Environ Monit Assess (2015) 187:221 DOI 10.1007/s10661-015-4451-4
Harvest time residues of pendimethalin and oxyfluorfen in vegetables and soil in sugarcane-based intercropping systems Navneet Kaur & Makhan S. Bhullar
Received: 10 October 2014 / Accepted: 18 March 2015 # Springer International Publishing Switzerland 2015
Abstract Terminal residues of pendimethalin and oxyfluorfen applied in autumn sugarcane- and vegetables-based intercropping systems were analyzed in peas (Pisum sativum), cabbage (Brassica oleracea), garlic (Allium sativum), gobhi sarson (Brassica napus), and raya (Brassica juncea). The study was conducted in winter season in 2010–2011 and in 2011–2012 at Ludhiana, India. Pendimethalin at 0.56 kg and 0.75 kg ha−1 was applied immediately after sowing of gobhi sarson, raya, peas, garlic, and 2 days before transplanting of cabbage seedlings. Oxyfluorfen at 0.17 kg and 0.23 kg ha−1 was applied immediately after sowing of peas and garlic and 2 days before transplanting of cabbage seedlings intercropped in autumn sugarcane. Representative samples of these vegetables were collected at 75, 90, 100, and 165 days after application of herbicides and analyzed by highperformance liquid chromatograph (HPLC) with diode array detector for residues. The residue level of pendimethalin and oxyfluorfen in mature vegetables was found to be below the limit of quantification which is 0.05 mg kg−1 for both the herbicides. The soil samples were collected at 0, 7, 15, 30, 45, and 60 days after the application of their herbicides. The residues of herbicides in soil samples were found to be below the detectability limit of 0.05 mg kg−1 after 60 days in case of pendimethalin and after 45 days in case of oxyfluorfen. N. Kaur (*) : M. S. Bhullar Punjab Agricultural University, Ludhiana 141004 Punjab, India e-mail: [email protected]
Keywords HPLC . Pendimethalin . Oxyfluorfen . Residues
Introduction Sugarcane is an important commercial crop of the world and more than 100 countries produce sugar, 78 % of that is made from sugarcane. Brazil, Cuba, Mexico, India, and Thailand are leading producers of cane sugar. India ranks second among sugarcane growing countries in terms of both area and production, after Brazil. Sugar industry is the second largest agro-industry in India. More than 50 million farmer families, constituting 7.5 % of the rural population, are involved in sugarcane cultivation, harvesting, and ancillary activities; many workers are employed indirectly in processing (Dharni et al. 2007). India harvested 350 million tons of sugarcane from 5.03 million hectares during 2014–2015 (www.indiastat.com). Autumn sugarcane gives 15–20 % higher cane yield and 0.5 unit more sugar recovery than spring-planted sugarcane (Singh et al. 2008). Many short-duration crops including cabbage, potato, onion, wheat, raya, gobhi sarson, peas, toria, and radish have been recommended for intercropping in autumn sugarcane (Lal and Singh. 2004; Anonymous 2012). The intercropping systems of autumn sugarcane with wheat, raya, mustard, peas, and cabbage gave significantly higher caneequivalent yield, net profit, and better juice quality than sole sugarcane (Mathur et al. 1968; Misra 1964).
221
Page 2 of 6
The weed problem is more acute in sugarcane being a long-duration crop with slow initial growth habit. Weeds growing in furrows along the sugarcane row have been found to be more harmful than the weeds growing on ridges between the two rows (Sathyavelu and Somasundaram 2002). Cane yield losses due to the presence of weeds were estimated to the tune of 12 to 83 % (Shafi Nazir et al. 2002; Hunsingi 1993; Kanwar et al. 1992). However, these losses depend upon the weed intensity and stages of infestation besides the stage of crop. Removing weeds at any time during growing season may not be beneficial. A weedfree environment during the germination stage and tillering phase is important for getting higher productivity (Ponnusamy et al. 1996). However, hand weeding and interculture in between the rows is labor intensive, costly, and less efficient. Sometimes, the non availability of labor during peak season and wet field conditions at the critical period of crop-weed competition do not permit the removal of weeds by mechanical means. This discourages the farmers to adopt intercropping in sugarcane. These problems necessitated the use of herbicides for timely and effective control of weeds as well as to economize the costly labor (Bhullar et al. 2006). Herbicide residue estimation in soil and edible plant parts is very essential to determine the duration of herbicide activity in soil and its effect on the crops and to analyze the quality of the food. Present study was undertaken to observe the extent of persistence of pendimethalin and oxyfluorfen residues in gobhi sarson, raya, cabbage, peas, and garlic raised as intercrops in autumn sugarcane.
Materials and methods Chemicals and reagent Oxyfluorfen reference analytical standard was obtained from Dr. Ehrenstorfer GmbH, Germany. Pendimethalin reference analytical standard of 99.9 % purity was obtained from ACCU standard, USA. Acetonitrile, methanol, dichloromethane, anhydrous sodium sulfate, and sodium chloride of analytical grade were procured from were analytical grade reagent (E Merck).
