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How much fertilizer can I afford?
Stacy Campbell
Stacy Campbell

In crop production we know that fertilizer is an important part of producing a good crop. We also know that it can be an expensive part of that crop production bill. Depending on the crop it can be 20 to nearly 50% of direct costs and 15-30% of total costs. This year it may be even higher. Compared to late last summer, fertilizer prices have risen steeply. Increases have ranged from 100% to over 200% depending on the type of fertilizer. (Homeowners and gardeners need to be prepared to see higher prices for their fertilizers also). While prices may have moderated slightly in recent weeks, we are still looking at fertilizer costs that may be nearly double what they were last year.

The first instinct for many is to blindly cut fertilizer application rates. While reducing application rates will definitely reduce how much you spend, it can also increase the cost per bushel as yields may very well drop. We are dealing with an economics principle known as the law of diminishing returns. The biggest response comes from the first pound of fertilizer applied. As you add more fertilizer the yield increases and the cost of production, per bushel, goes down, up to a point. You then get to the point where additional fertilizer doesn’t increase gain enough to justify the expense and cost per bushel starts to go back up. All of these factors depend on price of the fertilizer applied and value of the product produced. 

As you make your fertility plans for any crop production this year, it is important not to make a knee jerk reaction on cutting fertilizer rates. Start with a good soil test so we can properly account for the nutrients that you already have in your fields. Some years I might encourage you to build soil nutrient levels for nutrients like phosphorus (P). This is not one of those years. 

However, if you have been building P in your soil profile and have 20> ppm in the 0-6 inch soil profile. This is the year you could reap the benefits. By significantly cutting back P based on your yield goal.   

Once we know what’s in the soil, we can determine a cost appropriate fertilizer application rate that won’t break the bank, hopefully. High prices do not negate the plant’s biological need for proper nutrient levels for good growth and decent yields. Now is not the time of making irrational decisions. Now is the time to approach crop production with a keen management mind to get the best return on your dollar!

If you have any questions or need to utilize our soil sampling probes to take your own soil samples--give us a call or drop by the Cottonwood District Offices in Hays and Great Bend. 


Stacy Campbell is an Agriculture and Natural Resources agent for Cottonwood Extension District. Email him at scampbel@ksu.edu or call the Hays office, 785-628-9430.