EFFECTS OF SHALLOW SOIL-INJECTED ANIMAL BLOOD ON PASTURE GROWTH AND SOIL-NITROGEN

Animal blood was injected into the soil in inverted-T-shaped slots at two application rates (25 and 50 m(3) ha(-1)) and depths (75 and 115 mm) to determine the effects on pasture growth and the fate of the nitrogenous component of blood in the soil. Pasture growth was significantly improved when animal blood was injected compared with no application. There were no clear differences attributable to rates of application, although there may have been a tendency towards higher pasture yield when blood was applied at 115 mm depth than at 75 mm. From these data and calculations of apparent nitrogen recovery ratios it appears that the threshold level of application (for pasture response) was 25 m(3) ha(-1) (equivalent of 340 kg N ha(-1)). Laboratory analyses of soil samples, collected to determine the spread of solute movement from the point of injection, suggested that over a 6-week period following injection, the solute (Kjeldhal nitrogen) had infiltrated to depths of 150-200 mm and spread laterally to 100 mm although the volume and rate of nitrogen solute lost by leaching from blood-treated soil was markedly low compared with when the soil was injected with water.