Assessment of N mineralization and leaching in soil using a new in-situ incubation method

RAMIRAN International ConferenceTowards sustainable soil management, the application of organic residues to the soil has to be based on criteria sustained by experimental studies. Several methods for estimating the amount of N that mineralizes from landapplied organic residues can be used but laboratory incubations has been the main methodology used due to several advantages related to practical and economical aspects (Qafoku et al., 2001). However, this type of methodology is performed under controlled temperature and moisture content, at optimal conditions for the mineralization process, limiting the extrapolation of laboratory derived values to the field conditions (Hanselman et al., 2004). Since N mineralization process can be affected by the dynamic of these factors, several authors consider field incubations as a more realistic method to assess N mineralization (Subler et al., 1995; Halselman et al., 2004). Nevertheless, the quality of the results obtained depends on the type of reactor devices used for measuring N mineralization under these conditions. In fact, various reactors devices described in the specific literature, like buried bags (Eno, 1960) or covered cylinders (Raison et al., 1987), reveal some disadvantages or limitations in monitoring N mineralization in field conditions. More recently, refining reactor devices, by introducing exchange resins, promoted a more sensible indicator comparatively to other methods since temperature, moisture content and aeration inside the containerized soil are close to undisturbed soil (Halselman et al., 2004). Considering that resin-trap incubation is the most promising in-situ technology in measuring nitrogen net mineralization rates from organic soil amendments, the aim of the present study is to evaluate the quality of the results obtained by using a new in-situ incubation device for the determination of N mineralization kinetics in the soil as well as the potential of nitrogen leaching as a potential alternative use in field studies of N mineralization kinetics from organic residues applied to soils