Environ Monit Assess (2015) 187:221
Application of pendimethalin and oxyfluorfen The field experiment was conducted during winter season in 2010–2011 and in 2011–2012 at research farm of Department of Agronomy, Punjab Agricultural University (PAU), Ludhiana, India. Pendimethalin was applied at 0.56 and 0.75 kg ha−1 to gobhi sarson (Brassica napus), raya (Brassica juncea), cabbage, peas, garlic, and oxyfluorfen at 0.17 and 0.23 kg ha−1 to cabbage (Brassica oleracea), peas (Pisum sativum), and garlic (Allium sativum) intercropped with autumn sugarcane. The herbicides were applied immediately after sowing in case of gobhi sarson, raya, peas, and garlic, and 2 days before transplanting of cabbage seedlings. The experimental soil was loamy sand with 78.2 % sand, 13.1 % silt, 8.4 % clay, and 0.36 % organic carbon having pH 7.2. Total rainfalls received during intercrop season were 82.5 and 65.4 mm in first and second year, respectively. The sugarcane variety CoJ 85 was sown in rows spaced at 90 cm. One row of gobhi sarson and cabbage, two rows of raya and peas, and three rows of garlic were intercropped in between two rows of sugarcane. The herbicides were sprayed as pre emergence using a spray volume of 500 l ha−1 with a knapsack sprayer fitted with flat fan nozzle. The residue analysis of herbicides viz. pendimethalin and oxyfluorfen was done at the time of harvest of intercrops viz. gobhi sarson, raya, cabbage, peas, and garlic. Samples of gobhi sarson, raya, cabbage, peas, garlic, and soil were collected from the experimental plots. Vegetable was chopped using a chopper and blended properly using a high-speed blender. Green leaves of gobhi sarson and raya, small pieces of cabbage, crushed seeds of peas and cloves of garlic were taken for residue analysis. From that aliquot representative samples of 25 g were taken. The samples were extracted for the herbicides as per the methods given by Sondhia and Dubey (2006) and analyzed on a Waters 2489 High Performance Liquid Chromatography system equipped with 515 HPLC pump and UV-Visible detector. For extraction of residues, samples were dipped in acetone for overnight. Mixture was filtered with filter paper (Whatman No. 1), and the residue rinsed thrice with 50 ml of acetone. The extract was transferred into a 500 ml separatory funnel with 100 ml of aqueous NaCl solution (50 g l−1) and extracted with 100 ml of dichloromethane. Organic layers were collected by passing through
Environ Monit Assess (2015) 187:221
Page 3 of 6 221
anhydrous sodium sulfate. The aqueous layer was further partitioned with 50 ml dichloromethane. The dichloromethane extract was concentrated to near dryness, and then re-dissolved in 5 ml acetonitrile and cleaned up with a florisil column. Elusion of the column was done with dichloromethane and acetone in 2:1 ratio. The column elute was concentrated and redissolved in 5 ml acetonitrile for HPLC analysis. Similar methodology was followed for the soil samples. Analysis of the pendimethalin and oxyfluorfen residues were carried out using high performance liquid chromatograph equipped with Photodiode detector. A Phenomenox-C18 Column (250×4.6 mm) was used for their estimation. Mobile phase was acetonitrile with a flow rate of 0.5 ml min−1. Detector wave length for pendimethalin and oxyfluorfen was 240 and 205 nm, respectively. The presence of pendimethalin and oxyfluorfen in the samples was identified and quantified by comparison of the retention time and peak heights of the sample chromatograms with that of the standard run under identical operating conditions. Under these operating conditions, the retention time for pendimethalin and oxyfluorfen was 3.5 and 2.92 min, respectively.
Detection limit for both the compound was 0.05 ppm.
Results and discussion In the present investigation, recovery experiments were carried out at different levels to establish the reliability and validity of analytical method and to know the efficiency of extraction and cleanup procedures. To judge the efficacies of extraction and cleanup, the recovery experiments were performed. Samples of gobhi sarson, raya, cabbage, peas, garlic, and soil from control plots were spiked at levels of 0.20, 0.10, and 0.05 mg kg−1. These were extracted, cleaned, and analyzed following the method already described. The control samples from untreated plots and reagent blanks were also processed in the same way so as to find out the interferences, if any, due to the substrate and reagents, respectively. The mean percent recoveries of pendimethalin and oxyfluorfen from samples at the fortification level of 0.20 to 0.05 mg kg−1 ranged from 86 to 98 (Table 1). The average
