Bromide is commonly used to simulate the movement of nitrate fertilisers through the soil profile. However, there exists nocomparative evaluation of the leaching properties of Br- and NO3--N under local soil and rainfall conditions at Bloemfontein. The purpose of this work was to conduct a field experiment to evaluate the leaching behaviour of Br- in comparison with NO3--N onthe Bainsvlei soil of South Africa under natural rainfall conditions. For this purpose, KBr- and KNO3 solutions were applied to a2.45 x 2.45 m2 plot at rates of 13.5 g BrÂ·m-2 and 20 g NÂ·m-2 respectively. The subsequent movement of the solutes through the soil was investigated through studies of the water and mass balances, determined from soil samples taken from a 1600 mm deep soil profile during the period October 2000 to May 2001, the rainy season in Bloemfontein. The results were also analysed with the one-dimensional convective dispersive equation and stream tube models. Two important results were derived from the study: Br can be used with confidence as a substitute for NO3--N in studies of the movement of the latter through soils, and it is more economical and environmentally friendly to distribute the application of nitrate over the growing season of a crop, instead of applying it as a batch at the time of planting.
|Number of pages||8|
|Publication status||Published - 2004|