (−20 ◦C) until extraction.Soil was analysed for pH, cation exchange capacity (CEC), organiccarbon, CaCO3 percentage and proportion of sand silt and clayfraction by standard analytical procedures.12

2.5 Weather conditionsThe meteorological data, comprising temperature, relativehumidity, precipitation and pan evaporation from first spray tofinal sampling (7 June to 20 October), are presented in Table 1.

2.6 Extraction from soil, rice grain, husk and strawAnilofos was extracted from soil (25 g) with 100 mL ofchloroform:acetone solution in 2:1 (v/v) ratio, shaken on ahorizontal shaker for 1 h and centrifuged for 15 min at 3000rpm. The supernatant was filtered through Whatmann filter paper,and soil was re-extracted with 50 + 50 mL of chloroform:acetonesolution (2:1 v/v) mixture. The extracts were combined andconcentrated to dryness under reduced pressure at 45 ± 1 ◦C. Theresidue was dissolved in 50 mL of dichloromethane, partitionedwith an equal volume of dichloromethane:water system in aseparating funnel, shaken vigorously and allowed to separate intotwo layers. The organic layer was collected and the aqueous layerwas again re-extracted twice with 25 mL of dichloromethane.The dichloromethane layer was pooled and dried over anhydroussodium sulfate to remove traces of water. The dichloromethanefraction was filtered and evaporated to dryness under reducedpressure at 30 ± 1 ◦C. The residue was redissolved in 1 mL ofacetonitrile for HPLC analysis. Prior to injection of the sample intothe HPLC, it was filtered through a 0.22 µm Millipore PTFE filter.

Crushed pulverised grains (20 g), rice husk (10 g) and straw (10g) were extracted with 100 mL of chloroform:acetone (2:1 v/v)mixture, shaken on a horizontal shaker for 45 min and centrifugedat 3000 rpm for 15 min. The same procedure was repeated twicewith 50 mL of solvent mixture. The solvent mixture was pooled,dried over sodium sulfate and concentrated to 1 mL and subjectedto clean-up with silica solid-phase extraction. The column wasprewashed with acetone followed by chloroform or n-hexane andeluted with 2 mL chloroform:acetone (1:1 v/v) for grain and n-hexane:acetone (2:1 v/v) for husk and straw. The eluted samplewas dried under a nitrogen stream, and the residue was redissolvedin HPLC-grade acetonitrile (1 mL) and filtered through a 0.22 µmMillipore filter before being subjected to HPLC for analysis.

2.7 Chromatographic conditionsAnalysis of anilofos was done on a Water’s HPLC system with avariable-wavelength UV detector, a C-18 HPLC column (250 × 4.6mm i.d.×5.0µm particle size). The column was maintained at roomtemperature (28 ± 2 ◦C). The mobile phase was acetonitrile:water(85:15 v/v), with a flow rate of 1.0 mL min−1, in isocratic mode.The column eluant was monitored at a wavelength of 229 nm. Thesample was injected in a full-loop volume of 20 µL. The mobilephase was degassed and filtered through a 0.45 µm PTFE disc filterprior to use.

2.8 Calibration curveA stock solution of 50 µg mL−1 of anilofos was prepared bydissolving 0.5 mg in 10 mL of acetonitrile. Serial dilutions ofvarying concentration in the range 0.1–5.0µg mL−1 were preparedby further dilution with acetonitrile. The linearity of the HPLCdetector and calibration curve was evaluated in triplicate atfive concentrations. A 20 µL volume of each concentration wasinjected into the HPLC system, and the peak area obtained foreach concentration was recorded. The measured concentrationsof anilofos in study samples were calculated from the calibrationcurve. The mean values of three replicates were determined foreach sample type.

2.9 Laboratory procedural recovery experimentsFor recovery of anilofos, 200 g of air-dried soil (2 mm sieved),pulverised grain (100 g), rice straw (50 g) and rice husk (50 g) wasplaced in a glass tray and spiked with 0.1, 0.5, 1.0 and 5.0 µg g−1 of

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Table 1. Meteorological dataaduring the experimental period

Temperature (◦C) Relative humidity (%)

Month Week Max. Min. Max. Min. Rainfall (mm) Pan evaporation (mm day−1)

