Extração de fósforo em solos cultivados com cana-de-açúcar e suas relações com a capacidade tampão

Abstract

RESUMOApesar da preocupação com a produtividade esperada, a recomendação de adubação fosfatada para o Estado de Pernambuco é omissa quanto à influência da capacidade tampão dos solos na disponibilidade de P. Objetivou-se, então, neste trabalho, avaliar métodos de extração para estimativa do P disponível considerando-se o teor e a qualidade da fração argila, além das características mineralógicas, químicas e físicas dos solos. Os experimentos foram conduzidos em condições de campo, na Zona da Mata de Pernambuco, em cinco solos: Argissolo Amarelo distrocoeso (PAdx); Latossolo Amarelo distrófico (LAd); Argissolo Amarelo distrófico (PAd); Gleissolo háplico eutrófico (GXve) e Espodossolo cárbico duripânico (EKo). Os tratamentos consistiram em sete doses de P, determinadas em função da capacidade máxima de adsorção de P (CMAP). O delineamento experimental foi em blocos ao acaso, com quatro repetições. Nas amostras de solo coletadas após a aplicação dos tratamentos, determinou-se o teor de P pelos extratores Mehlich-1, Mehlich-3, Bray-1 e Resina de Troca Iônica (RTI). A RTI não apresentou correlação com características químicas ou físicas dos solos, tendo extraído P indistintamente, independente do solo; no entanto, Mehlich-1 mostrou-se altamente sensível à capacidade tampão de P do solo.Palavras-chave: extratores de P, capacidade tampão de P, adsorção de P Extraction of phosphorus in soils cultivated with sugarcane and relationship with buffer capacity of the soil ABSTRACT Despite concerns with expected production, the phosphate fertilizer recommendations for Pernambuco do not take into account influence of the buffer capacity of soil on P availability. Therefore, this work had as objective to evaluate extraction methods to estimate P availability considering content and quality of clay fraction as well mineralogical, chemical and physical soil characteristics. The experiments were carried under field conditions at 'Zona da Mata' of sugarcane cropping area of the State. Five soils were used: Argisol Yellow distrocoeso (PAdx); Latosol Yellow distrophic (LAD); Argisol Yellow distrofic (PAd); Gleisol haplic eutrophic (GXVe); and Espodosol carbic duric (ESKo). The treatments consisted of seven doses of P, determined in function of the P maximum capacity of adsorption (PMCA). The experimental design was a completely randomized treatment block, with four replications. In soil samples collected after treatment application, P was determined by Mehlich-1, Mehlich-3, Bray-1 and ion-exchange resin extractors. Ion-exchange resin did not present correlation with any physical or chemical characteristics of the soils, having extracted P indistinctly, and independent of the soil. However, Mehlich-1 was highly sensible to buffer capacity of P in soil.

Mineralogy and Maximum Phosphorus Adsorption Capacity in Soybean Development

“…However, the TH higher adsorption energy, whose saturation happened at 220 mg dm -3 of adsorbed P, reveals difference in the mineralogical constitution of the clay fraction, consistent with similar studies (Simões Neto et al, 2009;Corrêa et al, 2011;Oliveira, Gatiboni, Miquelluti, Smyth, & Almeida, 2014;Camargo et al, 2015).…”

“…Among the models, there is a preference for the Langmuir isotherm, because it allows to obtain the maximum soil phosphorus adsorption capacity (PAC) and the constant "k", related to the energy of this element binding to the soil (Novais & Smyth, 1999). As it turns, the PAC is strongly associated with the clay content and the type of mineral present in the soil (Rolim Neto et al, 2004;Simões Neto et al, 2009;Corrêa, Nascimento, & Tavares, 2011).…”

Phosphorus extracted by ion exchange resins and mehlich-1 from oxisols (latosols) treated with different phosphorus rates and sources for varied soil-source contact periods

“…However, in the clayey soil (LV), with lower remaining P (Table 1), the difference between the results in the comparison of the extractors was greater (much less for M1). In the sandy soils (LVA and LA) (Table 1), which is a condition for lower M1consumption, the extracted P contents approached, although statistically still lower, the levels of the resins ( the soil, e.g., of the clay content (Bortolon & Gianello, 2008), or more appropriate, remaining P (Simões Neto et al, 2009), to compare the results of available P extracted by consumption-sensitive extractors such as M1 and non-sensitive (or very little sensitive) extractants such as Ionic Resins. This tendency was explained by Gianello (2008b) andSimões Neto et al (2009), who mentioned the key influence of the soil clay content on the extraction capacity of M1 and AR.…”

“…Thus, for a correct interpretation of P availability, the phosphorus buffering capacity (PBC) or P capacity factor must be known. This factor is estimated from soil properties correlated with the clay content or with remaining P, when PBC-sensitive extractants such as Mehlich-1 are used Simões Neto et al, 2009). …”

Acúmulo de nutrientes e decomposição do palhiço de cana em função de doses de vinhaça

“…Além dos benefícios no campo, o correto manejo da adubação torna-se de suma importância na qualidade da canade-açúcar, influenciando a porcentagem aparente de sacarose contida no caldo da cana (POL%), açúcares redutores (AR), sólidos solúveis (BRIX) e pureza de caldo (SIMÕES NETO et al, 2009;SANTOS et al 2011;BENETT et al, 2012;TEIXEIRA FILHO et al, 2013). Assim, a qualidade da matéria-prima da cultura é definida como o conjunto de características que a cana-de-açúcar deve apresentar, atendendo às exigências da indústria, por ocasião do processamento, em especial o teor de sacarose e a fibra industrial (MOURA et al, 2005).…”