Predicting N transformations from organic inputs in soil in relation to incubation time and biochemical composition
Seventeen different added organic materials (AOM) in a sandy soil were incubated under controlled laboratory conditions (28°C, 75% WHC), and examined for C and N mineralisation. The transformation of added organics (TAO) model has been presented in previous work for predicting C mineralisation. The two variables (very labile and stable fractions of AOM) used in TAO have been related to the biochemical characteristics of the AOM. The transformed added organic N fraction (TAONF) was estimated from the remaining CAOM and NAOM linked by the C-to-N ratios. TAONF was split (Pim parameter) into immobilised N (imN) and inorganic N (inorgN). When necessary, an additional N mineralisation of imN was predicted by first order kinetics (constant kremin). The TAO version with the two parameters Pim and kremin allowed us to predict very different dynamics of N mineralisation and N immobilisation from the AOM. In a few cases, another first order kinetic law (constant kv) was used to predict N volatilisation from inorgN. Biochemical characteristics of AOM were used for predicting N transformations. First, at each incubation date, inorgN was approximated to inorgNa = [alpha](N-to-CAOM) + [bêta] by linear regression. The [alpha], [bêta] and - [bêta]/[alpha] (C-to-NAOM threshold for mineralisation/immobilisation) were related to time. The TAO expression (1-Pim)TAONF was then replaced by the proposed approximation inorgNa as a function of incubation time and C-to-NAOM. Secondly, significant relationships were computed between kremin and organic fibre content of AOM. Finally, a TAO approximation was proposed for predicting the simultaneous transformations of C and N, only using biochemical data (plus the kv parameter in a few cases of N volatilisation). For all AOMs, the validity of the approximation and its borderline cases were examined by comparing the two TAO versions.
| Main Authors: | , , , |
|---|---|
| Format: | article biblioteca |
| Language: | eng |
| Subjects: | P33 - Chimie et physique du sol, U10 - Informatique, mathématiques et statistiques, F04 - Fertilisation, sol sableux, modèle de simulation, azote, minéralisation, carbone, immobilisation, amendement organique, biochimie, propriété physicochimique du sol, résidu de récolte, http://aims.fao.org/aos/agrovoc/c_6781, http://aims.fao.org/aos/agrovoc/c_24242, http://aims.fao.org/aos/agrovoc/c_5192, http://aims.fao.org/aos/agrovoc/c_15999, http://aims.fao.org/aos/agrovoc/c_1301, http://aims.fao.org/aos/agrovoc/c_27550, http://aims.fao.org/aos/agrovoc/c_12965, http://aims.fao.org/aos/agrovoc/c_910, http://aims.fao.org/aos/agrovoc/c_7182, http://aims.fao.org/aos/agrovoc/c_16118, |
| Online Access: | http://agritrop.cirad.fr/515317/ http://agritrop.cirad.fr/515317/1/515317.pdf |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|