747-5 Economics of Nitrogen Rate and Application Timing Effects on Wheat.

See more from this Division: S04 Soil Fertility & Plant Nutrition
See more from this Session: Crop Response to Nitrogen Fertilizer

Wednesday, 8 October 2008: 9:45 AM
George R. Brown Convention Center, 360F

Stephen Ebelhar, Crop Sciences, Univ. of Illinois, Urbana-Champaign, Simpson, IL, Emerson D. Nafziger, Univ. of Illinois, Urbana, IL, Eric Adee, University of Illinois-Urbana-Champaign, Little York, IL, Carl Hart, University of Illinois-Urbana-Champaign, Simpson, IL and Lyle Paul, Univ. of Illinois, Urbana-Champaign, Dekalb, IL
Abstract:
The proper rate of spring fertilizer nitrogen (N) application to wheat has taken on a new meaning with the high cost of N fertilizer and the high current price of wheat. Recent N rate and timing of application studies across Illinois have allowed us to determine the optimum economic N rate to apply in the spring to wheat. The spring recommended N rate is based on N price, wheat price and percent soil organic matter (OM). In general, N rates decrease as soil organic matter increases.  This is due primarily to the N released from OM, along with a lower probability of N losses from the higher OM soils. Within an OM level, N rates change as the ratio of N price to wheat price changes. So at the same wheat price, N rates decrease as the price of N increases.  And, at the same N price, N rates move in the same direction as the wheat price. Farmers on low-OM soils who wait to apply their N until later in the spring or split apply their N in the spring with the majority of the N applied just before jointing, are able to gain some N efficiency and should be able to reduce their N rates.  We did not see this same effect on our high-OM sites.

See more from this Division: S04 Soil Fertility & Plant Nutrition
See more from this Session: Crop Response to Nitrogen Fertilizer