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Conservaçäo da natureza e recursos da terra
Contém ref. bibliográficas
Contém referências bibliográficas
Contém referências bilbiográficas
The phytoavailability of soil phosphorus (P) depends on the different forms in which it occurs and how these forms change after the application of P fertiliser to the soil. Forms of P in the A, B and C horizons of
eleven pedons that developed on mafic rocks were characterised by a fractionation method before and after fertilisation with single superphosphate, and a micropot experiment was conducted to assess the shortterm
use of P fertiliser by rye (Secale cereale L.). The main sources of P to the crop were (i) phosphate adsorbed on mineral surfaces and pedogenic Fe, Al or Ca phosphates in the A horizon and (ii) Ca-phosphates in B and C horizons. In the C horizons, poor in Fe/Al phases and clay, the precipitated Ca-P showed low solubility, resulting in a reduction in shot biomass. The apparent P recovery by rye was similar in the A (36%) and B
(29%) but decreased in the C (15%) horizons. The partial factor productivity (g g−1) decreased from the A (58) to B (11) and C (5) horizons. P phytoavailability decreased with increasing profile depth because the
transformation of P fertiliser to poorly soluble Ca-P forms increased with depth.
Despite the high prevalence of canine Leishmania infantum infection in Portugal, significant differences associated with different risk factors can be found between geographically contiguous areas. In this study, a geographical area within the central region of Portugal (municipalities of Proença-a-Nova, Mação and Vila de Rei) was investigated. An epidemiological survey involved the analysis by an indirect enzyme-linked immunosorbent assay of serum samples collected during the anti-rabies vaccination campaign from 282 dogs. Geospatial analysis showed the distribution of geospatial prevalence of leishmaniosis and has delimited two areas (clusters) with a statistically significant higher risk of seropositivity in dogs (p = 0.003 and p = 0.027, for clusters 1 and 2, respectively). The highest seroprevalence (56.0%; CI: 41.2-70.0) was found in Vila de Rei. Five land occupation types showed a possible influence on the geographic distribution of seropositivity, with statistically significant differences between seropositive and seronegative dogs. Land occupied by temporary irrigated crops (p = 0.026), olive groves (p = 0.013), complex cultural systems and parcelling (p = 0.021), open forests, logging and new plantations (p = 0.043) and watercourses (p = 0.012) influenced the geographical distribution of canine Leishmania infection. Seropositive dogs had a greater average area of occupied land (i.e. open forests, logging and new plantations) than the seronegative ones (3.1439 km2 versus 2.5650 km2, respectively; p = 0.043).
