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Fluid Journal : Fluid Journal 1993-1995
3 Fluid Journal Winter 1995 starter rates. High starter rates resulted in better yields and lower grain moisture. High starter rates maintained soil P levels while low rates resulted in soil test P declining below original levels, indicating; that soil fertility was being depleted (Table I ) Right N:P ratio. A cooperative effort between the University of Nebraska and University of Minnesota has shown considerable flexibility exists in the N to P ratio of starters of corn in these states (Table 2). Some treatments were included at seven site- years while others were included at all eleven site-years across the three years (1989-91). Fluid starters were used in a 2 by 2 placement in conservation-till (not no-till or ridge-till) on soils testing low or medium in P. Yields of the no- starter checks ranged from 110 to 174 bu/A with an average of 149 bu/A. The greatest average early-growth enhancement occurred with the 1:1 (N:P2O5) ratio, but the 1:3, 1:2, and 1:1 ratios all had very similar effects and were essentially agronomically equal. The 2:1 and 3:1 ratios produced less early-growth enhancement than the lower N starters. Grain yield increases were similar for all ratios with the possible exception of the 3:1 ratio, which tended to be somewhat less effective. The average yield increase for the four lower N:P ratio starters was 9 percent or 13 bu/A. Proper placement. Fertilizer placement on the seed is a common practice but it holds some pitfalls. It causes stress. It can reduce the number of seeds that germinate or delay germination if conditions are right. Dry soil can exacerbate the situation. Fluid starters applied to one side and below the seed at planting provide a great opportunity to the reduced-till farmer. Unequaled fertilizer efficiency can be achieved. Uptake is increased because starters are in moist soil under the residue. Fixation loss (especially P) is reduced owing to the extremely high concentration of nutrients in a band. Less loss of nutrients means healthier young plants that can better withstand stress. Right source. The debate of "ortho" versus "poly" is less important than application method and timing. Today's high polyphosphates are easy to use and provide quality plant-available nutrients. In addition, the safest fertilizer may not be the most expensive (Table 3). Minimal leaching. Nebraska studies employing isotopically tagged N have demonstrated that use of N from fluid starters can be improved by a nitrification inhibitor. N leaching is curbed as well as nitrification, increasing crop uptake and microbial immobilization of N. The end result: increased yields. Dr. Fixen is North Central director for the Potash & Phosphate Institute, Brookings, SD. ! Table 3. Table 3. ae. Tbl3 Table 3. Conductivity and salt ratios of Conductivity and salt ratios of o uiityndstatio Cndctv a alr sof Conductivity and salt ratios of ro frii Raue vaius etlzers,W. .Rnt various fertilizers, W.R. Raun et various fertilizers, W.R. Raun et various fertilizers, W.R. Raun et .6. al ,198 al ., 1986. al., 1986. al., 1986. Conductivity Conductivity o uctviy Cndit Conductivity C duciviy on tt Conductivity Conductivity Conductivity p U i o er ntf per Unit of per Unit of per Unit of Material Material Material Material mmhos mmhos mm os h mmhos phosphate phosphate pspat hohe phosphate 9-18-9 582 32.3 10-34-0 670 19.7 7-21-7 705 33.6 7-21-7-T* 828 39.4 * Thiosulfate (12-0-0-26) to formulate up to 20 lbs/A salt rate.
Fluid Journal 1996-1998