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.