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Submitted to: Journal of Soil and Water Conservation
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 3/11/2019 Publication Date: 11/6/2019 Citation: Balkcom, K.S. 2019. No tillage and non-inversion tillage comparisons across wheat nitrogen rates in Alabama. Journal of Soil and Water Conservation. 74:560-570. https://doi.org/10.2489/jswc.74.6.560. DOI: https://doi.org/10.2489/jswc.74.6.560 Interpretive Summary: Minimizing surface and deep tillage operations for wheat production may promote soil quality, but productivity and N rate requirements need to be examined for these systems across Alabama Coastal Plain soils. An ARS scientist, in Auburn, AL, conducted an experiment to (i) compare non-inversion and no tillage wheat yields and (ii) evaluate N requirements across tillage systems at three locations resulting in nine site-year comparisons. Wheat yields were inconsistent between tillage systems and varied up to 12% at two of the three locations examined, while tillage system had no effect on crude protein and grain nitrogen use efficiency. The greatest N rate applied (134 kg N ha-1) produced yield increases of 17% and 30% greater than the average of the remaining N rates (67 and 101 kg N ha-1) at two of the three locations. No tillage produced 11% greater net returns than non-inversion tillage for one location, while non-inversion tillage produced net returns nearly six times greater than no tillage for the other location. Net returns increased as N rate increased for the two yield responsive sites, but the 101 and 134 kg N ha-1 rates were equivalent. Despite the lack of significance, net returns were nearly double for the 134 kg N ha-1 rate compared to the 101 kg N ha-1 rate at one location. Although no tillage may enhance soil quality benefits, yield increases and net returns were negligible compared to non-inversion tillage across the Coastal Plain of Alabama. Technical Abstract: Minimizing surface and deep tillage operations for wheat (Triticum aestivum L.) production may promote soil quality, but productivity and N rate requirements need to be examined for these systems across Alabama Coastal Plain soils. Experiments were conducted to (i) compare non-inversion and no tillage wheat yields and (ii) evaluate N requirements across tillage systems at three locations resulting in nine site-year comparisons. Each experiment consisted of a split-plot design with tillage as the main plot and six fall and spring applied N fertilizer combinations as subplots, replicated four times. Tiller densities, tiller N concentrations, tiller biomass, wheat yields, grain crude protein, grain nitrogen use efficiency (NUE), and net returns were evaluated. Tillage systems and fall N had no effect on tiller density or tiller N concentrations, except for 8% greater tiller N concentrations for non-inversion tillage compared to no tillage at one location. Non-inversion tillage also produced 23% more tiller biomass compared to no tillage at one location. Wheat yields were inconsistent between tillage systems and varied up to 12% at two of the three locations, while tillage system had no effect on crude protein and NUE measured in the grain. The greatest N rate applied (134 kg N ha-1) produced yield increases of 17% and 30% greater than the average of the remaining N rates (67 and 101 kg N ha-1) at two of the three locations. Net returns corresponded to wheat yields observed at each location. No tillage produced 11% greater net returns than non-inversion tillage for one location, while non-inversion tillage produced net returns nearly six times greater than no tillage for the other location. Net returns increased as N rate increased for the two yield responsive sites, but the 101 and 134 kg N ha-1 rates were equivalent. Despite the lack of significance, net returns were nearly double for the 134 kg N ha-1 rate compared to the 101 kg N ha-1 rate at one location. Results do not support no tillage wheat production across the Coastal Plain of Alabama. |
