Behaviour of the soil residues of the herbicide quinclorac in the micro-ecosystem (pot)

Micro-ecosystem(pot)중 제초제 quinclorac 토양잔류물의 행적

  • Ahn, Ki-Chang (Department of Agricultural Chemistry, College of Agriculture, Chungbuk National University) ;
  • Kyung, Kee-Sung (National Institute of Agricultural Science and Technology, RDA) ;
  • Lee, Jae-Koo (Department of Agricultural Chemistry, College of Agriculture, Chungbuk National University)
  • 안기창 (충북대학교 농과대학 농화학과) ;
  • 경기성 (농업과학기술원 작물보호부 농약개발과) ;
  • 이재구 (충북대학교 농과대학 농화학과)
  • Published : 1998.12.30

Abstract

Rice plants were grown for 42 days in the specially made micro-ecosystem(pot) containing two different soils treated with fresh and 60-day-aged residues of [$^{14}C$]quinclorac, respectively, to elucidate the behaviour of the herbicide quinclorac residues in the soils. Amounts of $^{14}CO_{2}$ evolved from two soils treated with different residues with and without vegetation were all less than 2.2% of the total $^{14}C$, indicating that there was little microbial degradation of quinclorac in soil. $^{14}C$-Radioactivity absorbed and translocated into rice plants from soil A and B containing fresh quinclorac residues was 8.4 and 24.2%, respectively, of the originally applied $^{14}C$, while 5.5 and 17.7%, in aged residue soils. These results indicate that larger amounts of $^{14}C$ were absorbed by rice plants from soil B with less organic matter and clay than soil A, and the uptake of [$^{14}C$]quinclorac and its degradation products decreased with aging in soil. After 42 days of rice growing, 84.5 and 61.8% of the $^{14}C$ applied freshly to soil A and B, respectively, remained in soil, whereas, in the case of aged soils, 86.3 and 67.7% of the $^{14}C$ applied did. Meanwhile, without vegetation, more than 98.3% of the $^{14}C$ applied, in both fresh and aged residues, remained in soil, suggesting that quinclorac was relatively persistent chemically and microbiologically. Most of the non-extractable soil-bound residues of [$^{14}C$]quinclorac were incorporated into the organic matter and largely distributed in the fulvic acid portion.