I want to know the permissible limit of herbicides (2,4,D and Atrazine) in agricultural and riparian soil? What is impact on Riparian biodiversity if they increase with their permissible limit?
This article may be the answer to your questions. I wish to be useful.
Best wishes,
This article may be the answer to your questions. I wish to be useful.
Best wishes,
Dear A N Singh,
Ayşe Yazlik provided a very useful article. Few more things are added and hope they would be of any use.
First, regarding the permissible limit in agricultural soil, referring to the article by Walters J and other such literatures, the half life of 2,4-D is very short (less than 15 days). In soil, 2,4-D is reported to affect seed germination (link below)
http://www.jstor.org/stable/pdf/4040499.pdf?seq=1#page_scan_tab_contents
However, in most cases the effect is in terms of delay in seed germination, and decrease in seed germination to less than 80% is at a concentration above 0.07% (700 ppm).
http://science.sciencemag.org/content/105/2724/283
In some works, the dose of applied 2,4-D affecting seed germination (less than 80%) had been reported highr (1000 ppm for Hibiscus). We observed no detectable level (0.1 ppm) of 2,4-D residue in soil (sandy clay loam) after application for 10 crop cycles of transplanted rice-rice sequence (applied 0.75 kg a.i./ha twice in a year).
Regarding the second point of query, i.e. permissible limit in riparian soil the following information may be observed:
Canada’s Guidelines for Canadian Drinking Water Quality has established a maximum acceptable concentration (MAC) of 0.1 mg/L.
http://healthycanadians.gc.ca/publications/healthy-living-vie-saine/water-dichlorophenoxyacetic-eau/index-eng.php
This had been fixed assuming intake of 1.5 litre water for a person having average bodyweight of 70 kg. So, a soil can take higher load of 2,4-D with a short half life.
Similar to soil, the half life of 2,4-D in water is also short (about 9 days). We did not observe any detectable level (0.05 ppm) of 2,4-D residue in water at 15 days after application (1 kg a.i./ha from an initial applied concentration of 0.13 ppm).
The riparian vegetation is usually dominated by grassy species, while the target species for 2,4-D is broadleaved plants. Thus, for riparian soils too the 2,4-D concentration affecting biodiversity may be set similar to agricultural soils.
I am so thankful to borah sir and Ayse for providing a good information and suggestion definitely it help me. Dear Borah Sir, Please send me full article at my mail [email protected] because I'm unable to download the linked articles (http://science.sciencemag.org/content/105/2724/283, and http://healthycanadians.gc.ca/publications/healthy-living-vie-saine/water-dichlorophenoxyacetic-eau/index-eng.php)
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