Table 1 Recovery studies of pendimethalin and oxyfluorfen on gobhi sarson, raya, cabbage, peas, garlic, and soil (n=6) Substrates
Level of fortification (mg kg−1)
Pendimethalin Mean recovery (%)
Gobhi sarson
Raya
Cabbage
Peas
Garlic
Soil
Oxyfluorfen RSD r (%)
Mean recovery (%)
RSD r (%)
0.20
95.60
1.24
95.80
1.43
0.10
92.00
1.85
92.78
3.75
0.05
87.88
1.93
85.29
0.74
0.20
98.00
4.39
90.43
1.39
0.10
95.50
3.28
89.27
2.56
0.05
86.49
4.15
87.73
5.51
0.20
93.77
3.72
92.51
5.15
0.10
95.00
1.82
88.13
2.58
0.05
88.50
0.63
88.02
1.43
0.20
92.72
5.20
89.37
4.47
0.10
89.06
2.68
84.63
1.95
0.05
86.52
2.29
83.72
3.20
0.20
93.37
5.31
87.32
4.28
0.10
90.31
2.58
89.63
1.84
0.05
86.69
4.99
86.64
4.49
0.20
95.03
3.38
92.20
2.86
0.10
94.20
2.37
91.25
3.80
0.05
88.10
1.61
86.17
2.47
221
Environ Monit Assess (2015) 187:221
Page 4 of 6 700000
Area observed (milivolt-sec)
Fig. 1 Standard curve for pendimethalin
Area
600000 500000
y = 1E+06x - 69273 R² = 0.9956
400000 300000 200000 100000 0
0
0.1
Area observed (milivolt-sec)
recovery values were found to be more than 85 %; thus, the results have been presented as such without applying any correction factor. The calibration curve for pendimethalin was prepared by injecting different known concentrations (0.1, 0.2, 0.3, 0.4, and 0.5 ppm) of the compound. The calibration details have been presented in Table 1. A calibration curve has been plotted (Figs. 1 and 2) for the concentration of the standards injected versus the peak area observed, and the curve was found to be linear up to the lowest concentration range of 0.1 ppm. The approximate retention time was obtained at 3.5 min. Immediately after 2 h (0 day) of treatment, the average pendimethalin residue in the soil at 0– 20 cm depth was found 0.46 mg kg−1 at 0.56 kg ha−1 dose indicating that pendimethalin was evenly distributed on field surface (Table 2). With passage of time, pendimethalin residues decreased successively and reached the level of 0.26 and 0.11 mg kg−1
Fig. 2 Standard curve for oxyfluorfen
Linear (Area)
0.2
0.3 0.4 Concentration(ng)
0.5
0.6
after 7 and 15 days in 0.56 kg ha−1 treatment, respectively. Dissipation of pendimethalin was continued with time and by 45 was found to be 0.05 in 0.56 kg ha−1 treatment. However, 0.65, 0.45, 0.15, and 0.09 mg kg−1 pendimethalin residues were detected in soil at 0, 7, 15, and 30 days after application at 0.75 kg ha −1 . Pendimethalin residues were found to be below the limit of quantification after 60 days of application. Oxyfluorfen residue in the soil was studied after 0, 7, 15, 30, 45, and 60 days interval when oxyfluorfen was applied in soil at 0.17 and 0.23 kg ha−1 pre emergence. Initially, when the soil samples were taken after 2 h of spray, the residues of oxyfluorfen were found to be 0.16 and 0.21 mg kg−1 when applied at 0.17 and 0.23 kg ha−1, respectively (Table 3). The residues of oxyfluorfen were degraded gradually and reached the level of below detectability limit after 45 days in both the treatments.
1600000 1400000
Area
1200000
Linear (Area) y = 272682x + 75691 R² = 0.9947
1000000 800000 600000 400000 200000 0
0
1
2
3
Concentration (ng)
4
5
6
Environ Monit Assess (2015) 187:221
Page 5 of 6 221
Table 2 Residues of pendimethalin (mg kg−1) in the soil Sampling time (days)
at 0.56 kg ha−1
at 0.75 kg ha−1 0.65±0.05
0
a
7
0.26±0.05
0.45±0.03
15
0.11±0.06
0.15±0.02
30
0.07±0.05
0.09±0.01
45
0.05±0.04
0.06±0.01
60
BDL
BDL
a
0.46±0.049
Mean ± SD of three replications
Table 4 Residue of pendimethalin (mg kg −1 ) studied in vegetables Sampling time at 0.56 kg ha−1 at 0.75 kg ha−1 (at harvest) 2010–2011 2011–2012 2010–2011 2011–2012
75 DAS 90 DAS 90 DAS
BDL Below detectability limit; 0.05 ppm 100 DAS
The results were in accordance with the Sondhia and Dubey (2006) and Sondhia (2007). They observed that when pendimethalin applied at 0.75 kg a.i. ha−1 was found to be 0.47, 0.05, 0.04, and 0.02 μg g−1 after 15, 30, 60, and 90 days in the soil samples, respectively. Pendimethalin is known for its high adsorption onto the soil and organic matter. Pendimethalin adsorbs strongly to topsoil, and soil–water partition coefficients (Kd values) ranging from 99.8 (0.59 % organic carbon) to 1638 (16.9 % organic carbon) have been reported (Zheng and Cooper 1996). In spite of high adsorption of pendimethalin to soil, several reports indicated long persistence of pendimethalin. Jaźwa et al. (2009) reported half-lives of pendimethalin 60–62 days in the soil of fennel field. Raj et al. (1999) reported that organic matter content of the soil was responsible for high adsorption of pendimethalin. The analysis of gobhi sarson, raya, cabbage, peas, and garlic samples indicated that despite the presence of
