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Fluid Journal : Fluid Journal 1999-2001
2 Fluid Journal Winter 1999 were: Pioneer brand 3279 (somewhat tolerant to Fe chlorosis) and Pioneer brand 3489 (sensitive to Fe chlorosis). Applications. The plot areas received 180 lbs/A of N as a preplant application in mid-April. In 1993 and 1994, a ridge-till planter was run through the areas prior to planting to block out row locations, and apply a band of 10-34-0 + 1% Zn at the rate of 10 gal/A to the side of the future seed location. In 1995, a new two-row planter was used that placed Fe fertilizer directly in the seed furrow during planting and applied 10-34-0 + 1% Zn two inches to the side of the seed. In 1993 and 1994, two foliar sprays of 1.5% FeSO4•7H2O, plus 5 lbs/A urea- N, were applied directly over the corn row in mid-June and early July at the rate of 20 gal/A at 20 psi. In 1995, one foliar spray of 1.5% FeSO4•7H2O, plus 5 lbs/A urea-N, was applied directly over the corn row in late June at the rate of 20 gal/A at 20 psi. Planting. Corn was planted two inches deep in early May each year, using a 7-inch seed spacing. Soil. The studies were conducted on soils ranging in pH from 7.7 to 8.6 (Table 1). Soil at the high pH site is classified as Cozad silt loam, saline- alkali and has thin bands of very high pH (>8.5) within the root zone. Soils at the calcareous and non-calcareous sites are both Cozad silt loam. Site problems Chlorosis. Significant growth differ-ences and plant population effects among Fe treatments and hybrids were evident in 1993 and 1994 due to severe chlorosis on one high pH site, but not on the other two sites. On the high pH site, plant popula-tion of the non-tolerant hybrid was signif-icantly lower than the tolerant variety due to plant death (data not shown). Hail storms. A hail storm in late July 1993 damaged the crop on the high pH plot (Site 1), which limited yield potential. In 1994, Site 1 was hit by hail when plants were 8 inches tall (early June) and had some further hail damage in late July. Sites 2 and 3 had Figure 1. Effect of Fe source on grain yields of corn at Site 1, pH 8.6, Hergert, et al. , University of Nebraska, 1993-1995. Figure 2. Effect of Fe source on grain yields of corn at Site 2, pH 8.2, Hergert, et al. , University of Nebraska, 1993-1994. 20 TNTTNTTNT T T T T T T NTNTNT NTNTNT 1993 1994 1995 40 60 80 100 120 140 160 180 Yield-bu/A Check Foliar Fe Fe So4 T=Tolerant Hybrid NT = Non-tolerant Hybrid 80 TNTTNTT T T T NT NT NT NT 1993 1994 100 120 140 160 180 200 Check Foliar Fe NT = Non-tolerant Hybrid Fe SO4 T= Tolerant Hybrid Yield-bu/A
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