Posted 26 November 2014. PMN Crop News.
Soil Sampling Techniques
Determining sampling zones, random sampling and multiple cores are essential to a good soil sampling procedure
Source: Penn State University Press Release. agsci.psu.edu
University Park, Pennsylvania (November 4, 2014)--With corn grain yields coming in at near record highs in Pennsylvania, it is important to remember the basis for those yields comes from a proper crop nutrition program and fundamental soil testing.
Over a month ago, an article titled Some Soil Testing Ideas reminded producers of some simple tips to improving soil sampling methods. This article is intended to expound upon those ideas.
Developing a plan
How many soil test kits do I need? This information should be well outlined for producers that soil test regularly, but sometimes management zones can change slightly over time or with the addition of new data to the system. When selecting soil testing areas, or management zones, first consider the lay of the land. The top of the knoll is likely going to have a different soil then that at the bottom of the slope. Are there any abnormal areas? Wet spots, sink holes or other irregular areas of the field should not be part of the sample. Sampling zones should be no more than 10 acres in size. The more information available, the more soil sampling zones can be tailored to the needs of the farm business. Another layer in determining sample areas can be defined by the soil type. A map of soil types for your operation can be found using NRCS Web Soil Survey.
Further information that might influence management zones for a producer is field history and yield data. If one field has been managed as two fields in the recent past, two different soil tests may show differences in this management, though the fields have now been joined.
The data available for collection in crop production seems infinite. There are other ways of soil sampling that may be used in different situations. The most important concept to remember is that one soil sample should contain multiple cores from throughout one field or area. One soil core is not representative of typical field conditions and may skew the big picture on your farm.