Movement of bromide as a tracer for nitrate in an Alfisol of the Indian Semi-Arid Tropics under rainfed condition uri icon

abstract

  • The variable responses of crops to added nitrogen (N) in Alfisols of the Indian semi-arid tropics are partly due to variable rainfall and partly due to variable losses of available-N. To measure the losses of N through leaching, which can be appreciable under some circumstances, a field experiment was conducted during the rainy season (June-September) of 1992, using bromide (Br) as a tracer for NO 3 - . Bromide (as NaBr) was applied to bare fallow soil at a rate of 200 kg ha?1 in microplots (2 m × 2 m) and its vertical movement was monitored periodically. Data on rainfall and Br? distribution in the soil profile on different dates of soil sampling clearly indicated that the movement of Br? was strongly dependent on rainfall. During the first month (15 June-15 July) after Br? application, with scattered and light rainfall about 90% of the added Br? remained in the soil profile (0.6 m). After continuous heavy rainfall in early August more than 90% Br? had moved beyond 0.6 m depth. This indicates a very high risk of NO 3 - leaching in this soil, and it is unavoidable without special measures to protect the applied N

publication date

  • 1995
  • 1995