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Fluid Journal : Fluid Journal 1996-1998
1 Fluid Journal Summer 1996 Summary: The objective of this study was to evaluate the response to starter fertilizers of corn hybrids grown in a dryland, no-till production system on a soil high in available phosphorus. Five corn hybrids were treated with or without starters in 1993. The experiment was repeated in 1994, adding a sixth hybrid this time. Starter improved the growth of all hybrids at both the V6 and V1O stages of growth. Both V6 stage whole plant N uptake and P uptake were also improved by the use of starter. Leaf N and P concentrations at silking were higher in all hybrids with starter Starter improved grain yield, improved total P uptake (grain plus stover), and reduced the number of days from emergence to mid-silk in some hybrids but not others. Starter increased the two-year average grain yield of Pioneer 3346 and Dekalb 636 by 15 bu/A. In 1994, starter increased the grain yield of Pioneer 3394 by! 15 bit/A. The yields of ICI 8599 and Pioneer 3563 were not significantly affected by the application of starter. Dryland corn in central Kansas is normally planted as early in the spring as possible. This enables pollination in June when temperatures are more moderate and moisture conditions arc more favorable than in July when conditions are normally hot and dry. Such early-planted corn often shows poorer growth in conservation tillage systems than in conventionally tilled systems. This can be a serious problem with dryland corn planted in early April when soil temperature is less than optimum for plant growth. Cool soil temperatures at planting Drs. W. B. Gordon, D. L. Fjell, and D. A. Whitney Corn Hybrids Vary In Response To Starter Fertilizers Possibility of different rooting characteristics in hybrids prompts this two-year study of selected corn varieties grown under no-till, dryland conditions. time can reduce N and P uptake of corn. Slow plant growth at low soil temperature may be due to limited root growth and reduced nutrient availability. Placing fertilizer in proximity to the seed at planting time has been shown to alleviate the detrimental effects of cool soil temperature on corn growth and development. Though response to such placement has been shown to be positive, studies also show responses to starters can vary among corn varieties. One postulation for such variance is corn hybrids may differ in rooting characteristics and ability to extract and use nutrients. To further explore the behavior of different varieties under the conditions described, we set up experiments in 1993 and 1994 to evaluate the effects of starter fertilizer on corn hybrids with maturities ranging from 2530 to 2850 growing degree units (GDU) grown under no-till. dryland conditions. Table 1. Effect of hybrid and starter fertilizer on total P uptake (grain plus stover) of corn, Gordon, et al., Belleville, KS 1993-94. Hybrid Starter Total P Uptake(lbs/A) 1993 1994 ICI 8599 with 35 40 w/o 35 41 Pioneer 3563 with 39 42 w/o 38 41 Pioneer 3346 with 51 44 w/o 41 40 Dekalb 636 with 44 43 w/o 38 37 Dekalb with 42 45 w/o 37 39 Pioneer 3394 with 48 w/o 43 Interaction Yields up. Starter fertilizer x hybrid interactions for yield, days to mid-silk, and total P uptake were significant for both 1993 and l 994. Starter fertilizers improved yields of some corn hybrids but not others, as shown in Figure 1. Pioneer Brand 3346 yielded 12 bu/A higher with starter than without in 1993 and 19 bu/A higher in 1994. Dekalb Brand 636 yielded 13 bu/A higher with starter than without in 1993 and 18 bu/ A higher in 1994. Pioneer 3394 yielded 15 bu/A higher with starter than without in 1994. Starter had no significant effect on yields of ICI 8599 and Pioneer 3563 both years. Screening. Patterns of corn hybrid response to starters suggest that hybrids can be screened for responsiveness, perhaps using company descriptions of hybrid early-season vigor. Thus, Pioneer 3394 was added to the experiment in 1994 because of the
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