Influence of soil pH on inorganic phosphorus sorption and desorption in a humid brazilian Ultisol

Abstract

SUMMARYLiming is a common practice to raise soil pH and increase phosphorus (P) bioavailability in tropical regions. However, reports on the effect of liming on P sorption and bioavailability are controversial. The process of phosphorus desorption is more important than P sorption for defining P bioavailability. However few studies on the relationship between soil pH and P desorption are available, and even fewer in the tropical soils. The effects of soil pH on P sorption and desorption in an Ultisol from Bahia, Brazil, were investigated in this study. Phosphorus sorption decreased by up to 21 and 34 % with pH increases from 4.7 to 5.9 and 7.0, respectively. Decreasing Langmuir K parameter and decreasing partition coefficients (K d ) with increasing pH supported this trend. Phosphorus desorption was positively affected by increased soil pH by both the total amount of P desorbed and the ratio of desorbed P to initially sorbed P. A decreased K parameter and increased K d value, particularly at the highest pH value and highest P-addition level, endorsed this phenomenon. Liming the soil had the double effect of reducing P sorption (up to 4.5 kg ha -1 of remaining P in solution) and enhancing P desorption (up to 2.7 kg ha -1 of additionally released P into solution).Index terms: liming, phosphorus bioavailability, Langmuir, partition coefficients, and Atlantic Forest.(

Air-Drying Effect on Soil Reaction and Phosphorus Extractability From Upland-Lowland Tropical Soils as Related to Their Colloidal Stability

“…Loganathan et al (1987) reported similar observation in some soils from southern Nigeria. It also seems that soil pH has pronounced influence on phosphorus availability in weathered tropical soils only under conditions of high phosphorus levels attained by addition of phosphorus solution to soil (Eze and Loganathan, 1990), or when soils are treated with liming materials to enhance normal distribution of their pH values (Sato and Comerford, 2005).…”

“…On the other hand, the relationships between soil pH and phosphorus availability have been extensively studied on tropical soils (Mokwunye, 1975;Eze and Loganathan, 1990; Sato and Comerford, 2005; among others), and some of such studies show that the low availability of phosphorus in tropical soils is often exacerbated by the acidic nature of the soils (e.g., Sato and Comerford, 2005). Yet, as with phosphorus availability, there is paucity of data about the influence of air-drying soil samples before analysis on soil reaction in tropical soils.…”

“…Soil pH influences phosphorus availability (Sato and Comerford, 2005) as well as colloidal stability of the soil (Igwe and Udegbunam, 2008). Among the soil processes known to be important in colloidal stability is alternate wetting and drying (de Oliveira et al, 2005).…”

Influência da granulometria e da mineralogia sobre a retenção do fósforo em latossolos sob pastagens no cerrado

“…Correlações positivas, negativas ou não-significativas também foram encontradas por vários autores, demonstrando efeitos complexos e, muitas vezes, antagônicos do pH sobre a sorção de P (Barrow, 1985;Geelhoed et al, 1999;Sato & Comerford, 2005).…”

Fósforo em solos representativos do estado da paraíba: I- isotermas de adsorção e medidas do fator capacidade de fósforo

“…Sua forma exponencial é Q = kC l/n , utilizada para calcular os valores n e k (Soares et al, 2006). Estudos têm relacionado a CMAP dos solos com o teor de argila e à superfície específica (Singh & Gilkes, 1991;Moughli et al, 1993;Pereira & Faria, 1998;Valladares et al, 2003;Rolim Neto et al, 2004), ao pH (Ernani et al, 1996;Pereira & Faria, 1998;Sato & Comerford, 2005), ao teor de matéria orgânica (Guilherme et al, 1993;Hepper et al, 1995;Berton & Pratt, 1997;Andrade et al, 2003;Moreira et al, 2006), ao Al trocável (Singh et al, 1983;Pereira & Faria, 1998;Falcão & Silva, 2004) e ao equivalente de umidade (Muniz et al, 1987). Estudando a adsorção de P em Latossolos com diferentes mineralogias, Motta et al (2002) constataram que não houve correlação significativa entre o teor de argila e a CMAP.…”