Table 3 Residues of oxyfluorfen (mg kg−1) in the soil Sampling time (days)
at 0.17 kg ha−1
0
0.16±0.03
0.21±0.02
7
0.11±0.02
0.13±0.01
15
0.08±0.01
0.10±0.02
30
0.05±0.02
0.08±0.01
45
BDL
BDL
60
BDL
BDL
a
Mean ± SD of three replications
BDL Below detectability limit; 0.05 ppm
at 0.23 kg ha−1
165 DAS
Cabbage BDL BDL Gobhi sarson BDL BDL Raya BDL BDL Peas BDL BDL Garlic BDL BDL
BDL
BDL
BDL
BDL
BDL
BDL
BDL
BDL
BDL
BDL
BDL Below detectability limit; 0.05 ppm
high level of pendimethalin residues in soil surface, the residues of pendimethalin at 0.56 and 0.75 kg a.i. ha−1 were found to be below the limit of quantification in samples collected at their harvestable stage (Table 4). Similar results were observed in case of oxyfluorfen at both the dosages (Table 5). The herbicides were sprayed at the time of sowing, and the sampling was carried out at harvesting. There was a long time gap between herbicide application and analysis resulting in its degradation. Soil microbes might be one of the factors responsible for degradation of these herbicides. Residues of pendimethalin applied 1 kg ha−1 pre emergence to tomato, cauliflower, and radish crops were below detectability limit at the time of harvest of these vegetables (Sondhia 2013). The study indicated that pendimethalin and oxyfluorfen applied at recommended doses in the
Table 5 Residue of oxyfluorfen (mg kg−1) studied in vegetables Sampling time at 0.17 kg ha−1 at 0.23 kg ha−1 (at harvest) 2010–2011 2011–2012 2010–2011 2011–2012 Cabbage 75 DAS
BDL
BDL
BDL
BDL
BDL
BDL
BDL
BDL
BDL
BDL
Peas 100 DAS
BDL Garlic
165 DAS
BDL
BDL Below detectability limit; 0.05 ppm
221
Page 6 of 6
present trial are safe for use in the gobhi sarson, raya, cabbage, peas, and garlic. Acknowledgments The authors are thankful to the Heads of Department of Agronomy and Entomology, PAU, Ludhiana for providing the necessary research facilities.
References Anonymous (2012) Package of practices for Kharif crops. Ludhiana: Punjab Agricultural University. Bhullar, M. S., Kamboj, A., & Singh, G. P. (2006). Weed management in spring planted sugarcane (Saccharum officinarum) based intercropping systems. Indian Journal of Agronomy, 51, 183–185. Dharni, K., Singh, R., & Sharma, S. (2007). Sugarcane market scenario. Progressive Farming, 43, 16–27. Hunsingi, G. (1993). Production of sugarcane—Theory and practice (pp. 144–147). Berlin: Springer Ver Lag. Jaźwa, A., Szpyrka, E., & Sadło, S. (2009). Disappearance of pendimethalin in soil and its residue in ripe fennel. Journal Central European Agriculture, 10, 153–158. Kanwar, R. S., Singh, S., Sodhi, R. S., & Garcha, A. I. S. (1992). Comparative performance of different herbicides combination for weed control in sugarcane. Indian Sugar, 42, 621–625. Lal, M., & Singh, A. K. (2004). Technology package for sugarcane based intercropping systems. Lucknow: Indian Institute of Sugarcane Reasearch. Mathur, B. K., Singh, A., & Bhadawire, V. S. (1968). Intercropping in sugarcane. Indian Sugarcane, 13, 1043– 1048.
Environ Monit Assess (2015) 187:221 Misra, G. N. (1964). Mixed cropping effects of certain intercrops on the yield and juice quality of sugarcane. Indian Sugar, 14, 1–17. Ponnusamy, K.P., Santhi, & Sankaran, S. (1996). Effect of herbicides on growth and yield of early sugarcane var. CoC 671. Pestology, 20, 22–26. Raj, M. F., Patel, B. K., & Shah, P. G. (1999). Adsorption and desorption of pendimethalin, fluchloralin and oxadiazon on soils. Pesticide Research Journal, 11, 162–167. Sathyavelu, A., & Somasundaram, E. (2002). Integrated weed management in sugarcane. Indian Sugar, 53, 871–873. Shafi Nazir, M., Abdul, J., Imtiaz, A., Shah, N., & Iftikhar, H. B. (2002). Production potential and economics of intercropping in autumn planted sugarcane. International Journal of Agricultural Biology, 4, 140–142. Singh, A. K., Lal, M., & Archana, S. (2008). Effect of intercropping in sugarcane (Saccharum complex hybrid) on productivity of plant cane—Ratoon system. Indian Journal of Agronomy, 53, 140–144. Sondhia, S. (2007). Evaluation of leaching potential of pendimethalin in clay loam soil. Pesticide Research Journal, 19, 119–121. Sondhia, S. (2013). Harvest time residues of pendimethalin in tomato, cauliflower, and radish under field conditions. Toxicology and Environmental Chemistry, 95, 254–259. Sondhia, S., & Dubey, R. P. (2006). Determination of terminal residues of butachlor and pendimethalin in onion. Pesticide Research Journal, 18, 85–86. www.Indiastat.com visited on March 9, 2015. Zheng, S. Q., & Cooper, J. F. (1996). Adsorption, desorption and degradation of three pesticides in different soils. Archives of Environmental Contamination Toxicology, 30, 15–20.
