Sign up for email alerts of new Fluid Journal issues!
Fluid Journal : Fluid Journal 1996-1998
1 Fluid Journal Fall 1996 Summary: Stand reduction of corn ranged as high as 41 to 66 percent, depending on location and materials used, where phosphorus was placed close to corn seeds. The safest liquid material was 10-34-0, followed by 7- 21-7, and 9-18-9. Injury caused by the 9-18-9, which reduced stands significantly was attributed to a larger quantity of N + K20 supplied by this material. In addition to stand reduction, P placed close to the seed also slowed crop emergence. Many farmers in South Dakota plant corn in no-till or very limited tillage situations, thus restricting the application opportunities of a non-mobile nutrient such as phosphorus. Broadcast applications of P have shown reduced effectiveness, especially in drier regions. Subsurface band applications can work but require separate equipment and trips across the field and can cause considerable soil disturbance. Banding phosphorus with the planter, however, has saved time and application costs while placing P below the soil sur-face near plant roots for efficient uptake. While P banded two inches beside and two inches below the seed at planting has been shown to be an effective placement for corn, disadvantages of such placement include: 1) cost of openers, 2) weight, 3) trash clearance, 4) soil disturbance, and 5) possible seed placement difficulties. Because of these problems, many growers in this region are considering placement of phosphorus directly with the seed at planting. Placing P with the seed, however, creates potential for seed injury and reduced stands. One of the objectives of our three- year study (1992-94) was to evaluate the effect of common liquid phosphorus materials on plant emergence when placed directly with corn seeds. Stands reduced As shown in Figure 1, 10-34-0 and 7-21-7 placed in the furrow with corn seed did not reduce emergence below 93 percent, even at the P205 rate of 50 lbs/A. However, in 1994 stands were by Jim Gerwing, Dr. Ron Gelderman and Anthony Bly Effects Of Seed-placed P Studied South Dakota researchers find a number of variables determine tolerance of corn to P placed close to the sed. reduced 41 and 66 percent at Highmore and Beresford, respectively, when the same rate of phosphorus was applied as 9-18-9. The injury caused by 9-18-9 could be attributed to the larger quantity of N + K20 supplied by this material (Table 1). In addition, the N form supplied with the 9-18-9 used here was urea rather than ammonium N supplied by the other two materials. Some ammonia may have been released from the urea N. increasing seed injury. Methodology Sites for this study were located on or near experiment stations at Beresford and Highmore in the southeast and cen-tral parts of South Dakota, respectively. Table 1. Type of fertilizer and rate of nitrogen and potassium applied with phos- phorus, Gerwng, et al. , South Dakota State University, 1994. P2O5 rate ` 10-34-0 7-21-7 9-18-9 lbs/A .................lbs/AN+K2O............ 0 0 0 0 12.5 4 8 12 25.0 7 17 25 50.0 15 33 50 Table 2. Fertilizer and rate used in liquid seed studies, Gerwng, et al., South Dakota State University, 1994. P2O5 rate ` 10-34-0 7-21-7 9-18-9 ....................................... lbs/A............................................. 0 0 0 0 12.5 37 60 69 25.0 73 119 139 50.0 147 238 278
Fluid Journal 1993-1995
Fluid Journal 1999-2001