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Fluid Journal : Fluid Journal 1999-2001
2 Fluid Journal Fall 2001 addition, the analytical procedure (tur- bidimetric method) may not be appro- priate for these soils for SO4-S determi- nation. More work on this aspect of soil- available SO4-S is forthcoming. Corn response To sulfur. Grain yield increased sig- nificantly for the S treatment compared to control (146.5 bu/A vs. 127.3 bu/A) when pooling landscape positions (Fig- ure 1). To landscape position. Overall grain yield increased substantially from the shoulder to the footslope from a mean of 113.4 to 160.8 bu/A. Soils at the footslope provide a favorable growing environment because of more favorable chemical and physical properties and soil water status compared to the eroded soils at the shoulder positions. There were many agronomic factors contribut- ing to yield decreases as yield sampling progressed upslope. If S is a limiting nutrient to corn grain production due to landscape position, then an S application should be more effective when applied to soils at the shoulder position. Comparing the con- trol to the single S application to land- scape position (Figure 2), S signifi- cantly increased corn grain yield for the shoulder (103.1 bu/A vs. 128.5 bu/A) and backslope positions (119.4 bu/A vs. 150.6 bu/A). There was no signifi- 100 CONTROL ATS SHOULDER BACKSLOPE FOOTSLOPE 110 120 130 140 150 160 170 180 YIELD - BU/A Figure 1. Corn grain yield response for treatmants and landscape positions, ATS @ 25 lbs/A, Woodard and Bly, Garretson, SD, 2000. 100 CONTROL ATS CONTROL ATS CONTROL ATS YEILD - BU/A SHOULDER BACKSLOPE FOOTSLOPE 180 110 120 130 140 150 160 170 Figure 2. Mean corn yield responses to ATS on landscape positions, ATS @ 25 lbs/A, Woodard and Bly, Garretson, SD, 2000. cant grain yield response to S on the footslope where the topsoil was 24-36 inches in depth. Visual symptoms. Visual symptoms are not the best indicator of the occur- rence of S deficiencies. Sometimes the leaf-striping symptoms may be stronger in one season than in another. They could dissipate somewhat or intensify as the growing season progresses. The onset of leaf-striping may also occur at different growth stages. Mild onset of leaf striping may not be alleviated very much by S applications. Plant tissue analysis is the best indicator for S defi- ciencies and S response potential. M t ology e hod ogy Methodology Methodology Methodology Field site was near Garretson, South Dakota. The site has an extensive his- tory without tillage and a rolling land- scape---different from the site chosen in 1999. Fertilizers. Two tanks contained UAN. One tank contained the ATS, which was applied 5 inches from the planted row. Another two tanks con- tained starter (7-21-7), some of which was applied with the seed. S placement. ATS was applied at a two-inch depth by five-inch wide con- figuration with respect to seed place- ment. Planting. Corn (DeKalb DK 477) was planted at a population of 26,500 seeds/A on May 3. Plots. Corn plots 15 feet wide by 40 feet long were established on the shoul- der, backslope, or footslope positions. Fertilizer rate/A. S was applied as ATS at rates as shown in Table 1. In- cluded in the table are rates/A for N, P, and K. Dr. Woodard is professor of Soil Fertil- ity and Crop Nutrition and Bly is a re- search associate in the Plant Science Department at South Dakota State Uni- versity in Brookings, South Dakota.
Fluid Journal 1996-1998
Fluid Journal 2002-2004