Harvest time residues of pendimethalin and oxyfluorfen in vegetables and soil in sugarcane-based intercropping systems Navneet Kaur & Makhan S. Bhullar
Received: 10 October 2014 / Accepted: 18 March 2015 # Springer International Publishing Switzerland 2015
Abstract Terminal residues of pendimethalin and oxyfluorfen applied in autumn sugarcane- and vegetables-based intercropping systems were analyzed in peas (Pisum sativum), cabbage (Brassica oleracea), garlic (Allium sativum), gobhi sarson (Brassica napus), and raya (Brassica juncea). The study was conducted in winter season in 2010–2011 and in 2011–2012 at Ludhiana, India. Pendimethalin at 0.56 kg and 0.75 kg ha−1 was applied immediately after sowing of gobhi sarson, raya, peas, garlic, and 2 days before transplanting of cabbage seedlings. Oxyfluorfen at 0.17 kg and 0.23 kg ha−1 was applied immediately after sowing of peas and garlic and 2 days before transplanting of cabbage seedlings intercropped in autumn sugarcane. Representative samples of these vegetables were collected at 75, 90, 100, and 165 days after application of herbicides and analyzed by highperformance liquid chromatograph (HPLC) with diode array detector for residues. The residue level of pendimethalin and oxyfluorfen in mature vegetables was found to be below the limit of quantification which is 0.05 mg kg−1 for both the herbicides. The soil samples were collected at 0, 7, 15, 30, 45, and 60 days after the application of their herbicides. The residues of herbicides in soil samples were found to be below the detectability limit of 0.05 mg kg−1 after 60 days in case of pendimethalin and after 45 days in case of oxyfluorfen. N. Kaur (*) : M. S. Bhullar Punjab Agricultural University, Ludhiana 141004 Punjab, India e-mail: [email protected]
Keywords HPLC . Pendimethalin . Oxyfluorfen . Residues
Introduction Sugarcane is an important commercial crop of the world and more than 100 countries produce sugar, 78 % of that is made from sugarcane. Brazil, Cuba, Mexico, India, and Thailand are leading producers of cane sugar. India ranks second among sugarcane growing countries in terms of both area and production, after Brazil. Sugar industry is the second largest agro-industry in India. More than 50 million farmer families, constituting 7.5 % of the rural population, are involved in sugarcane cultivation, harvesting, and ancillary activities; many workers are employed indirectly in processing (Dharni et al. 2007). India harvested 350 million tons of sugarcane from 5.03 million hectares during 2014–2015 (www.indiastat.com). Autumn sugarcane gives 15–20 % higher cane yield and 0.5 unit more sugar recovery than spring-planted sugarcane (Singh et al. 2008). Many short-duration crops including cabbage, potato, onion, wheat, raya, gobhi sarson, peas, toria, and radish have been recommended for intercropping in autumn sugarcane (Lal and Singh. 2004; Anonymous 2012). The intercropping systems of autumn sugarcane with wheat, raya, mustard, peas, and cabbage gave significantly higher caneequivalent yield, net profit, and better juice quality than sole sugarcane (Mathur et al. 1968; Misra 1964).
221
Page 2 of 6
The weed problem is more acute in sugarcane being a long-duration crop with slow initial growth habit. Weeds growing in furrows along the sugarcane row have been found to be more harmful than the weeds growing on ridges between the two rows (Sathyavelu and Somasundaram 2002). Cane yield losses due to the presence of weeds were estimated to the tune of 12 to 83 % (Shafi Nazir et al. 2002; Hunsingi 1993; Kanwar et al. 1992). However, these losses depend upon the weed intensity and stages of infestation besides the stage of crop. Removing weeds at any time during growing season may not be beneficial. A weedfree environment during the germination stage and tillering phase is important for getting higher productivity (Ponnusamy et al. 1996). However, hand weeding and interculture in between the rows is labor intensive, costly, and less efficient. Sometimes, the non availability of labor during peak season and wet field conditions at the critical period of crop-weed competition do not permit the removal of weeds by mechanical means. This discourages the farmers to adopt intercropping in sugarcane. These problems necessitated the use of herbicides for timely and effective control of weeds as well as to economize the costly labor (Bhullar et al. 2006). Herbicide residue estimation in soil and edible plant parts is very essential to determine the duration of herbicide activity in soil and its effect on the crops and to analyze the quality of the food. Present study was undertaken to observe the extent of persistence of pendimethalin and oxyfluorfen residues in gobhi sarson, raya, cabbage, peas, and garlic raised as intercrops in autumn sugarcane.
Materials and methods Chemicals and reagent Oxyfluorfen reference analytical standard was obtained from Dr. Ehrenstorfer GmbH, Germany. Pendimethalin reference analytical standard of 99.9 % purity was obtained from ACCU standard, USA. Acetonitrile, methanol, dichloromethane, anhydrous sodium sulfate, and sodium chloride of analytical grade were procured from were analytical grade reagent (E Merck).
