Beef

Effects of Season and Soil Available Phosphorus Content on the Phosphorus Concentration of the Forage in Cool-Season Grass Pastures of Southeastern Iowa

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Abstract

A 5-month study was conducted to evaluate the relationship between soil available phosphorus (P) and forage P concentrations in May, July, and September 2011. Four cool-season pastures were sampled at the Iowa State University McNay Research Farm near Chariton, Iowa. Forage samples were hand-clipped to ground level from a 0.25-m² square and soil samples were collected to a depth of 5 inches within (400 ft or less) and outside (700 ft) of previously established congregation areas along one transect within each pasture. Forage P concentration increased with increasing soil available P content and decreased late in the grazing season. On average, the P concentrations of the forages exceeded the P requirement of lactating beef cows throughout the grazing season. A model of monthly forage P concentration predicted that the probability that P supplementation of cows would be necessary wouldn’t increase until October.

Keywords: ASL R2777

How to Cite:

Pille, K. & Russell, J. R., (2013) “Effects of Season and Soil Available Phosphorus Content on the Phosphorus Concentration of the Forage in Cool-Season Grass Pastures of Southeastern Iowa”, Iowa State University Animal Industry Report 10(1). doi: https://doi.org/10.31274/ans_air-180814-685