June 2011 1 35.6 23.3 75 52 168 7.3

2 32.9 23.8 77 60 26.8 5.4

3 34.5 25.6 82 61 60.0 5.4

4 31.8 24.9 90 78 240.8 4.7

July 2011 1 33.0 26.1 86 70 3.8 4.2

2 32.8 25.5 89 64 251.6 3.3

3 31.8 24.8 88 71 121.8 3.7

4 31.2 25.5 89 77 193.2 3.2

5 32.1 25.5 91 70 212.8 4.1

August 2011 1 32.6 25.8 87 71 38.6 4.4

2 29.0 24.5 93 85 470.2 5.5

3 32.0 24.9 91 70 99.6 4.3

4 34.6 25.9 83 58 30.2 4.6

September 2011 1 32.2 24.7 87 74 134.0 3.4

2 32.5 24.4 91 68 103.6 3.9

3 31.9 23.2 91 66 0.0 3.4

4 31.2 22.2 92 67 3.8 2.9

October 2011 1 31.8 21.4 92 63 0.0 2.8

2 32.9 19.4 90 57 0.0 3.0

3 31.7 15.9 90 58 0.0 3.2

a Latitude: 29◦ N; longitude: 79◦ 30′ E, altitude: 243.84 m above mean sea level.

analytical-grade anilofos herbicide. All the experiments were donein triplicate. The soil, rice grain, husk and straw were extracted,cleaned up and analysed by the procedure given above in sections2.6 and 2.7.

2.10 Statistical analysisThe experiment was set out in a completely randomised blockdesign fashion, and all the treatments were replicated 3 times. Datawere subjected to statistical analysis to determine the standarddeviation among the replicates.13

3 RESULTS AND DISCUSSIONThe physicochemical properties of the experimental field soilcollected showed that its texture was of the clay loam type, witha slightly alkaline pH and rich in organic carbon (Table 2). Theabsorption maxima for anilofos were found to be at 229 nm.The HPLC retention time of anilofos under optimised operatingconditions was 3.5 min. Clean-up was very efficient in removingcoextractants, and the chromatograms showed no interferingpeak at the retention time of the anilofos. The analytical methodwas validated in terms of limit of quantitation, linearity, precisionand recovery. The recovery of anilofos from spiked samples ofsoil, husk, grain and straw samples was 87.1–94.8, 88.4–91.7,86.3–94.3 and 83.1–91.5% respectively (Table 3). There was nointerfering peak at the retention time for anilofos, indicating goodspecificity of the method. The standard deviation associated withthe determinations ranged from 2.5 to 5.3%. Moreover, the limitof detection of the instrument (3 times the baseline noise) foranilofos was 0.003 µg mL−1, and the limit of quantification of themethod (10 times the baseline noise) for soil, straw, grain andhusk was 0.007, 0.010, 0.008 and 0.010 µg g−1 respectively. Theevaluation of linearity of the HPLC assay was done in triplicate at

Table 2. General physicochemical properties of soil

No. Properties Soil samples (0–30 cm)

1 Sand (%) 45

2 Silt (%) 23

3 Clay (%) 32

4 Texture Clay loam

5 Taxonomic type Mollisol

6 Organic carbon (%) 1.55

7 pH 8.16

8 Electric conductivity (1:2 dS m−1) 0.270

9 CaCO3 (%) 0.464

five concentration levels, i.e. 0.1, 0.5, 1.0, 2.0 and 5.0 µg mL−1 ofanilofos. Detector response was linear to the concentration, as thevalue of the coefficient of determination (R2) was 0.95, showinggood accuracy of the method, with a standard deviation of 2.22%,which is acceptable.

The amount of anilofos recovered from soil for both applicationrates at different time intervals fitted the first-order kineticequation

C = C0 e−λt

where C is the amount of anilofos recovered from soil at time t,C0 is the amount of anilofos recovered at t = 0 interval, λ is thedegradation constant and t is time in days.

For both rates of anilofos application (0.4 and 0.8 kg AI ha−1),the natural logarithm of anilofos residues was plotted againsttime (Figs 1 and 2). The distribution of points for soil at bothlevels of treatment suggested that the dissipation of anilofos mayoccur through a single phase, conforming to first-order kinetics.

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Table 3. Percentage recovery of anilofos from fortified samples ofstraw, grain, husk and soila

Samples Amount loaded (µg g−1) Percentage recovery

Straw 0.1 83.05 ± 0.05

0.5 86.45 ± 0.15

1.0 88.18 ± 0.02

5.0 91.50 ± 0.14

Grain 0.1 86.26 ± 0.03

0.5 88.90 ± 0.1

1.0 90.45 ± 0.09

5.0 94.3 ± 0.15

Soil 0.1 87.10 ± 0.09

0.5 90.50 ± 0.05

1.0 91.50 ± 0.10

5.0 94.76 ± 0.11

Husk 0.1 88.42 ± 0.07

0.5 89.20 ± 0.12

1.0 89.95 ± 0.08

5.0 91.66 ± 0.15

a Average of three replicates.

Figure 1. Plots of natural logarithm of anilofos concentration in soil versustime at 0.4 kg ha−1.

Figure 2. Plots of natural logarithm of anilofos concentration in soil versustime at 0.8 kg ha−1.

