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Fluid Journal : Fluid Journal 1993-1995
1 Fluid Journal Late Spring 1997 Table 1. Influence of N quantity on corn grain and cotton lint yield at alternate furrow expweimental sit, 1991-9192. Crop/Year N rate (lbs/A) Yield/A Corn 1991 0 94 bu 60 119 bu 120 126 bu 180 137 bu Corn 1992 0 94 bu 60 135 bu 120 153 bu 180 157 bu Cotton 1992 0 901 lbs 40 1,259 lbs 80 1,295 lbs 120 1,317 lbs Table 2. Alternate furrow N fertilization irrigation treatments. Water Placement N Placement N Quantity -- lbs/A Corn Cotton Every Furrow Every Furrow 0 0 Alternate Furrow Alternate Furrow 60 40 (non-fertilized) (non-irrigated) 120 80 180 120 Summary: A potential way to improve crop nitrogen (N) use efficiency may be to place furrow irrigation water and nitrogen fertilizer in opposite furrows and therefore not expose fertilizer N to loss pathways associated with irrigation. Research of this "alternate furrow" system in corn and cotton showed that N fertilizer can be placed in alternate fur-rows' (60- inch spacing) without sacrificing crop yield. However, improved N-use efficiency was not noticed. Research was conducted in southeastern Missouri during 1991 and 1992 to evaluate the efficacy of alternate furrow irrigation and applied N fertilizer management systems in corn. A similar study was initiated for cotton in 1992. Surface furrow irrigation is the water delivery system for much of the irrigated corn and cotton produced in the mid- southern United States. Both crops require adequate amounts of N. Corn grown in the mid-South annually receives 120 to 220 lbs/A of N; cot-ton annually receives 60 to 150 lbs/A. Furrow irrigation systems often have poor water use efficiencies, usually because of nonuniform water distribution and percolation. Often, the upper sections of sandy and the lower sections of clayey-textured furrow irrigated fields receive too much water, Improving N-use efficiencies will lead to higher crop yields, better crop quality and reduce the risk of fertilizer N entering undesired or environmentally sensitive niches. Interactions may occur between furrow irrigation water management and fertilizer N effectiveness. The overwatering associated with furrow irrigation may have an antagonistic effect on maintaining a high N-use Dr. Paul W. Tracy and S. G. Hefner More Work Needed on Alternate Furrow N Fertilization Improved N-use efficiency not evident in initial corn/cotton irrigation studies. efficiency. Temperatures during the growing season are warm enough to nitrify most N from ammoniacal based fertilizers within a few weeks of application. Nitrate-N can then be subject to leaching and/or denitrification when excessive amounts of water are added to the soil/plant environment. Water has been conserved with variable yield responses in irrigation systems where only alternate furrows receive water. Lateral water movement and rainfall supply some water to nonirrigated furrows. Soil texture plays an important role in a field's ability to use alternate furrow irrigation effectively. Soils containing high sand content may not permit enough lateral wicking action to supply adequate moisture to nonirrigated rows. Plant roots have shown the ability to obtain the majority of water required from a single irrigated furrow. In Illinois and Idaho research, corn roots have demonstrated a "single sided" ability to obtain crop nutrients without sacrificing grain yield. Alternate furrow placement of N on cotton has not been studied. Sidedressed N in alternate furrows (60 to 80 inches apart, depending on row
Fluid Journal 1996-1998