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Fluid Journal : Fluid Journal 1999-2001
2 Fluid Journal Fall 2001 season was the warmest and driest since 1934, yields were much below the long- term average. Dribblevs2x2 Although surface dribble-applied starter fertilizer increased grain yield over the no-starter check, yields were greater when fertilizer was placed 2 x 2 (Figures 1 and 2). When averaged over tillage and starter combinations, yields were 9 bu/ A greater when starter was placed subsurface as compared to surface dribble (Figure 3). However, when averaged over two years of the experi- ment, 90 percent of maximum yield was achieved with dribble-applied starters. At the V6 stage, whole-plant concentra- tions of N and P were greater when fertilizer was placed 2 x 2 rather than dribbled on the soil surface. Early- season differences in nutrient uptake between starter application methods were still present at later growth stages. Leaf tissue concentrations of N and P at early bloom were greater when starter fertilizer was applied 2 x 2 compared to surface dribble applications. Minimum vs no-till While grain yields, days from emer- gence to mid-bloom, and plant tissue nutrient concentrations were not affected by tillage system, the use of starters did increase yields in either system. The greatest yields occurred with 2 x 2 applications of starter fertilizer containing either 30 or 45 lbs/A of N in combination with P (Figures 1 and 2). The higher N starters were also the most efficient in reducing the number of days from emergence to mid-bloom (Figure 4). Early-season dry matter yield was the one tillage exception, being greater in the minimum-till system than the no- till system. Solo vs combo The N-alone or P-alone treatments did not yield as well as starters that con- tained both N and P The treatment containing only 15 lbs/A of N with 30 lbs/A of P2O5 was not as effective as starters containing more N. Methodology Location. The experiment was conducted at the North Central Kansas Experiment Field. Soil was a Crete silt loam with an initial pH of 6.2, organic matter at 2.2 percent, Bray-I P at 42 ppm, and exchangeable K at 320 ppm in the top 6 inches of soil. Cultivation. The minimum-till system was disked and harrowed once in the spring three weeks prior to planting. Fertilizer. Starter combinations were made by using liquid ammonium polyphosphate (10-34-0) and 28 percent UAN. The treatment receiving 30 lbs/A of P2O5 applied alone was made by using laboratory grade phosphoric acid. Placement. At planting, starter was placed either 2 inches to the side and 2 inches below the seed or dribbled in a band on the soil 2 inches to the side of the seed row. Application rate. Starters consisting of N and P2O5 combinations were applied at the rate of 15, 30 or 45 lbs/A of N with 30 lbs/A of P2O5 , Also included were treatments consisting of either 30 lbs/A of N or 30 lbs/A of P2O5 applied alone, and a no-starter check. After planting but before emergence, knife applications of 28 percent UAN were made to bring N applied to each plot to a total of 140 lbs/A. Seeding. Grain sorghum (NC+7R83) was planted at the rate of 60,000 seeds/ A on May 17, 2000. Dr. Gordon is professor at the North Central Kansas Experimental Fields, KSU, and Dr. Whitney is professor of Extension Agronomy, KSU. ! 113 111 109 107 105 103 101 99 97 Figure 3. Means for grain yield as affected by tillage and fertilizer placement at Belleville, Gordon, et al. , 1999-2000. MINIMUM TILL NO TILL DRIBBLE 2x2 YIELD - bu/A 114 111 108 105 102 99 96 93 90 80 70 60 50 40 30 20 10 0 Figure 4. Means for grain yield and days to mid-bloom as affected by starter composition at Belleville, Gordon, et al. , 1999-2000. DAYS TO MID-BLOOM DAYS TO MID-BLOOM YIELD N/P O - LBS/A 25 YIELD - bu/A 0-30 30-0 15-30 30-30 45-30
Fluid Journal 1996-1998
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