“Our yield goals range from 90 bushels to 300, based on soils’ productive capacity and breakeven analysis of each zone’s maximum economic return,” Rodney says. Goals hinge on profit metrics rather than on the highest yield.  

Variable-rate nitrogen, phosphorus and potassium levels are based on 20 years of detailed farm records and on-farm replicated strip comparisons at various nutrient levels. By varying nitrogen rates by more than 190% as needed, and basing phosphorus and potassium application rates on 20 years’ of home-farm, one-acre grid soil testing data, the Rulons average 181 and 59 bushels per acre corn and soybean yields. They’ve tested on one-acre grids every fourth year since 1992 (five georeferenced probes per acre).

Total applied nitrogen ranges from 115 pounds to 220 pounds per acre, beginning with 30 pounds 28% nitrogen at planting and the rest sidedressed with an Exactrix direct-injection applicator when the corn is knee-high. The whole-farm average is 168 pounds per acre, with an average corn yield of 181 bushels.

They also variable-rate lime and gypsum based on one-acre grid soil test results. A local generating plant provides affordable gypsum as a byproduct that the Rulons use to increase water infiltration, and help lower their clay soils’ high magnesium levels.

Since their application formulas require much less fertilizer than university recommendations, they’ve tissue-sampled growing crops for years to avoid deficiencies.

cost of production