Viridescent - the Asian Turfgrass Center blog

How to Save 60% or More in Turfgrass Fertilizer Cost

Some recent events have prompted me to consider fertilizer cost. These include discussions with golf course superintendents, blog posts by Jason Haines in which he describes how he reduced fertilizer costs by 60% and how he can fertilize greens for $25/acre/month, and this advertisement for fertilizer in Thailand, offered at a price of ONLY 38,400 Thai baht per hectare per month (USD $1,243, or about $503 per acre). 

With such a huge (more than 20 times) difference in fertilizer cost, I began to wonder, just what is the cost to get these kind of conditions, as shown in the images in the slideshow below.

The fertilizer used to produce these pictured conditions, for creeping bentgrass, seashore paspalum, and bermudagrass, and also the fertilizer that Jason uses to produce these conditions, is urea and/or ammonium sulfate.

To determine approximately how much nitrogen any turfgrass will use, we can use the temperature-based growth potential. Then, we can apply urea or ammonium sulfate to supply the necessary nitrogen. Phosphorus and potassium should be applied based on the result of a soil nutrient analysis. Let's make a quick calculation of annual fertilizer cost, using the growth potential model for nitrogen and using a typical situation in which soil phosphorus is adequate to meet plant requirements and in which potassium will be applied at half the rate of nitrogen. 

We can consider the cost to apply fertilizer to creeping bentgrass at Osaka. I choose Japan because it has relatively high fertilizer prices. There, the price of urea is ¥2,450 for a 20 kg bag, and potassium sulfate is ¥2,500 for a 20 kg bag. Using the growth potential model, we predict an annual N requirement of 20 g/m², and for K we will apply 10 g/m². Assuming a green surface area of 10,000 m², the annual fertilizer cost for the greens will be ¥81,119. With today's exchange rates, that is equivalent to an annual cost of USD $1,031. And that is a cost of USD $417/acre/year.

At Bangkok, bermudagrass may use about 44 g of N/m²/year, and the urea cost in Thailand is 328 baht for 20 kg. Potassium sulfate is 640 baht for 20 kg and we will apply 22 g K/m²/year. Assuming green surface area of 10,000 m², the annual fertilizer cost for the greens in Thailand, using these products, will be 31,377 baht. With today's exchange rates, that is equivalent to an annual cost of USD $1,016. And that is a cost of USD $411/acre/year. 

With the money spent on the branded fertilizer at ONLY 38,400 baht per month, one could fertilize bentgrass greens at Osaka, or bermudagrass greens at Thailand, for more than a year. That is something to consider when you are choosing which fertilizers to apply.

Handheld or Backpack Sprayer Calibration

A session during a recent seminar at Indonesia was devoted to sprayer calibration, and particular attention was given to the calibration of large, riding sprayers. Backpack sprayers are often used in Asia, and these sprayers also require accurate calibration to avoid misapplications such as we see in this photo.

An excellent guide to hand sprayer calibration is available from Kansas State University, with the four page "Hand Sprayer Calibration Steps Worksheet" available for download. That guide, however, is in imperial units, so I offer this modification to the procedure.

As a general guideline, many products applied through a handheld or backpack sprayer will work best when applied using a spray volume of 40 to 80 mL per square meter. To find the application rate of a handheld sprayer, follow these four steps.
 
1. Measure an area nine square meters in area (3 meters by 3 meters) and mark the edges of this area.

2. Using a stopwatch, measure the amount of time it takes to spray this marked area, using the normal spraying speed and technique.

3. Now, using the same sprayer pressure, spray into a bucket or measuring cup for the same amount of time as it took to spray the nine square meters area. Measure the amount of liquid collected, in mL.

4. To find the spray volume in units of mL per square meter, divide the amount of liquid collected (in mL) by 9. To find the spray volume in units of L/ha, divide the amount of liquid collected (in mL) by 0.9.

Once you have the spray volume, you may decide to adjust the spraying technique so that the amount of liquid applied is in a more suitable range, and you can also determine exactly how much pesticide or fertilizer should be added to the spray tank in order to achieve the desired result.