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Fluid Journal : Fluid Journal 1993-1995
Winter 1995 Figure 2. Hybrid and starter fertilizer effects on dryland, not-till corn, North Central Experiment Field, Lamond et al., Kansas State University, 1994. No Starter With Starter 230 220 210 200 190 180 170 160 ICI8599 Pioneer Pioneer Dekalb Dekalb Pioneer 3563 3346 636 591 3394 Yield (bu/A) Hybrid the residue (knifed or point injection) produced yields superior to crops receiving broadcast treatments. The point injection system (spoke wheel) achieved a 1.5- to 2- inch depth with less residue disturbance than the knifed applicator. Another study evaluating N rates, sources, placement, and timing on continu- ous ridge-till corn showed similar results with respect to N placement. Knifed UAN performed equal to NH3; however, broad- cast UAN produced lower yields. There was no advantage to splitting UAN application (half knifed at preplant, half at sidedress) compared to knifing all at preplant. Soil was a Crete silt loam. The bottom line in dealing with UAN in conservation-till is to place it in the soil below the residue to minimize any potential for volatilization and immobilization. All hybrids not same Production systems that leave a heavy residue cover on the soil result in cooler and wetter soils, particularly early in the growing season. A dryland corn production system that has gained considerable popularity in Kansas over the past several years involves planting early-maturing (85 to 105 days) corn hybrids from mid-March in southern Kansas to mid-April in northern Kansas. The idea is to get the crop through pollina- tion before extremely hot, dry weather. When this production scheme is employed in no-till systems, there is a high risk of cool, wet soils interfering with N and P uptake of corn. Low soil temperatures result in slow plant growth due to slow root growth and reduced nutrient availability, even though the soil may have high residual fertility levels. Figure 2 summarizes results of two years of work evaluating the effects of starter fertilizer on six corn hybrids ranging from 2530 to 2850 growing degree units. Study sites were dryland, no-till. Soil was a Crete silt loam that had a Bray 1 P level of 85 lbs/A (high range). Hybrids were grown without or with starter fertilizer (30 lbs/A of N and 30 lbs/A of phosphate) as UAN and APP (10- 34-0). Application was two inches to the side and two inches below the seed at planting. N was balanced at 180 lbs/A on all treatments as knifed UAN just after plant- ing. Corn was planted on April 26, 1993 and April 19, 1994. Even though this is just two years of data, results suggest that responses to starter fertilizer can be very economical even on high P soils--at least with some hybrids when corn is planted early in a high-residue production system. This work will be continued and expanded to look at grain sorghum hybrids. Dr. Lamond is professor, Dr. Gordon is assistant professor, and Dr. Fjell is profes- sor in the Department of Agronomy at Kansas State University. !
Fluid Journal 1996-1998