The computed values of R2 between ln residues in soil and timevaried from 0.9860 to 0.9778 (significant at P = 0.05), indicatingthat the dissipation of anilofos could be accounted for by first-order kinetics. The half-life values of anilofos in different sampleswere calculated from the slope of the regression equation. In soil,the computed half-life values of anilofos were 12.9 and 15.5 daysfor the lower rate of application (0.4 kg AI ha−1) and the higherrate of application (0.8 kg AI ha−1) respectively (Table 4).

Table 4. Kinetic values of degradation rate constant, half-life andcoefficient of determination of anilofos in soil

Anilofos

Computed value 0.4 kg ha−1 0.8 kg ha−1

Degradation rateconstant λ

0.06 0.05

Half-life T1/2 (days) 13 15

Coefficient ofdetermination R2

0.98 0.97

Regressionequation

y = −0.0278x − 0.4759 y = −0.0141x − 0.1655

Table 5. Persistence of anilofos in rice soil under field condition

Amount of anilofos

recovereda (µg g−1)

Incubation interval 0.4 kg ha−1 0.8 kg ha−1

0 days 0.36 ± 0.06 0.75 ± 0.10

1 day 0.34 ± 0.07 0.69 ± 0.09

3 days 0.31± 0.05 0.60 ± 0.09

5 days 0.25 ± 0.04 0.54 ± 0.07

7 days 0.17 ± 0.05 0.50 ± 0.05

15 days 0.11 ± 0.03 0.43 ± 0.04

30 days 0.05 ± 0.01 0.31 ± 0.05

45 days 0.02 ± 0.005 0.18 ± 0.03

60 days BDLb 0.11 ± 0.02

75 days BDL 0.05 ± 0.006

90 days BDL BDL

Harvest day BDL BDL

a Mean value of three replicates.b BDL = below detectable limit (limit of quantitation <0.007 µg g-1).

The percentage dissipation values at different time intervalswere calculated with the amount of herbicide recovered on dayzero (1 h after application) considered to be 100%. The valuesobtained for persistence as well as dissipation at 400 and 800 ganilofos ha−1 are depicted in Table 5.

According to Zhang et al.,14 with increase in temperature from20 to 40 ◦C, degradation increased from 10.4 to 37.6%, variationin soil water content increased from 45.0 to 68.4%, and thedegradation rate varied from 30 to 110%. With decrease in theorganic matter content from 3.35 to 0.55%, the half-life of anilofosincreased from 11 to 15 days and the half-life in terms of alterationof pH from acidic (6.01) to alkaline (7.98) for anilofos decreasedfrom 22 to 15 days; thus, organic matter, water content andtemperature of soil enhanced anilofos degradation, while thedegradation rate of the chemical was higher in alkaline soil thanin acid soil. In Yangzhou soil of China, degradation of anilofosin rice was rapid, and its half-life was 1–2, 2–3 and 4–5 daysfor water, plant and soil respectively; after the growing season,residue of anilofos in both rice and soil was not detectable.15

In three different Chinese soils, namely clay, loam and sandy,the half-life of anilofos varied from 64.2 to 161.2 days.16 Intop soil of the coastal region, anilofos persisted for a longerduration in inceptisol than in alfisol soil. Degradation followedfirst-order kinetics, and the half-life varied from 3.2 to 3.7 daysand from 3.9 to 4.6 days in alfisol and inceptisol respectively.11,17

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Under laboratory conditions, degradation of anilofos was studiedin six types of soil. Degradation followed a first-order reactionirrespective of the soil and water regimes. Degradation of anilofosherbicide in soils was more rapid under flooded than under non-flooded conditions; the half-life of anilofos under non-floodedand flooded conditions was 13.9–30.1 days and 5.4–23.2 daysrespectively.9

At harvest time in the present study, anilofos residue analysiswas done in soil, rice grain, husk and straw, and no detectableamount of anilofos residue was observed at either application rate.The absence of anilofos residues in plant parts at the harvestingstage might be due to the plant’s enzymatic actions on anilofosor to the formation of conjugates. Balasubramanian et al.18 alsoreported that, when anilofos was applied at the recommendedrate continuously for four seasons in rice, residues in soil and plantparts were lower than the maximum residue level (MRL).

Limited data on the fate of anilofos in soil and plant are availablein the literature. Hydrolytic cleavage of the P–S alkyl is the primarydegradation/metabolism of anilofos in soil, plant and animal.19

Fast degradation of anilofos under field conditions would beattributed to the hot and humid Indian climatic conditions and theflooded/anaerobic conditions prevalent during the crop season.During the experimental period, the temperature ranged from 16to 36 ◦C and relative humidity from 52 to 92%. High temperatureand flooded conditions play an important role and favour rapiddegradation of the herbicide. The soil of the experimental plotwas rich in organic carbon and had an alkaline pH, and thesefactors also had an influence on the enhanced degradation ofthe pesticide. Under these field conditions, residues of anilofoswere completely lost from harvest soil and were below detectablelevels.

