J. B. Humphry

Effects of Nitrogen Fertilization on Phosphorus Uptake in Bermudagrass Forage Grown on High Soil-Test Phosphorus Sites

Abstract Common bermudagrass [Cynodon dactylon (L.) Pers.] was harvested from two producer sites (Latta and Stephens) with high soil-test P (286 and 153 ppm, respectively) to assess the effects of N fertilization on P uptake and potential removal in hay or silage. Ammonium nitrate was applied in split applications each year at rates totaling 0, 56, 112, 168, 224, 280, or 336 kg/ha of actual N. At the Stephens site in Yr 1, cumulative DM yield increased linearly (P 0.10) between concentration of P and N fertilization rate (overall mean = 0.40%), but concentrations of P declined in linear (P

Mineral Content of Forages Grown on Poultry Litter-Amended Soils1

Abstract Large quantities of poultry litter are applied each year to pastures in Arkansas and Oklahoma. Our objective was to monitor mineral concentrations in forages grown on poultry litter-amended soils and compare them with mineral requirements for gestating and early lactating beef cows. A total of 65 forage samples were gathered from four farms in northwest Arkansas and northeast Oklahoma from April 2000 to March 2002. Mean forage mineral concentrations were compared with beef cattle requirements using a two-tailed t test. Two-year average forage Ca, P, K, S, and Fe concentrations from each farm exceeded (P 0.05) from gestation and lactation requirements. On individual sampling dates, concentrations of Ca, P, K, and Zn rarely fell below lactation requirements. Mean forage Mg concentrations from one farm exceeded (P 0.05) lactation requirements. Mean tetany ratios from all farms were below (P 0.05) from the requirements on three farms. Forages from pastures fertilized with broiler litter may meet most but not all mineral requirements of beef cattle, and supplementation of specific minerals, particularly Mg and Cu, may be necessary.