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Fluid Journal : Fluid Journal 1999-2001
1 Fluid Journal Winter 1999 Summary: In 1993, all iron (Fe) treatments except foliar application produced significant yield increases on both hybrids selected at the 8.6 pH site in North Platte. Most Fe treatments produced significantly higher yields at the 8.2 and 8.6 pH sites but not at the 7.7 pH site. In 1994 and /995, most Fe treatments produced significantly higher yields at the 8.6 pH site. However; the tolerant hybrid selected consistently yielded higher than the non---tolerant. Proper hybrid selection and site-specific treatment on high pH areas with seed row-applied ferrous sulfate (FeSO4•7H2O) can significantly improve corn yields. The advent of variable rate technology and site-specific treatment of problem areas has rekindled interest in corn chlorosis, as well as advances in hybrid selection for tolerance to high pH conditions. The use of site-specific management and variable rate fertilizer application adds a new dimension for the economical correction of Fe chlorosis problems. Soil pH above 8.0 inhibits corn growth by disrupting chlorophyll development and producing interveinal chlorosis. Symptoms range from slight chlorosis to plant death. Prolonged chlorosis delays crop development and maturity, which reduces grain yields and producer profits. Most commercial corn breeding programs in the United States use soils with pH 7 or less, hence selection for tolerance becomes random unless specific high pH screening sites are used. Soil pH between 7.5 and 8 may cause temporary chlorosis and delayed early growth, but the extent of yield effects has not been determined, although chlorosis has been a common problem with many crops. In Nebraska, nearly one million acres of corn are subjected to varying degrees of injury from high soil pH. Most of this acreage is in the western part of the state, but extends into eastern Nebraska in river valley soils. The high pH soil areas do not occur uniformly in fields. This complicates correction because the fertilizer treatment or hybrid selections required to produce the highest crop yields in the problem area may not be best for the remainder of the field. Research with iron chelate on soybeans has produced significant yield increases in Nebraska. However, only limited research has been done with corn. Earlier unpublished research from North Platte suggested that seed- applied acidified ferrous sulfate/sulfide was more effective than banding the material 2 by 2 beside the seed. Application of Fe fertilizers has not been adopted by producers because of the high cost of effective Fe treatment ($20 to $40/A) and/or the loss of specific Fe products from the market. In by G.W. Hergert, Dr. P.T. Nordquist, J.L. Petersen, B.A. Skates Iron For Improved Corn Yield? You bet. Nebraska researchers are showing that under proper ph conditions and hybrid selection, corn yield responds positively to iron applications. addition, no measured soil properties provide a good indication of Fe chlorosis severity. Studies were initiated during 1993 to determine the influence of several seed- applied Fe fertilizers on corn growth, using a tolerant and non-tolerant hybrid selected from previous research. The objective was to determine if any combination of genotypes and/or fertilizer treatments would permit corn yields on high pH soil to approach or equal the performance on lower pH (7.0 to 7.4) soil. Methodology Plot size was individual rows 15 feet long with row width of 30 inches. A factorial design was used, with an untreated check and four replications. In 1993 and 1994, the experiment was established on three sites within one mile of each other. In 1995, only the high pH site was used. Hybrids. In 1993 and 1994, hybrids Pioneer brand 3362 (tolerant to high pH) and Pioneer brand 3398 (non- tolerant to high pH) were selected for the response studies. In 1995, hybrids were changed because the two selected were phased out by Pioneer. Based on other research, the new hybrids selected Table 1. Soil properties (0-8 inches) of three experimental sites, Hergert, et al., University of Nebraska, 1993-1995. SitepHOMPK ZnFeECSAR 1 8.6 17 25 768 0.78 2.9 1.1 0.71 2 8.2 15 16 544 2.35 3.6 0.6 1.24 `37.720335872.618.104.22.168 OM = organic matter; EC = saturated paste extract electrical conductivity (mmho/cm); SAR = sodium absorption ratio.
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