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Fluid Journal : Fluid Journal 1993-1995
1 Fluid Journal Fall 1995 n conservation tillage environments where below-optimum soil temperatures lower nutrient availability, starter fertilizers can place nutrients within the rooting zone of young seedlings for improved availability. In some experiments that have evaluated crop response to NP starters, improved early growth and increased yield were attributed to the P component of the combination. In others, N has been indicated as the most critical element in soils not low in P. A common practice in the central Great by Drs. W.B. Gordon and D.A. Whitney I Star Star Star Star Starters Bump Sorghum Y ters Bump Sorghum Y ters Bump Sorghum Y ters Bump Sorghum Y ters Bump Sorghum Yields 18 ields 18 ields 18 ields 18 ields 18 PPPPPerc ent ercent ercent ercent ercent Kansas researchers also find fluid starters applied at right N:P ratio improve early- season growth and hasten maturity. Summary: Use of starter fertilizers has become common in conservation tillage corn, hut little attention has been given to starter nutrient ratios for no-tilled grain sorghum. We therefore initiated field research from 1991 through 1993 in North Central Kansas to evaluate the effect of different N:P starter ratios on grain sorghum production. Averaged over three years of the study, starter combinations providing either a 1:1 or 3:1 N:P2O5 ratio shortened the time from emergence to mid-bloom and increased yield by 18 percent over our 3:1 N:P2O5 ratio broadcast check. These yield increases were consistent for the two different planting dates we established. Results demonstrated that early-season growth and yield can be improved with a 1:1 or 3:1 N:P2O5 ratio versus the 1:3 (10 lbs/A of N with 30 lbs/A of phosphate) N:P2O5 ratio commonly used to grow grain sorghum in the central Great Plains. Plains is to apply starter in an N:P ratio of approximately 1:3 (10-34-0 liquid) at a rate of approximately 100 lbs/A. Some grain sorghum producers in the central Great Plains prefer to delay planting until mid-June to avoid drought and heat stress during the crop's reproductive phase of development (July and early August). However, late planting increases the risk of an early frost occurring before crop maturity. Starters can hasten maturity and avoid late-season low temperature damage. Yields bu/A 100 90 80 70 60 50 50 50 40 30 20 10 0 10N 30P 30N 30P 90N 30P 90N noP 30N noP noN 30P 90N 30P Broadcast N:P O ration 25 Figure 1. Effect of starter N:P O ratio on grain sorghum yield, Gordon and Whitney, Kansas State University, average. Of 1991-93 25 Table 1. Growing season rainfall at Belleville, Kansas. Year Month 1991 1992 1993 30-yr. avg. April 3.07 1.57 2.58 2.47 May 3.90 2.18 3.21 4.07 June 3.17 4.73 4.61 4.31 July 0.74 8.63 17.89 3.86 August 1.78 3.64 4.79 3.78 September 0.81 3.22 2.44 3.37 October 0.74 4.95 1.14 2.19 Total 14.21 28.92 36.66 24.05 in.
Fluid Journal 1996-1998