The aim of every agricultural system is to maximize the yield and quality of crops while minimizing the cost of production and environmental pollution, thus maintaining sustainability. One way of achieving this is through the control of agricultural pests like weeds by the use of herbicides. Chemical herbicides have certain long-term disadvantages which include the killing of both target and non-target organisms, accumulation in the food chain , soil degradation, changes in the ecosystem, changes in the biological diversity, chemical and physical properties of the soils. The role of soil micro-organisms in nutrient and energy fluxes and their sensitivity to changes in soil conditions are factors to consider before any introduction of chemicals into the existing system. The Annual Wormwood (Artemiesia annua) weed suppressive activity has been attributed to the release of allelochemicals into the soil. The presence of a wide array of biologically active constituent like Artemisinin, a sesquiterpene present in the plant, takes part in the allelopathy. Aromatic Volatile oil, artemisic ketrone, 1,8 – cineole camphor, germaceral D, camphene hydrate are also products with characteristic allelopathy for effective weed control. The objective of the study is to investigate the reactions of soil micro-organisms and changes in chemical properties brought about by the application of the crude extract of Artemiesia annua. For this study, soil samples from the University of Calabar, Botanical Garden (ie. Soil from continuously cultivated soil and forest soil both Alfisols) were used through incubation studies to determine the effect of Artemiesia annua crude extract on their biochemical properties. The microbial and chemical analysis were carried-out using 3 levels of concentrations (1.25%, 2.5%, and 5%) and the control, and the resulting mean values were compared to determine the best levels of concentration to use. The evaluation showed six isolates, Baccillus subtitis, Micoccocus spp, Arthrobacter spp, Pseudomonas spp, Klebsiella aerogenes, streptococcus auereus with Arthrobacter showing the highest prevalence. The result showed the highest number of prevalence in all the isolates at 5% concentration. The fungal isolate identified included, Rhizopus nigricans, Mucor, Aspergillus niger and penicellium notatum with Aspergillus and Rhizopus showing the highest prevalence and 2.5% concentration level showing the best level of application. The result of the soil chemical analysis shows that at the 3 levels of concentration – 1.25%, 2.5% and 5% the soil pH changed from 5.02 to 4.36, 4.17 and 4.3, Organic Carbon changed from 1.08 to 1.39, 1.17 and 1.34, total nitrogen from 0.0% to 1.13, 0.1 and 1.13%, available phosphorus from 94.75mg/kg to 98.87mg/kg, 97.30mg/kg and 99.41mg/kg, soil exchangeable bases from 2.62cmol/kg to 2.90, 3.44 and 3.26cmol/kg and exchangeable acidity from 2.65cmol/kg to 3.92, 3.73, and 3.92cmol/kg respectively. This confirmed the best level of application to be 2.5% and 5%. Therefore Artemiesia annua crude extract increases both microbial population and chemical properties of the soil and the best level of application as herbicides is 5% concentration. Key Words: Annual Wormwood, biological, chemical, crude extract and microbial population.