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Fluid Journal : Fluid Journal 1999-2001
1 Fluid Journal Fall 2000 Summary: We Summary: We Summary: We Summary: We Summary: We found increased corn yield and increased root pull resistance where nitrogen (N) was placed 2 x 2 and phosphorus (P) was placed in the seed furrow, compared with surface applications. Such results show the importance of precise P and N starter placement for corn production under irrigated, no-till practices and thus support the recommendation that P and N starters be applied in-furrow and banded for optimal corn growth in such systems. However additional potassium (K) fertilizer applications above those recommended by soil tests are not likely to be economically viable. Because our additional K applications did not interact with N and P to increase yields, it is likely that K deficiency problems do not occur under irrigated no-till conditions on high K-testing soils. Under tilled conditions, K applied to soils testing medium to high in K often results in no significant change in corn grain yield. Under no-till conditions, applying N and P directly in the seed row has improved plant growth, crop nutrition, and grain yield. Including fertilizer in the seed row has its risks, of course. It can increase salt concentration surrounding the seed and, under certain circumstances, result in reduced seed germination and crop stand. But even with these potential problems, subsurface application of N and P starters at planting time is a popular practice among many no-till corn producers. The question, then, is what effect, if any, would additional K have on corn yield if applied with N and P under irrigated no-till conditions in soils that have high K soil test values? The influence of K fertilizer rate and placement on yield for corn production in conservation tillage has not been researched extensively. The objective of this research was to evaluate the effects of N and P starters plus additional K applications on corn growth, nutrient composition, and yield in an irrigated no-till field testing very high for K. Our hypothesis was that optimum N and P rate and placement would interact with additional K to Drs. W.E. Riedell, D. L. Beck, and T.E. Schumacher Should K Be Used On High K-Testing Soils? In an irrigated no-till system, South Dakota researchers found K did not interact with N and P to affect corn yield. increase grain yield, shoot mineral nutrient composition, and root pull resistance. Yield Yield Yie d ild Yield Nitrogen/Phosphorus. Subsurface application of P (either with the seed or banded below the soil surface) in conjunction with N banded below the soil surface produced significantly higher grain yield than when N and P were placed on the soil surface (Figure 1). These results agree with other studies showing increased grain yield due to improved P uptake efficiency when N was applied with P in a subsurface band at planting. Subsurface banding of N and P also places fertilizer below the organic -matter-enriched, microbially active residue layer in a region of the soil 161 P with seed N 2x2 Figure 1. Effect of N and P starter placement on corn grain yield, data combined across K fertilizaqtion over 3 years, Riedell, et al., Brookings, SD. P with seed Nonsurface PandN 2x2 PandN on surface 162 163 164 165 166 167 168 Yield-bu/A
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