Environ Monit Assess (2015) 187:221
Application of pendimethalin and oxyfluorfen The field experiment was conducted during winter season in 2010–2011 and in 2011–2012 at research farm of Department of Agronomy, Punjab Agricultural University (PAU), Ludhiana, India. Pendimethalin was applied at 0.56 and 0.75 kg ha−1 to gobhi sarson (Brassica napus), raya (Brassica juncea), cabbage, peas, garlic, and oxyfluorfen at 0.17 and 0.23 kg ha−1 to cabbage (Brassica oleracea), peas (Pisum sativum), and garlic (Allium sativum) intercropped with autumn sugarcane. The herbicides were applied immediately after sowing in case of gobhi sarson, raya, peas, and garlic, and 2 days before transplanting of cabbage seedlings. The experimental soil was loamy sand with 78.2 % sand, 13.1 % silt, 8.4 % clay, and 0.36 % organic carbon having pH 7.2. Total rainfalls received during intercrop season were 82.5 and 65.4 mm in first and second year, respectively. The sugarcane variety CoJ 85 was sown in rows spaced at 90 cm. One row of gobhi sarson and cabbage, two rows of raya and peas, and three rows of garlic were intercropped in between two rows of sugarcane. The herbicides were sprayed as pre emergence using a spray volume of 500 l ha−1 with a knapsack sprayer fitted with flat fan nozzle. The residue analysis of herbicides viz. pendimethalin and oxyfluorfen was done at the time of harvest of intercrops viz. gobhi sarson, raya, cabbage, peas, and garlic. Samples of gobhi sarson, raya, cabbage, peas, garlic, and soil were collected from the experimental plots. Vegetable was chopped using a chopper and blended properly using a high-speed blender. Green leaves of gobhi sarson and raya, small pieces of cabbage, crushed seeds of peas and cloves of garlic were taken for residue analysis. From that aliquot representative samples of 25 g were taken. The samples were extracted for the herbicides as per the methods given by Sondhia and Dubey (2006) and analyzed on a Waters 2489 High Performance Liquid Chromatography system equipped with 515 HPLC pump and UV-Visible detector. For extraction of residues, samples were dipped in acetone for overnight. Mixture was filtered with filter paper (Whatman No. 1), and the residue rinsed thrice with 50 ml of acetone. The extract was transferred into a 500 ml separatory funnel with 100 ml of aqueous NaCl solution (50 g l−1) and extracted with 100 ml of dichloromethane. Organic layers were collected by passing through
Environ Monit Assess (2015) 187:221
Page 3 of 6 221
anhydrous sodium sulfate. The aqueous layer was further partitioned with 50 ml dichloromethane. The dichloromethane extract was concentrated to near dryness, and then re-dissolved in 5 ml acetonitrile and cleaned up with a florisil column. Elusion of the column was done with dichloromethane and acetone in 2:1 ratio. The column elute was concentrated and redissolved in 5 ml acetonitrile for HPLC analysis. Similar methodology was followed for the soil samples. Analysis of the pendimethalin and oxyfluorfen residues were carried out using high performance liquid chromatograph equipped with Photodiode detector. A Phenomenox-C18 Column (250×4.6 mm) was used for their estimation. Mobile phase was acetonitrile with a flow rate of 0.5 ml min−1. Detector wave length for pendimethalin and oxyfluorfen was 240 and 205 nm, respectively. The presence of pendimethalin and oxyfluorfen in the samples was identified and quantified by comparison of the retention time and peak heights of the sample chromatograms with that of the standard run under identical operating conditions. Under these operating conditions, the retention time for pendimethalin and oxyfluorfen was 3.5 and 2.92 min, respectively.
Detection limit for both the compound was 0.05 ppm.
Results and discussion In the present investigation, recovery experiments were carried out at different levels to establish the reliability and validity of analytical method and to know the efficiency of extraction and cleanup procedures. To judge the efficacies of extraction and cleanup, the recovery experiments were performed. Samples of gobhi sarson, raya, cabbage, peas, garlic, and soil from control plots were spiked at levels of 0.20, 0.10, and 0.05 mg kg−1. These were extracted, cleaned, and analyzed following the method already described. The control samples from untreated plots and reagent blanks were also processed in the same way so as to find out the interferences, if any, due to the substrate and reagents, respectively. The mean percent recoveries of pendimethalin and oxyfluorfen from samples at the fortification level of 0.20 to 0.05 mg kg−1 ranged from 86 to 98 (Table 1). The average