4 CONCLUSIONThe dissipation study on anilofos revealed that it undergoesrapid dissipation and has first-order degradation kinetics insoil, with a half-life of 12.97 days (0.4 kg AI ha−1) and 15.49days (0.8 kg AI ha−1), whereas in husk, grain and straw, atthe time of harvesting, anilofos below the detectable amountwas observed under subhumid and subtropical conditions oftransplanted rice. Analysis of harvest samples of soil, rice strawand grain indicated that samples were free from anilofos herbicideresidues, indicating that anilofos is a safe herbicide for weedcontrol in rice crop. Exposure to anilofos pesticide throughfood is safe and meets the rigorous human health standards.This assessment showed that the levels of anilofos to whichhumans/animals are exposed in their food/crop are safe forconsumption as they are below the MRL values (0.01 ppm, JapanFood Chemical Research Foundation) that would potentially causehealth effects.

ACKNOWLEDGEMENTThe author is grateful to M/s Gharda Chemical Ltd, India, forproviding the analytical grade and formulation (Aniloguard 30EC)of anilofos for research purposes.

REFERENCES1 Mishra B, Rice in India. Crop-report-rice. Agrolook 3:4–22 (2002).2 Rice Knowledge Management Portal. [Online]. Weed Information System

(WISY) (2011). Available: http://www.wisy.rkmp.co.in/ [15 February2013].

3 Tosh GC and Jena HC, Weed control in dry seeded lowland rice withbentazone combined with 2,4-D. IRRN 9:19 (1984).

4 Annual Report for 1996. International Rice Research Institute, Manila,Philippines (1997).

5 Singh S, Singh G, Singh VP and Singh AP, Effect of establishmentmethods and weed management practices on weeds and rice inrice–wheat cropping system. Ind J Weed Sci 37:51–57 (2005).

6 Tomlin CDS, The Pesticide Manual, 13th edition. British Crop ProtectionCouncil, Farnham, Surrey, UK (2003).

7 Dhawan RS and Malik RK, Persistence of anilofos in soil. Ind J Weed Sci25(3/4):108–109 (1993).

8 Rai AK, Chhonkar PK and Agnihotri NP, Persistence of pendimethalinand anilofos in six diverse soils. Pestic Res J 11(2):132–137 (1999).

9 Rai AK, Chhonkar PK and Agnihotri NP, Persistence and degradationof pendimethalin and anilofos in flooded versus non-flooded soils.J Indian Soc Soil Sci 48(1):57–62 (2000).

10 Zhang Li, Wen Han Ni, Lin LiS, Fan QC, Dan Liu and Jun HJi, Study onresidues of anilofos in rice plant grain soil and water. Agrochemicals2000(1):25–26 (2000).

11 Maheswari ST and Ramesh A, Adsorption and degradation of anilofosin different soils and its environmental impact in soils. Int J EnvironRes 6(2):451–456 (2012).

12 Jackson ML, Soil Chemical Analysis. Prentice Hall India Pvt. Ltd, NewDelhi, India, 929 pp. (1973).

13 Gomez KA and Gomez AA, Statistical Procedure for Agricultural Research.John Wiley & Sons, New York, NY, 680 pp. (1984).

14 Zhang Li, Wen HanNi, Wen ZhangJi and Lin LiShan, Effect ofenvironmental conditions on degradation of anilofos in soil. Chin JPestic Sci 2000(3):74–79 (2000).

15 Han LiJ, Liu D, Fan ZJ, Qian, CF, Jiang SR, Zhang Li et al., Degradation ofanilofos in paddy soil and its residue in rice plant. J Chin Agric Univ5(1):112–116 (2000).

16 Liu Y, Tang F and Zhu G, The environmental risk assessment ofherbicide anilofos on various Chinese cultivated soils. Adv Mater Res356–360:1786–1789 (2012).

17 Ramesh A and Maheswari ST, Dissipation of Anilofos in TwoDifferent Soils (Alfisol and Inceptisol) under Predominant CroppingConditions (Paddy) – Bio Accumulation of Residues in Fish.[Online]. (2008). Available: http://www.amazines.com/Science_and_Technology/article_detail.cfm/724632?articleid=724632 [15February 2013].

18 Balasubramanian R, Veerabadran V and Kannathasan M, Influenceof continuous use of herbicides in rice based system on residueaccumulation and on performance of succeeding pulse crop. PesticRes J 11(2):200–203 (1999).

19 Roberts TR and Hutson DH, Metabolic Pathways of Agrochemicals. PartI: Herbicides and Plant Growth Regulators. Royal Society of Chemistry,Cambridge, UK, pp. 387–389 (1998).

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