Corn Response to Nitrogen Timing and Rate under Strip Tillage and Low-Yield Environment in Southeastern Coastal Plains
Pawel Wiatrak, Ahmad Khalilian and Guihua Chen
DOI : 10.3844/ajabssp.2011.155.161
American Journal of Agricultural and Biological Sciences
Volume 6, Issue 1
Problem statement: Insufficient rainfall under low yield environment may affect nitrogen management, plant growth indices and grain yields of corn (Zea mays L.). Approach: The objective of this study was to determine the effects of two N application timings (all at planting and as split application with N applied at planting and V6 stage) and five N fertilizer rates (0, 45, 90, 135 and 180 kg N ha−1) on strip-tilled, dryland corn growth and yields under low-yield environmental conditions near Blackville SC, from 2007-2009. Plant growth measurements included plant height, ear height, relative chlorophyll content (SPAD), Leaf Area Index (LAI) and normalized difference vegetation index (NDVI). Results: Plant LAI at V8, NDVI at V8 and R1, SPAD at R1, plant height at V8 and grain yield generally increased with increasing N application rates. Due to most likely insufficient precipitation, the N application timing did not affect corn growth or yield. Despite relatively low grain yields, corn yield was increased by 1.6 Mg ha−1 with increasing N application rate of 100 kg ha−1. Grain yield was positively correlated with plant leaf area index (LAI) at R1 (r = 0.27, p≤0.05) and Normalized Difference Vegetation Index (NDVI) at V8 and R1 (r = 0.33 and 0.29, p≤0.01, respectively) and plant height at V8 stage (r = 0.42, p≤0.001). With N applied at planting, there was a 0.55 and 0.49 Mg ha−1 yield increase with 0.1 increases in plant NDVI at V8 and R1, respectively. Conclusion: Under strip tillage and low yield environment conditions, plant growth and yields may not be affected by timing of N application mainly due to insufficient rainfall. Plant NDVI (for treatments with all N applied at planting) at V8 and R1 can help to estimate potential of corn grain yield, which may be reduced due to low nitrogen use efficiency.
© 2011 Pawel Wiatrak, Ahmad Khalilian and Guihua Chen. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.