Table 1 Recovery studies of pendimethalin and oxyfluorfen on gobhi sarson, raya, cabbage, peas, garlic, and soil (n=6) Substrates
Level of fortification (mg kg−1)
Pendimethalin Mean recovery (%)
Gobhi sarson
Raya
Cabbage
Peas
Garlic
Soil
Oxyfluorfen RSD r (%)
Mean recovery (%)
RSD r (%)
0.20
95.60
1.24
95.80
1.43
0.10
92.00
1.85
92.78
3.75
0.05
87.88
1.93
85.29
0.74
0.20
98.00
4.39
90.43
1.39
0.10
95.50
3.28
89.27
2.56
0.05
86.49
4.15
87.73
5.51
0.20
93.77
3.72
92.51
5.15
0.10
95.00
1.82
88.13
2.58
0.05
88.50
0.63
88.02
1.43
0.20
92.72
5.20
89.37
4.47
0.10
89.06
2.68
84.63
1.95
0.05
86.52
2.29
83.72
3.20
0.20
93.37
5.31
87.32
4.28
0.10
90.31
2.58
89.63
1.84
0.05
86.69
4.99
86.64
4.49
0.20
95.03
3.38
92.20
2.86
0.10
94.20
2.37
91.25
3.80
0.05
88.10
1.61
86.17
2.47
221
Environ Monit Assess (2015) 187:221
Page 4 of 6 700000
Area observed (milivolt-sec)
Fig. 1 Standard curve for pendimethalin
Area
600000 500000
y = 1E+06x - 69273 R² = 0.9956
400000 300000 200000 100000 0
0
0.1
Area observed (milivolt-sec)
recovery values were found to be more than 85 %; thus, the results have been presented as such without applying any correction factor. The calibration curve for pendimethalin was prepared by injecting different known concentrations (0.1, 0.2, 0.3, 0.4, and 0.5 ppm) of the compound. The calibration details have been presented in Table 1. A calibration curve has been plotted (Figs. 1 and 2) for the concentration of the standards injected versus the peak area observed, and the curve was found to be linear up to the lowest concentration range of 0.1 ppm. The approximate retention time was obtained at 3.5 min. Immediately after 2 h (0 day) of treatment, the average pendimethalin residue in the soil at 0– 20 cm depth was found 0.46 mg kg−1 at 0.56 kg ha−1 dose indicating that pendimethalin was evenly distributed on field surface (Table 2). With passage of time, pendimethalin residues decreased successively and reached the level of 0.26 and 0.11 mg kg−1
Fig. 2 Standard curve for oxyfluorfen
Linear (Area)
0.2
0.3 0.4 Concentration(ng)
0.5
0.6
after 7 and 15 days in 0.56 kg ha−1 treatment, respectively. Dissipation of pendimethalin was continued with time and by 45 was found to be 0.05 in 0.56 kg ha−1 treatment. However, 0.65, 0.45, 0.15, and 0.09 mg kg−1 pendimethalin residues were detected in soil at 0, 7, 15, and 30 days after application at 0.75 kg ha −1 . Pendimethalin residues were found to be below the limit of quantification after 60 days of application. Oxyfluorfen residue in the soil was studied after 0, 7, 15, 30, 45, and 60 days interval when oxyfluorfen was applied in soil at 0.17 and 0.23 kg ha−1 pre emergence. Initially, when the soil samples were taken after 2 h of spray, the residues of oxyfluorfen were found to be 0.16 and 0.21 mg kg−1 when applied at 0.17 and 0.23 kg ha−1, respectively (Table 3). The residues of oxyfluorfen were degraded gradually and reached the level of below detectability limit after 45 days in both the treatments.
1600000 1400000
Area
1200000
Linear (Area) y = 272682x + 75691 R² = 0.9947
1000000 800000 600000 400000 200000 0
0
1
2
3
Concentration (ng)
4
5
6
Environ Monit Assess (2015) 187:221
Page 5 of 6 221
Table 2 Residues of pendimethalin (mg kg−1) in the soil Sampling time (days)
at 0.56 kg ha−1
at 0.75 kg ha−1 0.65±0.05
0
a
7
0.26±0.05
0.45±0.03
15
0.11±0.06
0.15±0.02
30
0.07±0.05
0.09±0.01
45
0.05±0.04
0.06±0.01
60
BDL
BDL
a
0.46±0.049
Mean ± SD of three replications
Table 4 Residue of pendimethalin (mg kg −1 ) studied in vegetables Sampling time at 0.56 kg ha−1 at 0.75 kg ha−1 (at harvest) 2010–2011 2011–2012 2010–2011 2011–2012
75 DAS 90 DAS 90 DAS
BDL Below detectability limit; 0.05 ppm 100 DAS
The results were in accordance with the Sondhia and Dubey (2006) and Sondhia (2007). They observed that when pendimethalin applied at 0.75 kg a.i. ha−1 was found to be 0.47, 0.05, 0.04, and 0.02 μg g−1 after 15, 30, 60, and 90 days in the soil samples, respectively. Pendimethalin is known for its high adsorption onto the soil and organic matter. Pendimethalin adsorbs strongly to topsoil, and soil–water partition coefficients (Kd values) ranging from 99.8 (0.59 % organic carbon) to 1638 (16.9 % organic carbon) have been reported (Zheng and Cooper 1996). In spite of high adsorption of pendimethalin to soil, several reports indicated long persistence of pendimethalin. Jaźwa et al. (2009) reported half-lives of pendimethalin 60–62 days in the soil of fennel field. Raj et al. (1999) reported that organic matter content of the soil was responsible for high adsorption of pendimethalin. The analysis of gobhi sarson, raya, cabbage, peas, and garlic samples indicated that despite the presence of
