Effect of liming and phosphate application on sudangrass growth and phosphorus availability in two temperate acid soils

Abstract

A pot experiment was carried out in the greenhouse with two loamy sand Dystric Cambisols derived from schist to investigate the effect of liming and phosphorus (P) application on plant growth and P availability and its assessment by four soil test methods: 0.01M calcium chloride (CaCl 2 ), cation anion exchange membrane (CAEM), Egnér-Riehm, and Olsen procedures. Soils were first incubated for two weeks with lime at four levels, depending on their content of exchangeable aluminum (Al). Phosphorus was added at two rates (75 and 150 mg P kg -1 ) and the incubation proceeded for an additional two-week period. Sudangrass (Sorghum sudanenses cv. Tama) was then planted and harvested four weeks later. During incubation and plant growth, soils were maintained at 70% of field moisture capacity. Although pH value and soil extractable P in original soils were similar, the results showed a significant difference on the effect of liming and P application. Acidity was the major limitation for DM yield in the soil with the highest amount of 855 Downloaded by [The University of Manchester Library] at 23:40 03 January 2015 856 FERNANDES AND COUTINHO exchangeable Al, while P availability was the main constraint in the other soil. Liming above pH (0.01M CaCl 2 ) 5.3-5.5 did not increase DM yield in either soil and showed a negative effect on one soil (9.7 to 6.9 and 10.2 to 7.8 g pot -1 ). Phosphorus content and uptake by sudangrass increased with liming, revealing a positive effect of lime on the availability of P to plants. Added P showed a lower efficiency in the soil with highest amounts of Al compounds. Soil tests performed after the execution of the pot experiment showed variable tendencies to predict P availability, according to the nature of the procedures and soils. Soluble-P in 0.01M CaCl 2 increased with the rise of soil pH. Extractable CAEM-P and Egnér-Riehm-P also increased with liming, but reflected the soil depletion caused by plant uptake. Extractable Olsen-P presented the most inconclusive results, suggesting the limitation of this method for acid soils which have been limed.

Lime and cow slurry application temporarily increases organic phosphorus mobility in an acid soil

“…However, these observations could possibly be artefacts of the Olsen method. It has been suggested that Ca and P can precipitate at the increased pH (8.5) of the extract in soils with an abundant supply of Ca, such as limed soils (Sorn‐srivichai et al , 1984; Smith & Sinclair, 1998; Fernandes & Coutinho, 1999). The fact that these results were not reflected by a similar reduction in RP concentrations in soil solution suggests that they may be artefacts of the Olsen method.…”

“…Liming increases the pH in soil solution. Increased pH leads to increasingly negative charges on soil surfaces, which would tend to decrease sorption of the phosphate anion (Bolan et al , 1988; Fernandes & Coutinho, 1999). However, the composition of the soil’s CEC is also influenced by liming and has a major influence on the pH‐dependence of the P adsorption‐desorption equilibrium (Curtin & Syers, 2001).…”

Lime and Gypsum as Source Measures to Decrease Phosphorus Loss from Soils to Water

“…Morton et al (1998) and Fernandes and Coutinho (1999)). Although organic forms of P are not taken up directly by plant root systems, enzyme-labile organic P can be a large soil P pool and an important source of P for plants (Asmar et al 1995;George et al 2002;Hayes et al 2000;McDowell and Koopmans 2006;Shand and Smith 1997).…”

“…The overall effect of lime on RP solubility may depend on several competing effects of raised pH and Ca concentration that vary between soils. Generally, as pH increases, negative charges on soil surfaces also increase, leading to desorption of the phosphate anion (Bolan et al 1988;Fernandes and Coutinho 1999). Soils 1 and 2 had the largest increases in pH with liming (1.7 and 0.5, respectively), so phosphate desorption may have been responsible for increasing RP solubility in these soils.…”

The response of finely textured and organic soils to lime and phosphorus application: Results from an incubation experiment

“…The application of lime did not show a significant increase in M3 extractable P concentration in the current study, despite the large reduction in Al and Fe concentration. Increasing soil pH resulted in increased base saturation on the soil surface, thus reducing the sorption of P anions (Fernandes and Coutinho, 1999) and increasing plant available P (Ortas and Rowell, 2000).…”