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BIBTEX RIS

Influence of decomposition of roots of tropical forage species on the availability of soil nitrogen

1998; Elsevier BV; Volume: 30; Issue: 14 Linguagem: Inglês

10.1016/s0038-0717(98)00086-8

1879-3428

Segundo Urquiaga, Georg Cadisch, Bruno José Rodrígues Alves, Robert M. Boddey, K.E. Giller,

Bioenergy crop production and management

Immobilization of mineral N induced by decomposition of roots of four tropical forage species (Stylosanthes guianensis, Centrosema sp., Andropogon gayanus and Brachiaria decumbens) in an Oxisol was studied under laboratory conditions. Root materials had a high lignin content (12–20%) but total polyphenol content was small ( 0.99) a double exponential equation defining two compartments of root carbon of differing susceptibility to decomposition. The equation predicted that between 43% (Centrosema) and 62% (Brachiaria) of root carbon would not be decomposed even at infinite time under incubation conditions. Mineral N in the soil was immobilized rapidly at the start of the incubation, and the immobilization was greatest with the higher rate of application of root material. Although the C-to-N ratio of legume roots was narrower their higher degradability stimulated greater immobilization of soil mineral N than the grass roots. The results are discussed with reference to N immobilization and carbon sequestration in planted pastures of tropical South America.