Agricultural production and productivity are directly linked with nutrient availability. For sustained high crop yields, the application of nutrients is required. The term ‘nutrient availability’ has been used and defined in many ways. Hence, any use of the term needs to be accompanied by an appropriate definition. The Soil Science Society of America has defined available nutrients: (1) the amounts of soil nutrients in chemical forms accessible to plant roots or compounds likely to be convertible to such forms during the growing season, and (2) the contents of legally designated available nutrients in fertilizers determined by specified laboratory procedures which in most states constitute the legal basis for guarantees. Review journals are the evaluation of work by one or more people with similar competences as the producers of the work (peers). It functions as a form of self-regulation by qualified members of a profession within the relevant field. Peer review methods are used to maintain quality standards, improve performance, and provide credibility.