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Today, temperatures finally began to climb out of the negatives. With the onset of warmer weather, (using this term gently) I felt it was a good time to start looking towards spring. Over the last few months there have been several inquiries regarding lawn fertilization. In response, I have revised the Iowa State University home lawn fertilization publication. Although you will not be pulling out the fertilizer bag for another 4-5 months, I thought I would inspire you with some information that will get you ready for warmer weather. The publication outlines the importance of fertilization, rates and timing of application, label requirements in Iowa, and fertilizer products in the market.

The following is a small excerpt from the introduction.

Lawns are an important component of many home landscapes. Good cultural practices are necessary to achieve a healthy, attractive lawn. One important cultural practice is fertilization. The benefits of a well-maintained lawn fertilization program are good turf color, quality and density. There are 14 elements which are often referred to as mineral nutrient elements and are generally obtaining in the soil via root extraction. The quantity of most of these nutrients contained in the soil is high compared with the requirements of turfgrass plants. However the demands for nitrogen, phosphorus, and potassium oftenexceed the supply in the soil. Thus, it becomes necessary to add these elements through fertilization.

Turfgrasses require nitrogen (N) in the largest amount of any of the essential nutrients. For this reason, nitrogen is usually applied in the largest amounts. Nitrogen nutrition is important to turfgrasses because it canaffect shoot growth and density, root growth, and susceptibility to damage from disease, heat, cold, and drought.

Turfgrasses require potassium (K) in relatively large amounts, second only to nitrogen. Potassium influences turfgrass rooting, disease susceptibility and drought, heat, and cold hardiness. The terms soluble potash, soluble potassium and K₂0 may be used to refer to potassium fertilization. 

Phosphorus (P) is required by turfgrass plants in smaller amounts than nitrogen and potassium. Phosphorus is important in the establishment, rooting, maturation,and reproduction of turfgrasses. The terms available phosphate, available phosphorus, available phosphoric acid, and P₂O₅may be used to refer to phosphorus fertilization. 

The entire extension publication is attached in pdf form.  To download the publication, click on the following link Fertilizer Publication.  

On Friday July 20, 2012, I put up a blog post about some 1988 work that we did with an Iowa lawn care company, All American Turf Beauty, that involved putting lawn care treatments on dormant lawns.  After that post went up, I discussed the possibility of updating the work in the drought of 2012.  The same questions that arose in 1988 from customers worried about damage to their lawns by late-summer applications on dormant lawns are coming up again this year.

All American has changed their program since 1988 and now use granular fertilizer in their July/August treatments at a rate of 0.5 lb. nitrogen (N)/1000 ft².   The fertilizer is an 18-0-4 with 50% slow release N.

We applied the treatments separately to non-irrigated Kentucky bluegrass, tall fescue, and perennial ryegrass areas.  We left an untreated control, and then applied 1 plot at 0.5 lbs N/1000 ft² to one plot, 1.0 lb N/1000 ft², and 2.0 lb N/1000 ft².  We also applied 1.0 lb N/1000 ft²and 2.0 lb N/1000 ft² to separate plots using urea 46-0-0.

There are two questions.  Number 1, will any of the treatments do any harm?  Number 2 which treatments will prove to be beneficial?

The treatments were applied on August 8.  At the research area, we have had 3.4 inches of rain in the last 12 days.  The bluegrass and perennial ryegrass areas are just beginning to show recovery and the tall fescue has nearly recovered.  We had 0.3 inches of rain on the site shortly after treatment.

I will be following these plots over the next few weeks and I will be reporting on the effects of the treatments as the turf further recovers into the fall.

Thanks to All American Turf Beauty for their help with this project.

The next two pictures are of the bluegrass area by the turf building.  It was completely dormant and is just beginning to recover.

The perennial ryegrass is in the foreground and the tall fescue area in the background.  The tall fescue is recovering much faster than the rye.