Injecting urea for preserving high-moisture hay in large round bales

Large round bales of high-moisture hay were injected with a urea solution in the amount of 5 percent by weight of the bale dry matter. Breakdown of the urea solution into ammonia and subsequent movement of the ammonia throughtout the bale volume was to provide the hay preserving action. An injection system consisting of a probe and a pressurized liquid supply tank was designed and used for the injections. Two patterns of injection--at the bale center or at three equispaced points half way from the center to the outer surface--were compared for hay preserving effectiveness. Comparisons were made to control bales which received no urea. Bale temperatures at the center and at a point 1 foot from the outer surface were sensed by thermo couples and monitored over a 35-day period. Movement of nitrogen (theoretically by formation and diffusion of ammonia from the urea) throughout the bale volume was measured by sampling cross sections of the bales in a wheelspoke pattern at 2, 7, 15 and 35 days after injection and determining the concentration of nitrogen in the samples by laboratory tests.