The residual effect of the herbicide Tordon 22-K on the microflora and nutrient status of the soil
Goguadze, V.D.; Gobronidze, E.A.; Gogiya, L.G.
Subtropicheskie Kul'tury (3): 157-159
1972
ISSN/ISBN: 0491-4031 Accession: 000243552
Picloram-potassium (as Tordon 22K) at 2 kg/ha was applied annually in 1968-70 on alluvial soil in a citrus nursery and the top 30 cm of soil was sampled and analysed. Picloram increased populations of soil micro-organisms from 7-10 millions to 8-12 millions/g dry soil in the first 2 years but reduced them from 15 to 11 millions/g in the third year of application; spore-forming ammonifying bacteria, N fixers and nitrifiers were increased compared with the control while fungi and cellulose-decomposing bacteria were decreased in the second and third years. The amount of nitrate N was doubled and trebled, respectively, in the second and third years of application. Picloram had no significant negative effects on the nutrient status or microflora of the soil in the first 2 years but in the third year it reduced soil nutrients, except nitrate N, and some groups of micro-organisms.