Soil Testing For Nutrient Evaluation And Chemical Problems
C. Owen Plank
Associate Professor, University of Georgia
Determining the fertility level of a soil through a soil test is the first step in planning a sound lime and fertilize program. This step is very important in turf production because the soils on which turfgrass is grown vary considerably in their chemical and physical properties. Therefore, to maintain normal plant growth, lime, fertilizer, and other soil amendments must be supplied in sufficient quantity to meet the crops requirement and to alleviate undesirable soil conditions. A soil test provides the means of monitoring the soil so deficiencies, excesses, and imbalances can be avoided.
Chemical soil testing is a widely used management tool for crop production, with more than 400 laboratories in the USA and 200 in Canada offering services (Jones, 1992). A recent survey conducted by the Soil and Plant Analysis Council, Inc. in conjunction with the USDA showed that commercial (private), and state (government) laboratories in the US analyze in excess of 2.7 million soil samples annually (Plank, 1997).
Soil testing may be defined as a chemical assessment of the relative fertility level of a soil. Soil tests are used most extensively for predicting limestone and nutrient needs for adjustment by liming and fertilization. They are also used for identifying nutrient deficiencies, evaluating potential excesses or imbalances of essential nutrients, heavy metals, or salts, and assessing other important soil chemical aspects (organic matter content, cation exchange capacity, etc.) that may influence turfgrass growth.
The nutrient status of turfgrass landscapes can be based on a combination of:
• soil testing.
• plant tissue analysis, either as a one-time diagnosis of a nutrient deficiency or nutrient/element toxicity, or on a continuous monitoring basis.
• plant visual symptoms on an individual leaf, single plant, or across a landscape.
• experience and knowledge of the turfgrass manager concerning turf nutritional needs under his/her specific climate, soil, use, and budget (Carrow, 1995).
The focus of information on this Web site is on the use of soil testing for assessing soil nutrient status and the components of a soil test program; namely, field sampling and sample preparation, extraction and chemical analysis, interpreting the analytical results and recommendations. For additional information, publications are available on soil testing (Christians, 1993; Haby et al.,1990; Jones, 1992; Westerman, 1990) and soil fertility/plant nutrition (Christians, 1993; McCarty et al., 1993; Mortvedt et al., 1991; Tisdale et al., 1993; Turner and Hummel, 1992).