Iron oxides and organic matter on soil phosphorus availability

Abstract

Continuous crop expansion has led to a growing demand for phosphate fertilizers. A sound knowledge of the dynamics of phosphorus, and its interaction with iron oxides and organic matter, can be useful to develop effective strategies for sustainable management, especially in a scenario of increasing shortage of mineral phosphate resources. In this paper, we review the relationship of phosphate to iron oxides and organic matter, and its effect on phosphorus availability. Crops typically obtain phosphate from weathered minerals and dissolved fertilizers. However, the amount of phosphorus present in the soil solution depends on the extent to which it is adsorbed or desorbed by iron oxides, which may be influenced by interactions with organic matter. Therefore, systems for fertilizer recomendation based on methodologies considering interactions between soil components such as oxides and organic matter, and the phosphorus sorption capacity resulting from such interactions (e.g. residual P analysis), may be more reliable to ensure efficient, rational use of phosphate. A contínua expansão da produção agrícola tem levado a uma crescente demanda de fertilizantes fosfatados. O conhecimento da dinâmica do fósforo no solo e suas interações com óxidos de ferro e matéria orgânica podem ser uteis no desenvolvimento de estratégias eficientes para o manejo sustentável, especialmente em um cenário de crescente escassez de fontes de minerais fosfatados. Nesta revisão bibliográfica foi abordado a relação do fósforo com óxidos de ferro e matéria orgânica, e seu efeito na disponibilidade de fósforo. As culturas, normalmente, obtém fosfato de minerais intemperizados ou fertilizantes dissolvidos. No entanto, a quantidade de fósforo presente na solução do solo depende das reações de adsorção e dessorção por óxidos de ferro, as quais podem ser influenciadas por interações com a matéria orgânica. Portanto, os sistemas de recomendação de fertilizantes com base em metodologias que consideram as interações entre componentes do solo, tais como óxidos e matéria orgânica, e a capacidade de adsorção de fósforo, resultantes de tais interações (por exemplo, análise de P remanescente), pode ser mais confiável para garantir o uso eficiente e racional de fertilizantes fosfatados.

Chemical Changes of Soil and Water in Hillside Areas Under Intensive Horticulture

“…However, successive phosphate fertilization to meet the needs of horticultural plants justify high P contents (above 100 mg dm −3 ) . The highest P contents found at a depth of 0-10 cm are from drip fertigation, which concentrates P in the upper soil layer where a higher vegetable root density can be found (up to 20 cm), as well as its low mobility in the soil profile (Paula et al, 2016;Fink et al, 2016). Because these areas are located in the hillside, high P contents are agronomically and environmentally worrisome since this nutrient may be easily carried into water sources, with a potential risk of eutrophication (Reay et al, 2012;Bai et al 2013).…”

“…Eberhardt et al (2008) also obtained a negative correlation between P and H+Al contents. According to Fink et al (2016), OM has a low potential to adsorb P as it presents essentially negative charges, unlike Fe (goethite and hematite) and Al (gibbsite) oxides, more efficient and active in P adsorption, especially in the pH range between 4.9 and 6.5, where Fe and Al oxides exhibit positive charges, strongly attracting orthophosphate anions.…”

Characterization of tirsification soil weathering processes: The case of Los Lirios wetland, Guadalquivir basin, Seville, Spain

“…Levels recorded throughout the tirsified zone are lower than those on its vertisolized base, with values of 4 and 10-12 mg 100 g -1 , respectively. Therefore, the great agricultural capacity of these tirsified soils seems to be more related to its geomorphological condition more than its chemical fertility, as the former favors a greater availability of water throughout the year the amount of phosphorus present in the soil solution depends on the extent to which it is adsorbed or desorbed by iron oxides, which may be influenced by interactions with organic matter (Almeida et al, 2003;Fink et al, 2016). Therefore, systems for fertilizer recommendation based on methodologies considering interactions between soil components such as oxides and organic matter.…”

Mineralogy and Maximum Phosphorus Adsorption Capacity in Soybean Development

“…In this scenario the Mato Grosso State Cerrado (Savanna) stands out, which holds the Brazilian largest soybean production area. However, the advanced weathering of cerrado soils limits soybean productivity, mainly due to the lack of phosphorus (P) (Souza & Lobato, 2002;Roy et al, 2017), since much of this nutrient is strongly retained in the oxidic mineralogy of these soils (Guedes, Fernandes, Souza, & Silva, 2015;Fink, Inda, Tiecher, & Barrón, 2016).…”

“…In fact, unlike iron oxides, kaolinite presents low load and specific surface area, limiting itself only to external surfaces (Melo & Wypych, 2009), conferring low fixation of anionic groups such as phosphate. Besides the type of mineral, the crystallographic attributes such as specific surface (SS), isomorphic substitution (IS), and mean diameter of the crystal (MDC) play an important role in adsorption of P (Fink et al, 2016). Thus, the high SS area, associated with low crystallinity minerals, allows higher retention of P, due to the higher density of OH-charges exposed on the surface.…”