Assess and Map Your Soils

Assessing soil health is a critical aspect of best management practices implementation, as underscored in the BMP statement:

Determine accurate supplemental nutrient needs based on soil chemical and physical analysis. On sand-based areas, consider foliar testing as a diagnostic tool.

The soil on your property has enormous environmental, and ultimately, economic value. You cannot implement a fully aligned BMP program until soils are properly assessed. Soil health, by definition, includes the physical, chemical and biological properties of the soil. Management efforts typically focus primarily on maximizing the parameters in each of these categories for agricultural crop production. However,targets for these soil health measurements are becoming clearer, which will assist superintendents in growing healthy, dense turf.

To begin a soil health assessment, start with the Web Soil Survey. UW-Madison Professor Doug Soldat published a great article in 2015 outlining the importance and practical use of the Web Soil Survey tool: Here’s my favorite quote from the article:

The Web Soil Survey is a powerful tool that has many applications for site assessment and planning. The maps can be a powerful communication tool to explain to your golfers, parents, customers, board members, or supervisors about the challenges of growing turf on your site.”

Soil survey maps provide excellent information for your records to justify certain needs or assist in diagnosing problems. Of course, they can also be used to target soil samples from areas with known soil type differences to develop a more practical map that includes additional physical, and some chemical, properties. Knowing these properties is critical to assessing water quality risks from nutrient applications (e.g. potential for leaching), to determining the need for nutrient applications and to interpreting overall soil health.

Of course, more detailed chemical and physical analyses based on laboratory results are useful on large managed turf areas such as fairways and roughs, where large scale nutrient applications are made and greater risk to water quality (e.g. runoff or leaching) exists. Currently, the level of interpretation and practical value of chemical and biological tests is limited. However, it is important to know the physical properties, drainage class, and pH of soils on your entire property that are managed in some way, from native areas to putting surfaces. Therefore, consider the following incremental approach to BMP implementation when developing a nutrient management program:

A good practice is to assess the chemical and physical analysis of your regularly fertilized soils using a Minimum Level for Sustainable Nutrition (MLSN) Guideline interpretation, as well as looking at overall turf quality and growth, when developing a nutrient management program. Make accurate supplemental nutrient applications to targeted areas of established need.

A better practice is to use the Web Soil Survey as a guide to classify and sample all soils on the property using the MLSN interpretation and performance variables (quality and growth). Make supplemental applications of nutrients based on large-scale mapping in targeted areas of well-established needs.

The best practice would be to implement the above Web Soil Survey-driven sampling program and use appropriate interpretation and performance variables as layers in a GIS database built from the sampling locations. Use this GIS database of soil properties for GPS-based Variable Rate Application equipment for precise supplemental nutrient applications to targeted areas of well-established need.