Volume III: Nutrient Use and Management on U.S. Golf Courses
A comprehensive look at nutrient management on golf courses in the United States.
About this report
Volume III covers the nutrient use and management survey, the third of the five surveys in the Golf Course Environmental Profile. The goal of the research is to develop a profile of golf courses that will establish a baseline of environmental performance so that changes over time can be measured and evaluated.
The objectives of the nutrient use and management survey were to determine:
- the amount of nutrients applied to golf courses
- the sources of the nutrients applied
- factors considered in nutrient application decisions
- whether superintendents use written nutrient management plans or operate under governmental restrictions
- how fertilizers are stored and how often fertilizer application equipment was calibrated
Golf course superintendents (16,386) at golf facilities in the U.S. were invited to participate in this survey. A total of 2,561 completed surveys were returned, yielding a 15.6 percent return rate. Data were analyzed and compared for facility type, maintenance budget and across seven agronomic regions – Northeast, North Central, Transition, Southeast, Southwest, Upper West/ Mountain, and Pacific.
Three elements — nitrogen, phosphorus and potassium — are considered primary macro-nutrients because they are often required in larger quantities than are readily available through natural soil processes.
The nitrogen content of fertilizer is expressed as nitrogen (N), the phosphorus content is expressed as phosphate (P2O5), and the potassium content is expressed as potash (K2O). Fertilizer recommendations, fertilizer rates and the annual amount of fertilizer applied are usually expressed as nitrogen, phosphate (rather than phosphorus), and potash (rather than potassium). The terms phosphate and potash will be used in this report when referring to fertilizers containing phosphorus.
Superintendents were asked to indicate the rate of application of nitrogen, phosphate and potash to greens, tees, fairways, rough, practice areas, turfgrass nurseries, grounds and no-mow/native areas. Superintendents generally express nutrient application rates in pounds per 1,000 square feet, and it is expressed in this manner in the report. Total use of nutrients is expressed in pounds per acre (1 acre = 43,560 square feet).
Summed over all golf course components and all golf courses, in 2006 a total of:
- 101,096 tons of nitrogen were applied to 1,311,000 acres (154 pounds of nitrogen per acre)
- 36,810 tons of phosphate were applied to 1,131,000 acres (65 pounds of phosphate per acre)
- 99,005 tons of potash were applied to 1,260,000 acres (157 pounds of potash per acre)
These application rates are within the guidelines recommended by university scientists.
One way to put nutrient use on golf courses in context is to compare it with nutrient use by other agricultural crops in rate per acre applied and total amount applied (rate per acre multiplied by the number of acres fertilized). Nutrient use of corn and tomatoes were chosen for comparison with nutrient use on golf course turfgrass.
Corn is a widely grown agronomic crop, and tomatoes are a high-value, intensely maintained vegetable crop. When the rate of application of fertilizer applied to turfgrass on golf facilities within the U.S. is compared to corn and tomato production, turfgrass on golf courses is fertilized at a slightly higher rate than corn and at a slightly lower rate than tomatoes.
Turfgrass on golf courses is grown on slightly less than 1.5 million acres, and those acres are fertilized with 101,096 tons of nitrogen, 36,810 tons of phosphate, and 99,005 tons of potash. Corn, which is one of many crops grown nationwide, is grown on over 76 million acres and is fertilized with 4,690,000 tons of nitrogen, 1,696,000 tons of phosphate, and 1,901,000 tons of potash. While the total amount of nutrients used at golf facilities is considerably less than corn, golf facilities should incorporate environmental stewardship practices to protect water resources.
Nitrogen fertilizer sources
For 18-hole golf facilities nationally, slow-release nitrogen sources accounted for 64 percent of the nitrogen applied, and quick-release nitrogen sources accounted for 36 percent. Organic nutrient sources were applied to 66 percent of 18-hole golf facilities in 2006. Organic sources of nutrients comprise 24 percent of the total annual amount of nutrients applied on 18-hole golf facilities.
For the purposes of this survey, an organic nutrient source was defined as “materials derived from either plant or animal products containing one or more elements (other than carbon, hydrogen, or oxygen) which are essential for plant growth.”
Soil amendments and turfgrass supplements
In 2006, 43 percent of 18-hole facilities did not use soil amendments. The highest use of soil amendments was in the Southwest, where it is common for soil and irrigation water to have high sodium content. A much larger percentage of respondents, 74 percent, use a turfgrass supplement such as biostimulants, humates and amino acids/proteins.
Nutrient management plans
Of 18-hole golf facilities, 49 percent had a written nutrient management plan or written fertilizer plan in 2006, but only 6 percent of facilities were required by government or tribal authorities to have such a plan.
Nationally, only 9 percent of 18-hole golf facilities reported restrictions on fertilizer applications. Restrictions were most likely in the North Central (16 percent) and Pacific (10 percent) agronomic regions. Sixty-two percent of 18-hole golf facilities in the U.S. with restrictions report restrictions on phosphorus – either the total yearly amount applied or the amount per application.
Nutrient application decisions
Superintendents consider multiple factors when making nutrient application decisions. Integrating many variables into their decisions leads to effective applications for turfgrass while protecting the environment. The most common factors superintendents used to make decisions about nutrient applications and the percentage of 18-hole golf facilities using that factor were:
- visual observations of turfgrass (85 percent)
- previous product performance (84 percent)
- soils/soil analysis (84 percent)
- precipitation/ temperature/weather (83 percent)
- turfgrass species (81 percent)
- disease pressure (79 percent)
From 2002 to 2006, 95 percent of 18-hole golf facilities performed soil testing on greens, 75 percent on tees, 80 percent on fairways and 26 percent on rough.
Fertilizer equipment calibration
On average, superintendents at 18-hole golf facilities calibrated their fertilizer application equipment before 67 percent of applications, thereby improving the accuracy of their fertilizer applications. Nationally, 91 percent of 18-hole golf facilities stored fertilizer on site for three consecutive calendar days or more in 2006. Half of those golf facilities used a dedicated storage area.
- GCSAA recommends that all golf facilities use guidelines developed by university scientists to develop written nutrient management plans based on the characteristics and expectations unique to each facility.
- In order to foster sustainability at the golf facility, superintendents should consider the location, climate, and condition of the turfgrass as well as the rate, time of year, and products to be used when making nutrient management decisions.
- GCSAA recommends that superintendents routinely conduct soil tests on the rough, because it receives the greatest total amount of phosphate and potash. Soil testing has the potential to curtail costs and promote fertilizer programs that meet, but do not exceed, the nutritional needs of the turfgrass.
- GCSAA recommends that golf facilities that store fertilizer should use dedicated fertilizer storage areas.
This project is funded by the Environmental Institute for Golf and The Toro Giving Program.