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Fluid Journal : Fluid Journal 1999-2001
2 Fluid Journal Winter 2000 varying application rates. Data shown will be con-fined to our 1997 experi- ments, but results in 1998 and 1999 showed similar trends. Corn SOP. As can be seen in Figure 1, fluid 7-21-7 starters produced yield increases over check as high as 47 bu/A in soils testing 43 ppm as a Bray-1 P and 380 ppm exchangeable K in the top six inches. Equally evident was the effect fertilizer source, rate of application, and placement method had on corn yields. When the 7-21-7 SOP fluid starter was placed in-furrow with the seed, grain yields were not significantly different from those with fertilizer placed 2 by 2, except at the 200-lb/A rate, where response to in-furrow application was 11 bu/A less than 2 by 2. KCl. Note in Figure 1 how yields were reduced at all KCI starter applica- tion rates when comparing in-furrow with 2 by 2. At 50 lbs/A of fluid 7-21-7, for example, grain yield was reduced 20 bu/A in-furrow compared to 2 by 2 and byasmuchas43bu/Aatthe 200-lb/A rate. Soybeans SOP. As can be seen in Figure 2, fluid 7-21-7 starters produced yield increases over the check as high as 12 bu/A, again in soils high in P and K, and under conditions of varying fertilizer sources, rates and placement methods. Note how yield declined when in- furrow starter application rates exceeded 100 lbs/A, while 2 by 2 placement yield levels remained steady. Below the 100- lb rate, in-furrow yield approximated 2 by 2. KCl. When the 7-21-7 KC1 starter was placed in-furrow with soybean seed, yields were reduced regardless of rate of application. At the 50-lb/A rate, yields were 11 bu/A less when the starter was placed in-furrow compared to 2 by 2. At the 200-lb/A rate, yields in-furrow were 21 bu/A less than those produced by 2 by 2 placement. Salt injury In both corn and soybean experi- ments, in-furrow applications of the 7- 21-7 fluid starter containing SOP resulted in less salt injury than the 7-21- 7 containing KC1. Methodology Soil was a Crete silt loam. Analysis by the KSU Soil Testing Lab showed that in the corn experimental area initial soil ph was 6.4. Organic matter content was 2.4 percent. In the soybean area, pH was 6.5 and organic matter content was 2.2 percent. Supplemental N and S. For the corn experiment, UAN was applied immedi- ately after planting so that all plots received 200 lbs/A of N. Soybeans received no additional N. Sulfur rates were balanced so that all plots received the same amount, regardless of K source. Design was a randomized complete block with three factors. Population. On April 22, corn hybrid Dekalb brand 632 was planted at the rate of 31,000 seeds/A. On May 12, soybean variety Dekalb brand CX37ORR was planted at the rate of 200,000 seeds/A in 30-inch rows. Dr. Gordon is professor North Central Experiment Fields, KSU. !
Fluid Journal 1996-1998
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