358-2 Improving Nitrogen Recommendations for Winter Wheat In Arkansas.



Wednesday, October 19, 2011: 8:20 AM
Henry Gonzalez Convention Center, Room 211, Concourse Level

Trenton Roberts1, Nathan Slaton2, Richard Norman2 and Jason Kelley3, (1)Crop, Soil, and Environmental Sciences, University of Arkansas, Fayetteville, AR
(2)University of Arkansas, Fayetteville, AR
(3)Crops, Soils and Environmental Science, University of Arkansas Division of Agriculture Extension, Little Rock, AR
The recent success of N-ST*R- the N soil test for rice has led to the development of a soil-based N test for winter wheat in Arkansas. Current N rate recommendations for winter wheat in Arkansas are based on a combination of soil texture and previous crop. During the past five years N rate trials have been conducted on silt loam soils across the state of Arkansas to determine the ability of alkaline hydrolyzable- N (AH-N) to correlate with wheat TN uptake, percent relative grain yield (RGY) and calibration of AH-N to predict N needs for wheat. Soils were sampled in 15 cm increments to 60 cm and analyzed for AH-N by either the Illinois Soil N Test (ISNT) or Direct Steam Distillation (DSD).  Wheat TN uptake was highly correlated (>0.68, p<.001) with both the ISNT and DSD at the 0-15 cm depth, indicating the relationship between AH-N and plant available N were closely linked. Results also exhibited a strong correlation between percent relative grain yield and ISNT and DSD at the 0-15 cm depth. Calibration of N rate to achieve 95% RGY at the 0-15 cm depth, resulted in a coefficient of determination >0.75 for both methods. The results of this work are the first step in developing site-specific N fertilizer rate recommendations for winter wheat, and will help to improve the long-term sustainability of Arkansas winter wheat production.
See more from this Division: S04 Soil Fertility & Plant Nutrition
See more from this Session: Site Specific Nutrient Management: I