OLCA Research

Introduction
One of the most critical things that we do in turfgrass management is to fertilize the turf to maintain a healthy sward and to prepare the turf so that is can withstand traffic and recuperate from it. It is the role of the turf manager to determine turf fertilizer needs based on annual soil tests and by having a clear understanding of how fertilizers work.
In addition to understanding the complexities of fertilizer types, rates and timings, turf managers may also be working with products in the future that do not contain phosphorus. The decision to take phosphorus out of turf fertilizer is one that is multifaceted. Economics plays a role, but unfortunately, misplaced fear of phosphates ending up in water is also a driving force. Phosphorus is tightly fixed onto soil particles and does not leach from native soils unless the soil somehow  moves into a drain or river or lake. A healthy lawn does not leach phosphorus into water. In fact, the best way to prevent soil erosion from turf is to keep it fed!

Regardless of the facts, these decisions are being made and the turfgrass manager will need to be prepared to manage turf without phosphorus.

Another trend in fertilizer management is the desire of some homeowners and public facility administration to move away from synthetic fertilizers in favor of natural fertilizers. Natural fertilizers are derived from a natural source like manure or compost (so they can be odiferous) and they typically do not have nitrogen contents higher than 8%. Natural fertilizers cost more money per lb. of nitrogen than synthetic sources and they are reliant upon soil temperatures for release. Still, there is a belief that natural sources not only feed the turf, but that they can improve the soil health in a turfgrass system. Natural fertilizers that contain organic material may help to improve a soil’s bulk density and nutrient status overtime, which will be monitored in this study.

Objectives: 

To compare the quality response of “Kenblue” Kentucky bluegrass (Poa Pratensis) following the application of fertilizer with various nitrogen (N) sources and to monitor soil chemical and physical changes over time.

Materials & Methods: 

Mature Kentucky bluegrass turf maintained at 3” height with a rotary mower and clippings returned. 

Native soil characteristics, determined by CLC Labs at the beginning of the study were as follows:
Soil texture is a clay loam/clay (27% sand, 33% silt, 40% clay)
pH 7.7
Soil organic matter 3.9% (low-medium)
P, K, Ca, and Mg all in the sufficient range.
CEC 21.5 (medium range)
Other results: Tissue Nitrogen 2.4% (low range)
Irrigation was applied to maintain healthy turf.  Plots in a randomized complete block design, replicated three times.
Fertilizer treatments were applied at a rate of 1 lb nitrogen/1,000 ft-2.  Applications were made every eight weeks on the following dates: May 7th, July 6th, August 31st and end of October, 2009.

Treatments:
1.  Urea 46-0-0
2.  Lesco 21-4-11
3.  Ecosential 5-2-4
4.  Nature Safe 10-2-8
5.  Nature’s Helper 2-1-1
6.  Spring Valley Professional 20-2-5 7. 
7.  Sustane 5-2-10
8.  Milorganite 5-2-0
9.  Corn Gluten Meal 10-0-0 (Figure 1)
10. Comtil Plus  3-2-1
11. Advanced Turf Solutions (ATS) 22-3-11
12. ATS 22-0-5
13. Andersons 37-0-0
14. Untreated

Figure 1: Corn Gluten Meal is a natural fertilizer that contains herbicidal properties.

Measurements:
•    Quality: Visual quality (color and density) is rated on a scale of 1-9, with 1 representing poorest and 9 representing best.  The visual assessment is based  on NTEP Guidelines (www.ntep.org ) and is performed every two weeks. Preliminary results for 2009 can be seen in Table 1.

•    Macro Nutrient Deficiencies? Some of the fertilizers do not contain all of the macro nutrients P or K needed for sustained turf growth, so it will be interesting to see what effects no P or K has on the quality of the turf over time.

•    Soil changes over time, including: Organic matter content, pH, cation exchange capacity, and available nutrients. Soil samples will be sent to CLC Labs at the end of the growing season in 2009.

•    Economics. The study will address cost of nitrogen source and turf quality.  For example, corn gluten meal costs $4.50/lb N versus $1.25/lb N for urea, but factors to consider include soil health and turf quality obtained by these nitrogen sources over time.