Soil organic matter and nitrogen interaction in a tropical agrosystem
Creators
- 1. Office de la Recherche Scientifique et Technique d'Outre - Mer (ORSTOM), 75 - Paris (France)
- 2. CEA Centre d'Etudes Nucleaires de Cadarache, 13 - Saint-Paul-les-Durance (France)
- 3. ISR, Bambey (Senegal)
Description
The effects of chemical and organic fertilization were studied in a pot experiment with 15N-urea and 14C 15N maize crop residues (straw and composted straw). Distribution of isotopes and organic matter within soil fractions were recorded by a particle size fractionation with sieves. 5 size fractions were obtained:3 fractions superior to 50 μm where organic matter corresponded to plant residues at different humification stages, an organo-mineral fraction 0-50 μm (humus s.s.) and a watersoluble fraction. High plant productivity, high N-urea utilization, low N-urea losses and increase in soil C and N contents were only recorded with the composting treatment (PC) as compared to the control without amendment (T) and to the straw amendment (P). In PC treatment nitrogen derived from urea (N-urea) was mainly present as fractions superior to 50μm (indicating a nitrogen reorganization by root system); for P and T, N-urea was more important in the watersoluble fraction, which is susceptible to losses by leaching. Humification processes were mainly due to 'residual' pathway as the remaining C and N organic amendment were located in fraction superior to 50 μm. C and N straw distribution in soil were significantly different and might be correlated with the initial straw composition. In conclusion the size fractionation of soil organic matter associated with tracer technics was a powerfull method for studying plant residues decomposion and interactions between organic mater and chemical mitrogen in the soil-plant system. (Author)
Abstract (Portuguese)
Estudaram-se os efeitos da fertilizacao quimica e organica em frasco de experimentacao com 15N-ureia e restos de plantacao de milho marcados com 14C e 15N(palha e palha adubada). Fracionou-se a materia organica do solo por metodo granulometrico (tamisacao). Determinaram-se seus teores isotopicos nas diferentes fracoes. Obtiveram-se 3 fracoes de tamanhos de grao superiores a 50 μm, uma organo-mineral de 0-50 μm e uma hidrossoluvel. Observaram-se elevada produtividade, utilizacao elevada de 15N-ureia, baixas perdas de 15N-ureia e aumento nos teores de C e N no solo, apenas no tratamento adubado (PA), quando comparado ao controle sem enriquecimento (T) e ao enriquecimento com a palha (P). No tratamento PA, o N derivado da ureia (N-ureia) encontrou-se principalmente nas fracoes superiores a 50 μm (indicando uma reorganizacao do N pelo sistema radicular); para P e T, o N-ureia foi mais importante na fracao hidrossoluvel, susceptivel a perdas por lixiviacao. Processos de humificacao deveram-se principalmente a uma via 'residual', como o indica a localizacao de C e N nas fracoes maiores do que 50μm. Interpretam-se as diferencas de distribuicao para C e N da palha, em funcao de sua composicao inicial. Conclui-se que o fracionamento granulometrico da materia organica associado as tecnicas isotopicas e um metodo privilegiado de estudo da decomposicao de residuos vegetais no solo e interacoes nitrogenio-materia organica entre solo-planta. (M.A.)Additional details
Additional titles
- Subtitle (English)
- Study by size organic matter fractionation and isotope techniques
- Original title (French)
- Interaction entre la matiere organique du sol et l'azote dans un agrosysteme
- Original subtitle (French)
- Etude a l'aide du fractionnement de la matiere organique et de techniques de marquage isotopique.
Publishing Information
- Imprint Title
- Proceedings of the Regional Colloquium on Soil Organic Matter Studies
- Imprint Pagination
- 263 p.
- Journal Page Range
- p. 185-192.
- Report number
- INIS-BR--200
Conference
- Title
- Regional Colloquium on Soil Organic Matter Studies.
- Dates
- 18-22 Oct 1982.
- Place
- Piracicaba, SP (Brazil).
INIS
- Country of Publication
- Brazil
- Country of Input or Organization
- Brazil
- INIS RN
- 15072363
- Subject category
- S60: APPLIED LIFE SCIENCES;
- Resource subtype / Literary indicator
- Conference
- Descriptors DEI
- CARBON 14; FERTILIZERS; HUMUS; NITROGEN 15; PARTICLE SIZE; PRODUCTIVITY; SOILS; UREA
- Descriptors DEC
- BETA DECAY RADIOISOTOPES; BETA-MINUS DECAY RADIOISOTOPES; CARBON ISOTOPES; CARBONIC ACID DERIVATIVES; EVEN-EVEN NUCLEI; ISOTOPES; LIGHT NUCLEI; NITROGEN ISOTOPES; NUCLEI; ODD-EVEN NUCLEI; ORGANIC COMPOUNDS; ORGANIC NITROGEN COMPOUNDS; RADIOISOTOPES; SIZE; STABLE ISOTOPES; YEARS LIVING RADIOISOTOPES
Optional Information
- Notes
- Imprint:Anais do Coloquio Regional sobre Materia Organica do Solo.