Volume 27, 114

Tropical Grasslands (1993) Volume 27, 114–120

Simulation of salt leaching in grazed grassland soils using bromide as a tracer

RAÚL S. LAVADO, ALICIA F. DE IORIO, ALICIA RENDINA and ALEJANDRA IRIARTE

Departamento de Suelos, Facultad de Agronomia, Universidad de Buenos Aires, Buenos Aires, Argentina

Abstract

Lowering of soil salinity is important in improving the productivity of grasslands in parts of Argentina. Under rainfed conditions, it is very difficult to reduce soil salt content. Soil cover can be modified by means of grazing management to test the effects on the salinisation process in soils. Grasslands on 3 soils in the Flooding Pampa were grazed or ungrazed and subjected to natural variable rainfall conditions.
Salt leaching was simulated by using bromide (Br) as a tracer. Its concentration was measured using a specific bromide ion electrode.
The tracer was leached from the soils in the ungrazed treatment at different rates, reaching the background level within 2 years. Conversely, in soils under grazing the tracer moved more slowly.
These results support the hypothesis that the rate of salt leaching can be accelerated through grazing management. The effect of soil type on the benefits obtained is discussed. It is concluded that, whenever grazing is managed to control the soil salt content, soil properties must be considered.