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Fluid Journal : Fluid Journal 1993-1995
1 Fluid Journal Fall 95 Summary: Although there were no consistent differences in sorghum yields or N-P uptake between surface and subsoil applications in this no-till study on sorghum (1986-87; 1989), we opted in our recommendations for one of the subsurface systems (coulter- nozzle) based on its adaptability and the potential that subsurface applications have for higher fertilizer- use efficiencies. Adequate rainfall was available. Had the trials been curried out under moisture stress conditions, greater differences in yield responses might have been observed. The study was conducted on a Houston Black clay at Temple, Texas. Fluid fertilizers were used in all applications. Conservation farming systems are designed to conserve resources, including the minimization of soil loss by water erosion. Appropriate tillage practices are combined with crop residue cover maintenance to protect soil surfaces from raindrop impact as well as enhance water infiltration. Surface banding of plant nutrients, especially N, may be as effective as subsurface placement if rainfall is adequate. While surface broadcasting of fertilizers may result in the least disruption of residue cover and soil, a number of studies have demonstrated that subsurface banding is the most consistent approach to increased fertilizer-use efficiency in conservation tillage. This practice minimizes contact of nutrients with surface residues (zone of greatest microbial immobilization) and places fertilizer in a soil zone more consistently moist. Initial phases of our work involved the design of an experimental fertilizer applicator and the performance Drs. F.W. Chichester and J.E. Morrison, Jr. Sorghum Yields Similar In Placement Trials Researchers postulate soil moisture level may affect crop response in surface vs. subsurface comparison trials. Grain (bu/A) 90 72 51 36 18 0 1986 1987 No Fertilizer Surface Broadcast Surface Banded Coulter -Nozzle Backswept Knife-Deep No Fertilizer Surface Broadcast Surface Banded Knife Deep Coulter -Nozzle Vee Wheel Yetter Knife Backswept Shallow Application Method 108 90 72 54 36 18 0 Grain (bu/A) 1989 Figure 1. Grain yield response to surface vs. subsuface applications on sorghum, Chichester and Morrison, USDA-ARS, Temple, TX, 1986-87. Figure 2. Grain yield response to surface vs. subsuface applications on sorghum, Chichester and Morrison, USDA-ARS, Temple, TX, 1989.
Fluid Journal 1996-1998