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FERTILIZER MANAGEMENT

High-Yielding Corn Response to Applied Phosphorus, Potassium, and Sulfur in Nebraska

^a Agronomy and Horticulture Dep., Univ. of Nebraska, Lincoln, NE
^b IRRI
^c USDA-ARS. Contribution of the University of Nebraska-Lincoln Agricultural Research Division. This research was partly funded by the Hatch Act and the Nebraska State Legislature

^* Corresponding author (cwortmann2{at}unl.edu).

Nutrient management recommendations may change as yield levels and efficiency of crop production increase. Recommendations for P, K, and S were evaluated using results from 34 irrigated corn (Zea mays L.) trials conducted in diverse situations across Nebraska. The mean yield was 14.7 Mg ha^–1 with adequate fertilizer applied. The median harvest index values were 0.52, 0.89, 0.15, and 0.56 for biomass, P, K, and S, respectively. Median grain yields were 372, 49, and 613 kg kg^–1 of aboveground plant uptake of P, K, and S, respectively. The estimated critical Bray-1 P level for corn response to 20 kg P ha^–1 was 20 mg kg^–1 when the previous crop was corn compared with 10 mg kg^–1 when corn followed soybean [Glycine max (L.) Merr.]. Soil test K was generally high with only three site-years <125 mg kg^–1. Over all trials, application of 40 kg K ha^–1 resulted in a 0.2 Mg ha^–1 mean grain yield decrease. Application of 22 kg S ha^–1 did not result in significant yield increase in any trial. Soil test results accounted for twice as much variation in nutrient uptake when soil organic matter (SOM) and pH were considered in addition to the soil test nutrient values. The results indicate a need to revise the current recommendation for P, to maintain the current K and S recommendations, and to use SOM and pH in addition to soil test nutrient values in estimating applied nutrient requirements for irrigated high yield corn production.

Abbreviations: GY, grain yield • HI, harvest index • IE, internal efficiency or grain produced per unit of nutrient in aboveground biomass • RIE, reciprocal of IE, or nutrient uptake require per unit of grain • SOM, soil organic matter • UN-L, University of Nebraska–Lincoln • UP, total phosphorus uptake in the aboveground biomass • UK, total potassium uptake in the aboveground biomass • US, total sulfur uptake in the aboveground biomass

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Received for publication September 19, 2008.