An understanding of soil chemical properties is important because of their effect on nutrient availability to plants. Also, these properties may usually be favorably altered with the use of lime and/or fertilizer materials. Many plants need 18 elements (see Table 1) for normal growth and completion of their life cycle. These elements are called the essential plant nutrients. Soil amendments containing the essential plant nutrients or having the effect of favorably changing the soil chemistry have been developed and used to enhance plant nutrition. These amendments are our lime and fertilizer materials.
With the development of these modern lime and fertilizer materials, as well as equipment for handling and application, amending soil chemical properties became a cheap and easily accomplished task relative to the high returns often achieved. Soil testing developed as a means for answering questions about need for a particular amendment (status of the soil's fertility) and uncertainty about how much to add. The two basic questions answered from the soil testing results of modern laboratories are: (1) Which soil amendments (specific types of fertilizers and/or liming materials) does this soil need? (2) How much of the amendments are needed to get the most return on dollars spent? Our lime and fertilizer materials are developed primarily from finite and non-renewable resources. Therefore, these preceding questions are extremely relevant to our concerns about the efficient and environmentally sound use of such resources.
Other diagnostic techniques, such as plant analysis, may sometimes be useful as a supplement to soil test information or for "troubleshooting" and monitoring applications. The mineral components of the plant (essential plant nutrients) are supplied to the plant by and through the mediums of air, water and soil.
"PB1637 Fertilizers and Their Use," The University of Tennessee Agricultural Extension Service, PB1637-10M-11/99 E12-2015-00-117-00, http://trace.tennessee.edu/utk_agexcrop/52