Effect of sulfur fertilization on yield and chemical composition of corn forage and utilization of corn silage by sheep

Sulfur (S) deficiencies have become an increasing problem in the United States. A field experiment, in a latin square design, was conducted to investigate effects of S fertilization as 0 and 67 kg/ha as a single or split application on corn (Zea mays L.) forage yield and chemical composition. Sulfur fertilization by either method increased yield of whole plant and grain 7% and increased number of plants with two ears. Total S and sulfate-S concentration in whole corn plants, leaf, stem, and grain were increased with S fertilization. Corn forages were ensiled at harddent stage (35% dry matter). Sulfur fertilized corn silages (N/ S=42 and 43) and non-S fertilized silage (N/ S=62) supplemented at two rates with sodium sulfate (N/ S=l2 and 45) were fed to sheep in metabolism and palatability trials. Both experiments were conducted as a randomized block design with six replications per treatment. All silages were supplemented with urea (6.7 g/ d). Digestibility of dry matter and cell wall components and apparent absorption of Sand N were increased with S fertilization and S supplementation. Nitrogen retention was increased 14% by S supplementation (N/S=l2) and 31% by S fertilization. Sheep fed N/ S=12 silage had lower blood hematocrit and hemoglobin levels then those fed S fertilized or N/ S=45 silages. Blood urea-N levels were higher in sheep fed S fertilized silages. Increasing dietary S by fertilization or supplementation had no measurable effect on dry matter intake.