Distribution of P Forms in Natural and Fertilized Forest Soils of the Central Western Spain: Plant Response to Superphosphate Fertilization

Abstract

Soil responds dynamically to the addition of phosphates by establishing exchanges among the di †erent reservoirs of P existing in the soil. T he aim of this work was to Ðnd out the e †ects of surface applied fertilization with triple superphosphate at two concentrations (50 and 100 kg P ha ] 1 ) in soils of the Sierra de Gata mountains (Spanish Central System) on forms of soil P, the availability of P for plants, and the impact on aboveground production of the tree cover and grasses. Soil P was deter ± mined according to Hedley, and P availability was quantiÐ ed using ion exchange membranes. T he e †ects of P fertilization on P forms were observed mainly in the Ðrst 10 cm of the study soils ; there were no signiÐcant di †erences at greater depths because of the high P sorption capacity of these soils. W ith a moderate fertilization of 50 kg P ha ] 1 only two of the four studied soils showed a signiÐcant increase in labile P contents and of P adsorbed by sesquioxides. An intense fertilization (100 kg P ha ] 1 ) had signiÐcant e †ects on the distribution of soil P, independently of the initial available P of soils. However, fertilization with triple superphosphate did not signiÐcantly a †ect the aerial production of the tree cover (except in the Ðrst year), whereas it did a †ect herbaceous production at two sites, possibly because they have a larger root mass near the soil surface.

31P-NMR characterization of phosphorus fractions in natural and fertilized forest soils

“…The distribution of P among different organic and inorganic forms reflects the history, present structure, and function of an ecosystem [15,32].…”

Evolution of forest soil properties after liming with a by-product derived from a sugar beet mill

“…The standard deviations for the rest of the parameters are lower and the significant differences observed in the limed subplot in relation to the no-limed one should be attributed to the effect of liming (except for the available P, given that availability of P is also influenced by other soil properties, as the soil pH, inputs of organic residues, and/or the presence of free sesquioxides [15].…”

“…It was previously demonstrated that the soil sesquioxides (Fe and Al) quickly precipitated the dissolved P [34,35,40,15]; as a result of this, it is not possible to improve the availability of soil P with the sole addition of liming material. Komljenovic et al [41] found that liming influenced the annual production yields, but so did the climatic factors; given the low dissolution process of the CaCO 3 added, it is difficult to think that the dissolved liberated Ca 2+ could have more impact than the sesquioxides.…”

“…It is well known that when the soil pH is lower than 4.0, Mn 2+ and Al 3+ cations exist in soluble forms [11], increasing their plant availability and causing toxicity, inhibiting forest growth [12]. Furthermore, other works [13,14,15] showed the lack of response of these forests to the addition of N and P fertilizers.…”

Sequestration of C in a Spanish chestnut coppice

“…Furthermore, rainfall and runoff (slopes frequently higher than 30%) permit that acidif ication remains in these deciduous forest ecosystems (Gallardo et al, 1998b;Moreno & Gallardo, 2002). In addition, in spite that the decomposition of litter (Table 2) is relatively fast, the N is retained by the decomposing litter (Gallardo et al, 1998b), the P availability by plant is very low (Turrion et al, 2000), and the stability of the humic substances (calculated soil-humus decomposition-constant is 0.026, Table 3) is high.…”