Mobility of inorganic and organic phosphorus forms under different levels of phosphate and poultry litter fertilization in soils

Abstract

The eutrophication of aquifers is strongly linked to the mobility of P in soils. Although P mobility was considered irrelevant in a more distant past, more recent studies have shown that P, both in organic (Po) and inorganic forms (Pi), can be lost by leaching and eluviation through the soil profile, particularly in less weathered and/or sandier soils with low P adsorption capacity. The purpose of this study was to determine losses of P forms by leaching and eluviation from soil columns. Each column consisted of five PVC rings (diameter 5 cm, height 10 cm), filled with two soil types: a clayey Red-Yellow Latosol and a sandy loam Red-Yellow Latosol, which were exposed to water percolation. The soils were previously treated with four P rates (as KH2PO4 ) to reach 0, 12.5, 25.0 and 50 % of the maximum P adsorption capacity (MPAC). The P source was homogenized with the whole soil volume and incubated for 60 days. After this period the soils were placed in the columns; the soil of the top ring was mixed with five poultry litter rates of 0, 20, 40, 80, and 160 t ha-1 (dry weight basis). Treatments consisted of a 4 x 5 x 2 factorial scheme corresponding to four MPAC levels, five poultry litter rates, two soils, with three replications, arranged in a completely randomized block design. Deionized water was percolated through the columns 10 times in 35 days to simulate about 1,200 mm rainfall. In the leachate of each column the inorganic P (reactive P, Pi) and organic P forms (unreactive P, Po) were determined. At the end of the experiment, the columns were disassembled and P was extracted with the extractants Mehlich-1 (HCl 0.05 mol L-1 and H2SO4 0.0125 mol L-1) and Olsen (NaHCO3 0.5 mol L-1; pH 8.5) from the soil of each ring. The Pi and Po fractions were measured by the Olsen extractant. It was found that under higher poultry litter rates the losses of unreactive P (Po) were 6.4 times higher than of reactive P (Pi). Both the previous P fertilization and increasing poultry litter rates caused a vertical movement of P down the soil columns, as verified by P concentrations extracted by Mehlich-1 and NaHCO3 (Olsen). The environmental critical level (ECL), i.e., the P soil concentration above which P leaching increases exponentially, was 100 and 150 mg dm-3 by Mehlich-1 and 40 and 60 mg dm-3 by Olsen, for the sandy loam and clay soils, respectively. In highly weathered soils, where residual P is accumulated by successive crops, P leaching through the profile can be significant, particularly when poultry litter is applied as fertilizer.

Short-Term Changes in Fertility Attributes and Soil Organic Matter Caused by the Addition of EM Bokashis in Two Tropical Soils

“…When organic inputs with high fertility potential are added to the tropical soils the risk of lixiviation and its negative environmental impacts increases [18]. Additionally, use of high rates of poultry litter can increase the risk of P lixiviation in the form of organic P. Successively fertilization with poultry litter or fertilization with this organic fertilizer after the mineral fertilization can increase the risk of P lixiviation [19]. Then, rational uses of EM Bokashi are necessary.…”

Phosphorus Sorption and Redistribution on Soil Solid Phase in a Brazilian Haplorthox Amended with Biosolids

“…Furthermore, topsoil P concentrations have been related to P movement below the plough layer and tile flow [1]. Recently, Gebrim et al [2] observed that P leaching through the profile can be significant in highly weathered soils, where residual P is accumulated by successive crops, particularly when poultry litter is applied as fertilizer.…”

Diagnose nutricional de variedades de cana-de-açúcar em argissolos

“…Por vez, as variedades desenvolvidas no PAdx 2 apresentaram maiores teores foliares de P, o que se atribui, possivelmente, a uma quantidade maior de P proveniente da torta de filtro (Tabela 3). O fósforo é significativo em diversas funções da cana-de-açúcar, exercendo função de destaque na formação de proteínas e em vários processos, como a fotossíntese, divisão celular e armazenamento de energia, entre outros como a maior necessidade encontrada nos três primeiros meses do estado de vegetação, aliado ao fato de ser o nutriente mais limitante na produção de cana-de-açúcar (Bastos et al, 2008;Gebrim et al, 2010;Korndorfer & Mello, 2009;Simões Neto et al, 2009 , respectivamente. Os valores dos teores foliares de P obtidos neste trabalho se situam na faixa classificada como média e adequada para a cultura, de acordo com Espironelo et al (1986) .…”