Effects of No-tillage and Improved Fertilizer Management on Corn Yield and Soil N2O Emission in Middle Tennessee

Monday, July 28, 2014
Ballroom A/B/C (Rosen Plaza Hotel)
Qi Deng , College of Agriculture, Human and Natural Sciences, Tennessee State University, Nashville, TN
Dafeng Hui , Tennessee State University, Nashville, TN
Junming Wang , Center of Atmospheric Science, Illinois State Water Survey, University of Illinois at Urbana-Champaign, Champaign, IL
Tigist Jima , College of Agriculture, Human and Natural Sciences, Tennessee State University, Nashville, TN
Stephen Iwuozo , College of Agriculture, Human and Natural Sciences, Tennessee State University, Nashville, TN
Chih-Li Yu , College of Agriculture, Human and Natural Sciences, Tennessee State University, Nashville, TN
David Smart , University of California, Davis, CA
Suping Zhou , Agricultural Sciences, College of Agriculture, Human and Natural Science, Tennessee State Universitsy, Nashville, TN
Chandra Reddy , College of Agriculture, Human and Natural Sciences, Tennessee State University, Nashville, TN
Sam Dennis , College of Agriculture, Human and Natural Sciences, Tennessee State University, Nashville, TN
While the use of no-tillage and improved fertilizer management are proposed as effective ways to enhance corn yield and reduce greenhouse gas emission, their effects remain controversial and the related influencing factors are not well understood. We conducted a field experiment to study the responses of corn yield and N2O emission to various management practices in middle Tennessee. The management practices include no-tillage + regular applications of urea ammonium nitrate (NT-urea); no-tillage + regular applications of urea + denitrification inhibitor (NT-inhibitor); no-tillage + regular applications of urea + biochar (NT-biochar); no-tillage + 20% applications of urea + chicken litter (NT-litter), no-tillage + split applications of urea (NT-split); and conventional tillage + regular applications of urea as a control (CT-urea). Fertilizer equivalent to 217 kg N ha−1 was applied to each of the experimental plots. The experiment used a randomized complete block design with six replications. Results showed that fertilizer management had no significantly effect on corn yield. However, no-tillage (NT-urea) significantly increased corn yield —by 47%—over the conventional tillage (CT-urea). Corn yield tends to be positively related to water filled pore space (WFPS) and negatively related to soil inorganic N (NH4+-N and NO3--N) across all treatments. Soil N2O emission was significantly influenced by no-tillage and fertilizer management. The highest cumulative N2O release from soil occurred in the CT-urea (20.55 kg N2O ha-1), which was significantly higher than those in the NT-urea (12.92 kg N2O ha-1) and NT-litter (12.31 kg N2O ha-1) treatments, and much higher than those in the NT-inhibitor (6.85 kg N2O ha-1), NT-biochar (4.25 kg N2O ha-1) and NT-split (8.66 kg N2O ha-1) treatments. Significant exponential relationships between N2O emission rate and WFPS were detected in all treatments. Variation in N2O emission among the treatments was positively correlated with its moisture sensitivity. The emission of N2O at yield scale showed similar patterns as the N2O emission. It was the highest in the CT-urea (2.51 kg N2O ton-1), relatively low in the NT-inhibitor (1.00 kg N2O ton-1) and NT-biochar (0.87 kg N2O ton-1), and intermediate in the NT-split (1.47 kg N2O ton-1), NT-urea (1.97 kg N2O ton-1) and NT-litter (1.47 kg N2O ton-1) treatments. Our results indicated that the use of no-tillage and improved fertilizer management could enhance corn yield due to soil water conservation, reduce N2O emission by decreasing its moisture sensitivity, and ultimately reduce yield-scaled N2O emission.
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