Table 3 Residues of oxyfluorfen (mg kg−1) in the soil Sampling time (days)
at 0.17 kg ha−1
0
0.16±0.03
0.21±0.02
7
0.11±0.02
0.13±0.01
15
0.08±0.01
0.10±0.02
30
0.05±0.02
0.08±0.01
45
BDL
BDL
60
BDL
BDL
a
Mean ± SD of three replications
BDL Below detectability limit; 0.05 ppm
at 0.23 kg ha−1
165 DAS
Cabbage BDL BDL Gobhi sarson BDL BDL Raya BDL BDL Peas BDL BDL Garlic BDL BDL
BDL
BDL
BDL
BDL
BDL
BDL
BDL
BDL
BDL
BDL
BDL Below detectability limit; 0.05 ppm
high level of pendimethalin residues in soil surface, the residues of pendimethalin at 0.56 and 0.75 kg a.i. ha−1 were found to be below the limit of quantification in samples collected at their harvestable stage (Table 4). Similar results were observed in case of oxyfluorfen at both the dosages (Table 5). The herbicides were sprayed at the time of sowing, and the sampling was carried out at harvesting. There was a long time gap between herbicide application and analysis resulting in its degradation. Soil microbes might be one of the factors responsible for degradation of these herbicides. Residues of pendimethalin applied 1 kg ha−1 pre emergence to tomato, cauliflower, and radish crops were below detectability limit at the time of harvest of these vegetables (Sondhia 2013). The study indicated that pendimethalin and oxyfluorfen applied at recommended doses in the
Table 5 Residue of oxyfluorfen (mg kg−1) studied in vegetables Sampling time at 0.17 kg ha−1 at 0.23 kg ha−1 (at harvest) 2010–2011 2011–2012 2010–2011 2011–2012 Cabbage 75 DAS
BDL
BDL
BDL
BDL
BDL
BDL
BDL
BDL
BDL
BDL
Peas 100 DAS
BDL Garlic
165 DAS
BDL
BDL Below detectability limit; 0.05 ppm
221
Page 6 of 6
present trial are safe for use in the gobhi sarson, raya, cabbage, peas, and garlic. Acknowledgments The authors are thankful to the Heads of Department of Agronomy and Entomology, PAU, Ludhiana for providing the necessary research facilities.
References Anonymous (2012) Package of practices for Kharif crops. Ludhiana: Punjab Agricultural University. Bhullar, M. S., Kamboj, A., & Singh, G. P. (2006). Weed management in spring planted sugarcane (Saccharum officinarum) based intercropping systems. Indian Journal of Agronomy, 51, 183–185. Dharni, K., Singh, R., & Sharma, S. (2007). Sugarcane market scenario. Progressive Farming, 43, 16–27. Hunsingi, G. (1993). Production of sugarcane—Theory and practice (pp. 144–147). Berlin: Springer Ver Lag. Jaźwa, A., Szpyrka, E., & Sadło, S. (2009). Disappearance of pendimethalin in soil and its residue in ripe fennel. Journal Central European Agriculture, 10, 153–158. Kanwar, R. S., Singh, S., Sodhi, R. S., & Garcha, A. I. S. (1992). Comparative performance of different herbicides combination for weed control in sugarcane. Indian Sugar, 42, 621–625. Lal, M., & Singh, A. K. (2004). Technology package for sugarcane based intercropping systems. Lucknow: Indian Institute of Sugarcane Reasearch. Mathur, B. K., Singh, A., & Bhadawire, V. S. (1968). Intercropping in sugarcane. Indian Sugarcane, 13, 1043– 1048.
Environ Monit Assess (2015) 187:221 Misra, G. N. (1964). Mixed cropping effects of certain intercrops on the yield and juice quality of sugarcane. Indian Sugar, 14, 1–17. Ponnusamy, K.P., Santhi, & Sankaran, S. (1996). Effect of herbicides on growth and yield of early sugarcane var. CoC 671. Pestology, 20, 22–26. Raj, M. F., Patel, B. K., & Shah, P. G. (1999). Adsorption and desorption of pendimethalin, fluchloralin and oxadiazon on soils. Pesticide Research Journal, 11, 162–167. Sathyavelu, A., & Somasundaram, E. (2002). Integrated weed management in sugarcane. Indian Sugar, 53, 871–873. Shafi Nazir, M., Abdul, J., Imtiaz, A., Shah, N., & Iftikhar, H. B. (2002). Production potential and economics of intercropping in autumn planted sugarcane. International Journal of Agricultural Biology, 4, 140–142. Singh, A. K., Lal, M., & Archana, S. (2008). Effect of intercropping in sugarcane (Saccharum complex hybrid) on productivity of plant cane—Ratoon system. Indian Journal of Agronomy, 53, 140–144. Sondhia, S. (2007). Evaluation of leaching potential of pendimethalin in clay loam soil. Pesticide Research Journal, 19, 119–121. Sondhia, S. (2013). Harvest time residues of pendimethalin in tomato, cauliflower, and radish under field conditions. Toxicology and Environmental Chemistry, 95, 254–259. Sondhia, S., & Dubey, R. P. (2006). Determination of terminal residues of butachlor and pendimethalin in onion. Pesticide Research Journal, 18, 85–86. www.Indiastat.com visited on March 9, 2015. Zheng, S. Q., & Cooper, J. F. (1996). Adsorption, desorption and degradation of three pesticides in different soils. Archives of Environmental Contamination Toxicology, 30, 15–20.
