Progress 07/01/02 to 06/30/03
Outputs
Phosphorus fertilizer management is an important consideration in Western U.S. alfalfa production. The objective of this project was to compare the effects of phosphorus fertilizer sources, rates and placements on irrigated alfalfa yield and tissue phosphorus concentrations. Two field studies were completed in 2001, 2002 and 2003 comparing fluid 10-34-0 and dry 11-52-0 broadcast at two rates (1 X and 1/2 X soil test recommendation). Liquid 10-34-0 was also applied in surface bands with spacings of 15, 30 and 60-cm. Sites responded to phosphorus fertilization in 5 out of 6 site-years, with yield increases ranging from 450 to 3,725 kg/ha (5 to 135%) above the unfertilized control. There were generally few differences in response to band width spacing, though visual indications of band applications were apparent in some plots. In 2003, a single band treatment was applied in the center of each plot. Alfalfa responded to the single band placement as much as 75 cm away from
the band. This indicates that alfalfa was able to access fertilizer placed in bands at the widest spacing of 60 cm in the conventional treatments. Both fluid and dry phosphorus sources were equally effective. Tissue phosphorus concentration responded to phosphorus application, but there were no differences among sources or band spacings. Overall, these results indicate that either dry 11-52-0 or fluid 10-34-0 are effective sources of phosphorus for irrigated alfalfa. Surface banding does not offer any advantage to surface broadcast placements of fluid phosphorus for irrigated alfalfa.
Impacts
Results from this work were incorporated into recent extension fertilizer guides and are being used by soil testing labs and producers to refine fertilizer recommendations for alfalfa in Utah and other western states.
Publications
- Johnson, P.G., R.T. Koenig and K.L Kopp. 2003. Nitrogen, phosphorus and potassium responses and requirements in calcareous sand greens. Agron. J. 95:697-702
- Koenig, R. 2003. Phosphorus sources and placement for irrigated alfalfa: year 2 results. Pp 114-121 in Proceedings of the Fluid Fertilizer Forum, February 16-18, Scottsdale, AZ.
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Progress 01/01/02 to 12/31/02
Outputs
The first two objectives were to compare the effect of phosphorus fertilizer sources, rates and placement on irrigated alfalfa yield. Two field studies were completed in 2002 comparing liquid 10-34-0 and dry 0-45-0 broadcast at two rates. Liquid 10-34-0 was also applied in surface bands with spacings of 15, 30 and 60 cm. Yields were lower than normal due to drought and results mixed between the two sites. Both sites responded to phosphorus fertilization, with yield increases ranging from 450 to 1,344 kg/ha (5 to 21%) above the unfertilized control. At one site, the 24 inch band spacing yielded 550 to 825 kg/ha more than the 30 or 30 cm spacings. Tissue phosphorus concentration responded to phosphorus application, but there were no differences among sources or band spacings. The next objective was to compare the effect of S sources and rates on the yield, quality, and soil and tissue sulfur concentrations in established alfalfa. Five sulfur sources were applied at
three rates to established alfalfa. Yield ranged from 7.2 to 9.0 Mg/ha at the first location and 5.8 to 7.2 Mg/ha at the second. Yields at both locations were lower than normal due to drought and frost. Averaged over sulfur sources, yield was increased by 1,120 kg/ha (16 to 19%) above the control with the 56 to 112 kg sulfur/ha rate at both sites. There were few differences among sulfur sources. Sulfur fertilization did increase soil and tissue test sulfur concentrations but did not affect alfalfa forage quality. Both studies indicate a potential to significantly increase alfalfa yield with appropriate phosphorus and sulfur source and rate management.
Impacts
Results from this work were incorporated into recent extension fertilizer guides and are being used by soil testing labs and producers to refine fertilizer recommendations for alfalfa in Utah and other western states.
Publications
- Koenig, R., M. Nelson, D. Miner and J. Barnhill. 2002. Fertilizer management for grass and grass-legume mixtures. Utah State University Extension electronic publication AG-FG-03. 5pp.
- Drost, D., R. Koenig and T. Tindall. 2002. Nitrogen use efficiency and onion yield increased with a polymer-coated nitrogen source. HortScience 37:338-342.
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