ABSTRACT
Techniques......................................................................... 492 13.5 Recommendations and Future Research.......................................... 492 Notation ...................................................................................................... 494 References ................................................................................................... 496
A variety of gases, some in very large quantities, are exchanged at the soil surface in terrestrial ecosystems. Measurement of the rates at which these exchanges take place can serve several goals. Gaseous emissions are often used to assess the impacts of agricultural and forest management on the atmospheric environment (e.g., ammonia, greenhouse gases, and pesticides). Also, several soil biological or chemical reactions can be more easily quantified by measuring the emission rate of their gaseous products than by monitoring the rate of change in the amounts of soil substrates (e.g., soil carbon and nitrogen) (see Chapter 15). Finally, real-time measurements of evaporation rates from agricultural fields can be used in support to irrigation scheduling (see Chapter 4).
