Substance turnover in drained field
1994
Timmusk, T. (Estonian Agricultural Univ., Tartu (Estonia). Inst. of Water Management)
The pollution of groundwater can become a problem in Estonia. We supposed that an increase of nitrates in the water is connected with increasing usage of mineral fertilizers. Nitrification in some cases is a reversible process. When free oxygen is lacking and there is enough carbon, then the denitrifying bacteria can deoxidate nitrates and thus release gaseous nitrogen. It is possible to regulate water and air regime of soil by subirrigation. In order to test this method in Estonia in the spring of 1994 the experimental field was founded in Vanda main ditch catchment. In this area the research that concerns runoff and chemical composition of water has been carried out once a month throughout the year since 1988. The leaching of mineral nitrogen has been 12.1 - 17.5 kg/ha per year.
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