Produtividade de milho e potencial de perdas de fósforo em Argissolo fertilizado com cama de frango

• Ano de defesa: 2008
• Autor(a) principal: Abdala, Dalton Belchior
• Orientador(a): Silva, Ivo Ribeiro da
• Banca de defesa: Freire, Maria Betânia Galvão dos Santos , Martinez, Hermínia Emília Prieto
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Mestrado em Solos e Nutrição de Plantas
• Departamento: Fertilidade do solo e nutrição de plantas; Gênese, Morfologia e Classificação, Mineralogia, Química,
• País: BR
• Palavras-chave em Português: Agricultura orgânica; Fósforo orgânico; Enthrophication
• Palavras-chave em Inglês: Organic agriculture; Organic phosphorus; Enthrophication
• Área do conhecimento CNPq: CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::CIENCIA DO SOLO
• Link de acesso: http://locus.ufv.br/handle/123456789/5413

The use of organic residues in agriculture as fertilizers or soil amendments has gained importance in Brazil as organic agriculture has expanded and fertilizer prices have increased substantially. However, studies that relate manure rates, especially poultry litter (PL), to maximize crop yield with minimum risk to the environment, are scarce. The present study was carried out under field conditions in an Ultisol to evaluate corn grain yield, the changes in soil chemical characteristics, and the P loss potential as a result of surface application of increasing rates of PL for three consecutive years. The PL rates used were 0, 5, 10, 25, 50 and 100 t ha- 1 (DW basis) and they were annually broadcast for three consecutive years and corn was cultivated. The reported soil chemical characteristics were determined after the third year of corn cultivation, thus reflecting the cumulative effect of PL application. It was found that the application of PL had positive effects on corn grain yield (CGY), which ranged from 4423 in control plots to about 12 000 kg ha-1 in high PL rate treatments. In the third year it was estimated that a maximum physical grain yield (ŷ max) of 12 500 kg ha-1 could be achieved with a PL rate of 74.7 t ha-1. However, a more economical grain yield of 11 207 kg ha-1, assigned as 0.9 ŷ max, could be achieved with a PL rate of 21.7 t ha-1. The application of such a high PL rate (74.7 t ha-1) led to a degree of soil P saturation of 21 % estimated with Mehlich-3 (DPSM-3), and a Mehlich-3 P (PM-3) concentration (131 mg kg-1), below the threshold (critical) value, that most environmental indices warn for a potential risk of P loss. Nevertheless, soil water soluble P (WSP) concentration ranged quite above the environmental threshold level, indicating that DPSM-3 values above which P losses are accentuated are lower than those found for other less weathered soils. This fact demonstrates that soil test results or the DPS taken solely provides limited indication into P loss potential and suggests the need of taking the WSP into account to relate to P loss potential. As such, an environmental threshold that also considers WSP critical level led to a more realistic indication of P loss potential. If such WSP threshold is taken into account, an estimated PL rate of 5.1 t ha-1 would be recommended. The observed changes in soil chemical attributes included increases in soil nutrients concentration (N, P, K, Ca2+, Mg2+ and Zn), Na+, pH and total C, and a decrease in exchangeable Al. Finally, the results indicate the PL rate required to maximize CGY would lead to soil P saturation and a WSP concentrations that are well above the environmental threshold. Hence, when recommending PL rate to corn it is suggested that analysis of WSP should be taken into account other than simply grain yield, PM-3 concentrations and the DPS thresholds.