Otnitrogen Immobilization and Remineralization in Four Cultivated Soils from Eastern France

摘要

Nitrogen immobilization and remineralization from a fertilizer supplied as 15N ammonium sulfate were determined by hydrolytic fractionation of organic nitrogen with HCl 6N into: Acid-Soluble Distillable Nitrogen (NSAD), acid-soluble Non-Distillable nitrogen (NSAnD) and non-hydrolysable nitrogen (Nnh). The study was carried out on Ap horizon of four representative agricultural soils from Eastern France: A rendzina (Typic Rendoll), a pelsol (Vertic Eutrochrept) and brown leached soil (Typic Hapludalf). After one month of incubation under controlled conditions, the immobilization of the fertilizer was higher in the rendzina (24.5%) and pelsol (24.1%) or acid brown soil (16.9%). Conversely, the comparison of immobilized 15Namounts befor and after cultivation, indicated that remineralization in the brown soils (acid brown soil 59.2%, brown leached soil 51.2%) was approximately twice higher as in the rendzina (21.1%) and pelsol (28.7%). These results show that with an Italian rye-grass used as test plant the remineralization was higher in the brown soils than in the tow clayed soils. Although the three NSAD, NSAnD and Nnh fractions participate in both, immobilization and remineralization process, the NSAnD compartment was shown to be the most active. The fact in presence of plants, part of the non-hydrolysable nitrogen fraction was biodegradable, is of particular interest.