Biochemical Quality of Crop Residues and Carbon and Nitrogen Mineralization Kinetics under Nonlimiting Nitrogen Conditions
- I. Trinsoutrota,
- S. Recousb,
- B. Bentza,
- M. Line`resc,
- D. Che`nebyd and
- B. Nicolardota
INRA - Unit e ´ d'agronomie de Ch a ˆ lons-Reims, Centre de Recherche Agronomique, 2 esplanade Roland Garros, BP 224, 51686 Reims cedex 2, FrancebINRA - Unite´ d'agronomie de Laon-Pe´ronne, rue Fernand Christ, 02007 Laon cedex, FranceINRA - Station d'agronomie, 71 avenue Edouard Bourlaux, BP 81, 33883 Villenave d'Ornon cedex, FrancedINRA - CMSE Laboratoire de Microbiologie des Sols, 17 rue Sully, BP 1540, 21034 Dijon cedex, France
Statistical relationships were established between the fate of C and N from 47 types of crop residues and their biochemical characteristics during a soil incubation at 15°C. The incubations were carried out under nonlimiting N in order to differentiate the effects of biochemical characteristics of residues from those of soil N availability. Depending on the residue, the apparent mineralization of residue C after 168 d varied from 330 to 670 g kg−1 of added C. Mineralization kinetics were described using a two-compartment decomposition model that decomposes according to first-order kinetics. Amounts of C mineralized after 7 d and the decomposition rate coefficient of the labile fraction were related mainly to the soluble C forms of the residue. No statistical relationship was established between the N concentration of residues and their decomposition in the soil. The incorporation of crop residues into soil led to various soil mineral N dynamics. Two residues caused net N mineralization from the time of their incorporation, whereas all the others induced net N immobilization (1–33 g N kg−1 of added C). After 168 d, only residues with a C/N ratio <24 induced a surplus of mineral N compared with the control soil. The mineral N dynamics were related mainly to the organic N concentration of the residues and to their C/N ratio. At the start of incubation, these dynamics were also influenced by the presence of polyphenols in the plant tissues. Finally, this study showed the need to include the biochemical quality of crop residues in any C and N transformation models that describe decomposition. In contrast, the N concentration or C/N ratio of the residues are sufficient to predict the net effects of crop residues on soil mineral N dynamics.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
Copyright © 2000. . Published in Soil Sci. Soc. Am. J.64:918–926 .