The fertility status of soils and the soil ability to supply nutrients to the cropped plants are subjects of important interest in the agronomic research. Although the indexes (chemical and biological) of fertility status of soils are predictive of their plant nutrients supplying abilities, various factors like soil-nutrient interaction, root-nutrient interaction, soil pH, soil water status, soil ecology (environmental), soil morphology, and also plant morphology and physiology differently but interdependently affect the nutrient supplying characteristics of soils to the growing plants. Thus, research attentions focus on the assessment of the fertility status of soils and the measurement of the parameters that are contributory to the nutrients availabilities, mobility and the soil supplying properties relative to the crop of interest. Such information is valuable to successful manipulation of soils through chemical and/or biological means to enhance their productivity.