Nutrient Retention Performance of a Crushed Limestone Floor Surface in a Bedded Hoop Barn with Confined Beef Cattle

Bedded confinement systems with partial concrete floors are increasingly being adopted by beef cattle feeders. The objective of this study was to determine the extent that manure nutrients moved into the soil below the geotextile fabric and packed limestone screenings floor of a bedded hoop barn used for beef cattle feeding at the ISU Armstrong Research and Demonstration Farm. Soil samples were taken (shallow and deep) before construction in 2004 and in 2008 after 7 groups of cattle were fed. Although single samples before and after animal feeding cannot provide conclusive evidence of moisture or nutrient migration, comparison of the sample results confirm a trend consistent with slow migration of manure nutrients into the soil profile. Phosphorus, calcium and magnesium did not show consistent or major trends with time. Organic matter showed a consistent increasing trend in both shallow and deep samples. Shallow sampling showed a marked increase only in nitrate-nitrogen, from 1.51 ppm to 11.47 ppm. These results are consistent with measurable, but very slow migration of moisture and nutrients into the soil profile. Additional soil tests over time and performance of an infiltration ring study may give more conclusive answers in the future