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Fluid Journal : Fall 2010
where broadcast or starter K increased yield by about 10 bu/A compared with the control. A larger response for the Mahaska soil is reasonable because soil test K was borderline between high and very high classes while areas of Taintor tested much higher. The yield response Table 4. Potassium fertilization effects on grain yield for the two dominant soil types in four strip trials where responses differed across soils. No Broadcast K Broadcast K Site Soil Type Soil-Test K NoK Starter K No Starter Starter ppm ----------------Grain Yield (bu/acre)--------------- 1 Zook 236 154a 180b 187b 183b Koszta 213 181 183 179 189 3 Clarion 145 129 132 134 134 Webster 180 138a 135a 151b 149b 5 Floyd 149 196 200 214 210 Tripoli 155 202a 207b 211b 202a 7 Mahaska 214 220a 231b 229b 229b Taintor 268 232 240 233 238 Numbers in a row followed by no letter or a similar letter do not differ (P < 0.10). response to K only for the Webster soil because it is more poorly drained and finer-textured than Clarion. In field 5 the whole-strip analysis did not show a yield response but the analysis by soil type showed a yield response for areas with Tripoli soil. The yield increase was similar for broadcast and starter K, but application of both reduced yield to the control level. The magnitude of the yield increase was even larger for areas of Floyd, although soil test K was similar (optimum) for both soils. Therefore, the statistically significant response only for the Tripoli soil might be explained by a more consistent corn response across the replications. In field 7 the whole-strip analysis did not show a yield response but the analysis by soil type showed a response for areas with Mahaska soil, was higher than expected. But according to previous Iowa research, a response in a high-testing soil can occur with a 5 percent probability. Dr. Mallarino is Professor of Agronomy, Mr. Bergmann was gratuate research assistant, and Dr. Kaiser was postdoctoral research associate, Department of Agronomy, Iowa State University. 15 The Fluid Journal Fall 2010 This article is an adaptation of a paper presented at the 2010 Annual Fluid Forum and also appears in a Proceedings Book made available to attendees of that Forum. MAXIMIZE PROFITS Root Growth Stimulator is a synergistic formulation of zinc and ammonium acetate that stimulates the plant to generate a greater volume of healthier roots. The result is a plant with more vigor and greater stress tolerance that produces higher yields and higher profits. learn more at: www.nulex.com Visit your Nulex Distributor or contact a sales representative at 800-831-4815
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