A combination of biological activity and the nitrate form of nitrogen can be used to ameliorate subsurface soil acidity under dryland wheat farming

Abstract

The management of subsurface soil acidity remains a challenge. We tested the ability of calcium nitrate fertilization to force net anion uptake by wheat within acidic subsurface layers and hence its ability to increase, or at least maintain, soil pH within the acidic layer. The trials were conducted at two field sites: the moderately acidic site ran for 3 years (2006-08) while the trial at the most acidic site was conducted for 2 years (2006-07). Five treatments (nitrogen form and application method) were compared. Uptake efficiency of nitrogen (N) as measured by 15N was similar (at ~40 to 70%) for both urea and nitrate sources at both sites. The urea source acidified the soils (up to 0. 2 p..