Impact of Some Pesticides on Total Counts of Soil Non- Symbiotic Nitrogen-Fixing Bacteria, Particularly Azotobacter sp.

Impact of Some Pesticides on Total Counts of Soil Non-Symbiotic Nitrogen-Fixing Bacteria, Particularly Azotobacter sp.



Nashmeel Saeed Khudhur1 and Abdul-ghany Omer Ismaeel Sarmamy2



1 Department of Environmental Science, College of Science, University of Salahaddin, Kurdistan Region, Iraq
2 Department of Biology, College of Science, University of Salahaddin, Kurdistan Region, Iraq
1 E.mail: nashmeel@gmail.com





Article info

Original: 1 June. 2015

Revised:28 June. 2015

Accepted:30 August. 2015

Published online:  20 March. 2016




Key Words:

Soil pollution
Pesticides
Non-symbiotic
nitrogen-fixing
bacteria
Azotobacter sp.


Abstract

A pot experiment was conducted to evaluate the effect of glyphosate herbicide (nphosphonomethyl
glycine), mancozeb fungicide ([[1,2-ethanediylbis-
[carbamodithioato]] (2-)] manganese mixture with [[1,2-ethanediylbis-
[carbamodithioato]]-(2-)] zinc) and diazinon insecticide (O, O-diethyl O-[6-methyl-2-(1-
methylethyl)-4-pyrimidynyl]), three soil orders and two soil moisture contents (50% and
100% of field capacity) and their combinations on soil total non-symbiotic nitrogenfixing
bacteria particularly Azotobacter sp. counts. This experiment last for two months
from the 6th of Jun until the 8th of August 2011 with five sampling periods at biweekly
intervals. Factorial experiment (4×3×2) with Completely Randomized Design (CRD) and
three replications was used and the means were compared using Revised Least
Significant Differences (R.LSD) at the level of significant of 0.05. Significant results
were obtained at the last two scheduled period’s sampling of 4th and 5th, and the results
showed that: Mancozeb fungicide decreased total Azotobacter sp.; Diazinon insecticide
decreased both total non-symbiotic nitrogen-fixing bacteria and total Azotobacter sp.;
Agholan soil (order Entisols) showed the greatest increase in soil total non-symbiotic
nitrogen-fixing bacteria. 50% soil moisture content revealed the greatest reduction total
Azotobacter sp. while, 100% soil moisture content showed the greatest increase in soil
total Azotobacter sp. count. The combinations among: glyphosate, Agholan soil and
100% moisture combination showed the greatest reduction in total non-symbiotic
nitrogen-fixing bacteria and total Azotobacter sp.





Ċ
Ramyar Abdolrahman Taimur Ismail,
Mar 20, 2016, 5:04 AM