Abstract
Soil testing has advanced as a science and has become a tool widely used in making fertilizer recommendations. One of the basic components for ensuring reliability of recommendations is calibration of soil test results to determine the proper match of fertilizer recommendations with the soil test level for each nutrient and crop. Generally, calibration has been accomplished on small plot areas and is quite accurate. Even though there is nutrient variability within small areas, the potential for variability is much greater on a field basis. An important factor in making reliable fertilizer recommendations is the assumption that the soil sample itself accurately represents a field. Large variations in fertility levels and pH within a field can result in poor recommendations. Therefore, the nutrient variability within a field is of interest and importance. In some cases, the nutrient variability within a field can be caused by a number of things such as soil erosion and deposition, combining of fields, past history, fertilization and manure application patterns, soil types and other factors. Large variability within a field has been proven to cause variable yields. Soil test records from many fields over a number of years show that the extent of soil test variability is dependent on the field. Because of this, some fields show little change in soil test levels from year to year while other fields show large changes in the nutrient status from year to year. Such large yearly changes can come from a combination of primarily four sources: 1) Variability in the field as described above; 2) How the soil sample is taken (number of cores, depth, time of year, etc.); 3) Quality control within the laboratory (the capability of the lab to reproduce its results); and 4) Fertilizer applied during the year and time of soil sampling relative to fertilizer application and crop growth. We have closely monitored a field for a number of years to evaluate the effect of these factors on making lime and fertilizer recommendations.
Publication Date
1993
Volume
14
Number
1
Repository Citation
Murdock, Lloyd W.; Kirkland, Dan; Gillespie, Phil; and Gray, Tim, "Soil Testing: Field, Sample and Laboratory Variability" (1993). Soil Science News and Views. 73.
https://uknowledge.uky.edu/pss_views/73
