No abstract

Deltamethrin [(S)-a-cyano-3-phenoxybenzyl ci's-(lfi,3fi)-2,2-dimethyl-3-(2,2-dibromovinyl)cyclopropanecarboxylate] labeled with 14C at the methyl or benzylic position was applied to an organic soil at 10 mg/kg in a laboratory incubation study. A steady decrease of extractable 14C residues was accompanied by a corresponding increase of bound 14C residues over a 180-day incubation period. The degradation of deltamethrin was slower under the anaerobic than aerobic condition. The insecticide was degraded in the organic soil by hydrolysis at the ester linkage followed by the formation of oxidative products. A small proportion of bound 14C residues in the incubated soil was identified as 3-(2,2-dibromovinyl)-2,2-dimethylcyclopropanecarboxylic acid, whereas the remainder constituted unidentified products. The soil containing bound 14C residues (19% of initial 14C applied) was fractioned into humic substances. The humin fraction contained an appreciable amount of bound 14C residues.Deltamethrin [(S)-a-cyano-3-phenoxybenzyl cis-(lfi,3fi)-2,2-dimethyl-3-(2,2-dibromovinyl)-2,2-dimethylcyclopropanecarboxylate] is a pyrethroid that is also known as decamethrim and NRDC 161. The insecticide is active against a wide range of insects that attack crops, animals, and man. While there is ample information available in the literature about its photochemistry (Ruzo et al., 1977) and metabolism in plants (Ruzo and Casida, 1979) and animals (Ruzo et al., 1978(Ruzo et al., ,1979, little is known about its persistence and degradation in soil. The limited published work reveals that deltamethrin is immobile in mineral soils (Kaufman et al., 1981;Hill, 1983) and a half-life in the range of 1-8 weeks has been reported (Chapman et al., 1981; Miyamoto and Mikami, 1983;Hill, 1983).Deltamethrin has been recommended for foliar applications on various vegetable and field crops (FAO, 1981). It is possible that this insecticide will be found useful to control numerous species of insects in vegetable crops grown in organic soils that occur widely in eastern Canada and are of great economic value for vegetable production.

No abstract

No abstract

No abstract

The effect of-freezin,g and duration of storage weeks, after which a prominent decrease ocol lrozen sorl on free amino acids and sugars curred. Essentially there was no difference bewas evalttated. Freez:ing caused a marked in-tween single freeie-thaw and multiple freezecrease rn the total anlount of free amino acids thaw cycles. In general, soil respiiation and an.d-sugar,s extracted, The level of free amino dehydrogenase ac'tivity paralleled^the level of acids and sugars, in frozen soil, remained extracta6le free amino icids and sugars. fairly constant up t,c a storage period of 6

Five soils were subjecteo ," ,"fi:;ll:Tof 1" ",rd -14"C for 3 ."veeks.Freezing caused a marked increase ln the total amount of free amino acids extracted, The amounts of free amin,: acids released were greater in soils',lhere decomposition of organic mater \var; more complere. wh'ile pror-nged t,or"g" of soil at 1"c had no measurable eiTecr on thc free amino acidi rer""iJ, it"i"[" over a.long period,at -r4'c decreased the free amino acid co'tent.

The free amino acids and the total ninhydrin-reacting material