Caracterização, decomposição e biodisponibilidade de nitrogênio e fósforo de materiais orgânicos de origem animal e vegetal / Characterization, decomposition and mineralization of nitrogen and phosphorus of organic materials from animals and plants

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

This work presents results of a set of experiments carried out under laboratory, green house and field conditions regarding to the chemical and biochemical characterization of organic materials: raw animal manures, industrial residues, green manures and composts elaborated with coffee husk. With the objective to evaluated their decomposition, mineralization of organic forms of N and P, and nutrient recovery by Brachiaria decumbens. This information will be the base to build up organic fertility programs. The chemical characterization of the organic materials included the determination of organic matter, total organic carbon, macro and micronutrients and trace elements; the biochemical characterization, included water soluble carbon, total soluble carbohydrates, total soluble polyphenols and polyphenol s capability to complex protein. Furthermore, for the green manures was determined the insoluble fiber in neutral and acid detergent, hemicellulose, cellulose, and lignin content; for the composts the humic fractionation was performed, and the carbon and nitrogen content were determined in those fractions. The decomposition was evaluated through respiration experiments and the organic nitrogen and phosphorus mineralization by incubation experiments under controlled environmental conditions: humidity at 80% of the field capacity and temperature of 25 1oC. For the green manures the percentages of biomass, as a dry matter loss, and release of total nitrogen and phosphorous were evaluated using the litterbag method. The nutrient bioavailability was quantified through experiments that evaluated the growth and nutrient uptake of nitrogen and phosphorus by Brachiaria decumbens in an Oxisol fertilized with different organic materials. The results indicated that animal manures and green manures were good sources of nitrogen, and the meat and bone meal of phosphorus. For an incubation period of 30 days, the materials with greater decomposition were Crotalaria juncea (439,80 mg CO2/100 g of soil) and Brachiaria decumbens (425,76 mg CO2/100 g of soil); followed by chicken manure (380,25 mg CO2/100 g of soil) and meat and bone meal (363,48 mg CO2/100 g of soil). For an incubation period of 60 days, the materials with greater potential of nitrogen mineralization were earthworm compost (1625 mg N kg 1), compost of mucilagen with swine slurry and coffee husk (1163 mg kg 1), Crotalaria juncea (792mg N kg-1), composts of sewage sludge (4500 mg N kg-1) and town wastes (2000 mg N kg-1). The materials that release greater quantities of inorganic phosphorus to the soil for an incubation period of 45 days were the meat and bone meal (1144 mg P kg-1), followed by pig manure (579 mg P kg-1), chicken manure (484 mg P kg-1) and compost of sewage sludge (206 mg P kg-1). Under field conditions for a period of 150 days, the loss of dry matter allowed to identify in Praia D Anta, Araponga, MG., green manures of rapid decomposition Amaranthus spinosus and Stizolobium aterrimum, Calopogonium muconoides; intermediary Crotalaria juncea, Cajanus cajan and Leucaena leucocephala; and low Brachiaria decumbens and Inga edulis. The process of decomposition and mineralization of green manures was controlled by their biochemical characteristics, especially the lignin+polyphenols/nitrogen ratio (r = -0,88**), and the polyphenol s capability to complex protein (r = -0,86**). The materials with greater release of nitrogen were Amaranthus spinosus and Crotalaria juncea, and regarding to the release of phosphorus were Cajanus cajan and Stizolobium aterrimum. In Pedra Redonda, Araponga, MG., the percentages of decomposition of the different materials as an average were 18% lower due to the negative effect of soil and environmental conditions (higher altitude, lower temperature, evaporation and soil humidity). Such condition also reduced mean nitrogen (8%) and phosphorus (6%) mineralization. The organic fertilization of Brachiaria decumbens indicated that when the soil was amended with phosphorus, the biomass increased for all the treatments, except to the meat and bone meal that was reduced by 50%. The phosphorus was a limiting factor for the uptake of nitrogen from the chicken manure, Crotalaria juncea, Leucaena leucocephala, and coffee husk; and the nitrogen was limiting to the uptake of phosphorus from the earthworm compost. The organic material with greater agronomy potential as indicated by the biomass production and nitrogen and phosphorus uptake by Brachiaria decumbens were the chicken and pig manures, earthworm compost and meat and bone meal.

ASSUNTO(S)

ciclagem de nutrientes matéria orgânica leguminosas nutrient cycling organic materials ciencia do solo brachiaria decumbens

ACESSO AO ARTIGO

Documentos Relacionados