As corn and soybean farmers prepare for harvest, it’s not a bad idea to start mapping out a fall fertilizer plan, says Dennis Bowman, Extension educator for commercial agriculture, University of Illinois. For one thing, purchasing nutrients now could save money down the road.
"The wholesale prices of fertilizer have dropped quite a bit," Bowman says. "They’re about the lowest they’ve been in two years."
Before placing an order, review these four steps to make sure the fertilizer you buy will help maximize profitability in the year ahead.
1. Calculate your fertilizer needs
Beyond monetary costs, farmers should avoid yield penalties in 2014 by using a couple of tools to evaluate how much fertilizer they’ll need to apply this fall.
To determine nitrogen needs, Bowman recommends using a state-level Maximum Return to N (MRTN) calculator. The University of Illinois is one of several universities that offer an online calculator farmers can use to tabulate nitrogen requirements based on local nitrogen research data and current prices.
To determine lime, phosphorus and potassium needs, soil tests are key. These should generally be taken right after harvest and in about the same timeframe as soil tests taken in previous years.
"There is a little bit of a cycle in how soils test," Bowman says.
In general, soils within a field fall into one of three categories. Soil below the appropriate nutrient threshold might need a buildup program to restock. Other soil might be at a maintenance level, meaning it needs fertilizer simply to compensate for nutrients removed by crops during the growing season. A third category of soil might need a drawdown program, meaning fertilizing is withheld for one or two years, allowing excess nutrients to be used up.
While many Midwest farmers used to apply 200 lb. per acre of diammonium phosphate (DAP) and an equal volume of potash, the use of calculators and soil tests has become the preferred method for determining needs to maximize efficiency and limit cost.
2. Wait for cool soil temperatures