Nitrogen applications for wheat production across tillage systems in Alabama

Authors: Balkcom, Kipling; BURMESTER, CHARLES - Auburn University

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/19/2014
Publication Date: 2/25/2015
Publication URL: http://handle.nal.usda.gov/10113/62404
Citation: Balkcom, K.S., Burmester, C. 2015. Nitrogen applications for wheat production across tillage systems in Alabama. Agronomy Journal. 107:425-434.

Interpretive Summary: Alabama wheat farmers are changing management practices, which include using higher nitrogen (N) fertilizer rates and planting wheat with no-tillage or reduced tillage systems to maximize yields. ARS researchers at the National Soil Dynamics Laboratory in Auburn, AL in cooperation with scientists from Auburn University conducted experiments over three years at multiple locations throughout Alabama to (1) determine the level of tillage necessary to optimize wheat yields across different regions of Alabama and (2) determine if N requirements change across tillage systems and regions. Conservation tillage including non-inversion tillage on the Coastal Plain soils and no-tillage on the Limestone Valley soils produced equivalent or superior yields to multiple pass conventional tillage operations. Fall N and applying total N by mid-Feb. was imperative for successful wheat production on Coastal Plain soils, while Limestone Valley soils were less responsive to applied N. These results indicate that conservation tillage techniques that save time, fuel, and labor, while promoting soil health can be successfully used with current N recommendations for wheat across Alabama.

Technical Abstract: Alabama wheat (Triticum aestivum L.) farmers are changing management practices, which include using higher nitrogen (N) fertilizer rates and planting wheat with no-tillage or reduced tillage systems to maximize yields. Experiments were conducted to (1) determine the level of tillage necessary to optimize wheat yields across different regions of Alabama and (2) determine if N requirements change across tillage systems and regions in Alabama at four locations resulting in nine site-year comparisons. Each experiment consisted of a split-plot design with tillage as the main plot and twelve N fertilizer treatments as subplots, replicated four times to compare Zadoks’ Growth Stage (GS)-30 tiller densities, tiller N concentrations, tiller biomass, GS-31 wheat biomass, biomass N concentration, wheat yields, and grain crude protein. Nitrogen treatments consisted of different rates across fall, GS-30, and GS-31 application times. Tillage systems had no effect on tiller density, tiller N concentration, or tiller biomass, but fall N increased tiller density 15% and tiller biomass 34% across Coastal Plain locations. Non-inversion tillage increased wheat yields 13% on Coastal Plain soils compared to conventional tillage. Fall N increased wheat yields 10%, and N applied at GS-30 improved yields 18% compared to delaying application until GS-31, indicating application of fall N and applying total N by GS-30 was imperative for successful wheat production on Coastal Plain soils. Neither tillage system nor N applications affected wheat production extensively across the Limestone Valley. Non-inversion tillage or no-tillage with current recommended N practices can be successfully used in Alabama wheat production.