Relationship of soil phosphorus with uranium in grassland mineral soils in Ireland using soils from a long‐term phosphorus experiment and a National Soil Database

Abstract

AbstractPhosphorus fertilizer contains contaminants that may increase the content in the soil and in plants. The relationship between soil P and soil uranium (U) was investigated to determine potential effects of P‐fertilizer use. This study is based on a long‐term experiment (38 years with 0, 15, and 30 kg fertilizer P ha–1 y–1) for beef production on grassland at Teagasc, Johnstown Castle, Wexford, Ireland and also on soils from a National Soil Database (NSD). The NSD soils were taken at fixed locations on a predetermined grid system at the density of one sample every 50 km2. Of the 1310 samples in the NSD, the 760 grassland mineral soils were selected for this study. The aim was to determine to what extent P fertilizer increases the content of U in the soil. The results showed that there was a small but significant increase in soil U in the high‐P treatments, which contained high levels of soil P, in the long‐term field experiment. The results from the NSD showed that there was not a significant relationship between extractable (Morgan's) soil test P (STP) and U. It is concluded that the use of chemical P fertilizer at normal rates used in agriculture in Ireland is not a major threat to U content of soil based on the results of this study. There was a significant relationship between total P and STP, in the NSD, with the latter making up approx. 1% of the former. Soil available P increased with soil pH, probably reflecting the use of chemical P fertilizer and lime on agricultural soils.