In light of the rapidly growing human population, extensive pesticides have been utilized to maximize crop production. This has become a major environmental concern. To assess the influence of commonly used pesticides on soil microorganisms counts and microbial activities in the form of CO2 production, a factorial experiment was conducted. Herbicide (Glyset I.P.A, Glyphosate 48%) and insecticides Miraj (Alphacypermethrin 10%) and Malathion (50% WP) were separately added to the soil at 0, 50, 100 and 200 ppm and incubated in the laboratory at 30 °C. The counts of bacteria, fungi, actinomycetes and CO2 production were examined weekly for 7 consecutive weeks. The results demonstrated that the addition of the three mentioned pesticides significantly decreased the microbial activities and counts of soil bacteria, fungi and actinomycetes. The observed effect was depended upon the type and amount of pesticide as well as the length of incubation period. The microbial activities and the number of bacteria, fungi, and actinomycetes were inversely proportional to the concentration of pesticides added to the soil. In most treatments, soil samples treated with 200ppm of Malathion demonstrated the lowest microbial activities and counts of bacteria, fungi and actinomycetes. This study suggests that the investigated pesticides negatively affect microbial counts and activity in soil, which confirms and reinforces previously reported environmental concerns.

The experiment under lab condition was conducted to investigate the effect of petroleum hydrocarbon contamination on soil microorganisms and biodegradation. The experiment was conducted in 12 treatment and three replication. The treatments include soil contaminated with Kerosene, Diesel, lubricate oil and used lubricate oil in three concentration 0%, 5%, and 10%. contamination with hydrocarbons significantly decreased the count of heterotrophic bacteria and there was reversal relationship between the contaminant concentration and the count of heterotrophic bacteria. The results indicated soil contamination with hydrocarbons significantly increased the count of Hydrocarbon Utilizing Bacteria (HUB). The effect of petroleum hydrocarbons on fungi count differed according to the type of hydrocarbons, concentration of contaminant and the periods of incubation. Our results show that soil contamination by hydrocarbons caused significant increase in actinomycetes count at all hydrocarbon types and concentrations except 5% used and non-used lubrication oil. The higher percentage of biodegradation in hydrocarbons contaminated soil 49.6% was recorded in soil contaminated with 5% kerosene while the lower percentag10.8% was recorded with soil contaminated 10% lubricate oil.

Studies have shown arbuscular mycorrhizal fungi (AMF) enhance phosphorus (P) uptake and drought tolerance in maize (Zea mays L.) grown in semiarid soils. However, little is known regarding the contribution of AMF to maize treated with different levels of phosphorus and grown in different soil moisture levels. This study was conducted to determine the effects of AMF (Glomus fasciculatum) inoculation on growth and P uptake of maize treated with different levels of soil P and soil moisture. Different P levels (0, 50, and 100 kg P ha -1 ) were applied on maize grown in soils with and without mycorrhizal fungi, and at different moisture levels producing -0.05, -0.4, -0.8, and -1.5 MPa of drought stress. Increasing P rates significantly (p < 0.05) reduced mycorrhizal colonization. Mycorrhizal colonization was higher under moderate than under lower soil moisture levels. Drought stress × soil P content × AMF inoculation interaction had significant (p < 0.05) effect on maize shoot and root dry weight and tissue P concentration. Overall, results of this study suggest that mycorrhizal inoculation enhances P uptake and maximizes maize biomass under low, moderate, and high soil moisture conditions without P applications. Except for the lowest soil moisture level (-1.5 MPa), mycorrhizal plants produced higher biomass, with greater tissue P content than nonmycorrhizal plants at all soil P and soil moisture levels. These results indicate that establishing efficacious AMF with maize could be an efficient alternative for growers than relying on P fertilizer application and its associated costs and environmental concerns.

In order to investigate occurrence and distribution of Arbscular Mycorrhizal Fungi (AMF) in Aljabal Alakhthar area, east Libya. Roots and rhizosphere soil of 49 cultivated plants belonging to 7 families from 8 locations were collected. The percentage of root colonized by AMF was estimated. Spores extracted from soil samples were counted and morphologically identified to genus. The results indicate that all examined plants were colonized by AMF. Colonization rate and spore abundance differed according to location and plant. Colonization rate range from 97% in Petro selinum at Alqubbah location to 29 % in Vicia faba at Almarj. While spore abundance range from 992 spores / 100gm soil accompanied with Vicia faba at West alawilia location to 121 spores / 100gm accompanied with Avena sativa at Alqubbbah. As average of all locations, the plants belonging to Apiaceae had the highest colonization percentage where the plants belonging to Cucurbitaceae had the highest spore abundance. Lumloda location records the highest colonization rate. There was no correlation detected between root colonization rate and spore abundance. However, soil available phosphorus and clay percentage negatively correlated with degree of AM root colonization. Positive correlation was found between silt percentage and spore abundance. Glomus was the most abundant genus in all studied locations followed by Acaulosora, Gigaspora and Scutellospora

This experiment was conducted at the wood shader according to complete randomized design by using clay loam texture soil columns with 15 cm diameter and 40 cm height. which have been accomplished by compacted the soil after wetning it to the optimum water coutent for compaction by procter equipment to reached the bulk density