Plant-soil feedback is recognized as the mutual interaction between plants and soil microorganisms, but its role on the biological invasion of the Brazilian tropical seasonal dry forest by invasive plants still remains unclear. Here, we analyzed and compared the arbuscular mycorrhizal fungi (AMF) communities and soil characteristics from the root zone of invasive and native plants, and tested how these AMF communities affect the development of four invasive plant species (Cryptostegia madagascariensis, Parkinsonia aculeata, Prosopis juliflora, and Sesbania virgata). Our field sampling revealed that AMF diversity and frequency of the Order Diversisporales were positively correlated with the root zone of the native plants, whereas AMF dominance and frequency of the Order Glomerales were positively correlated with the root zone of invasive plants. We grew the invasive plants in soil inoculated with AMF species from the root zone of invasive (I ) and native (I) plant species. We also performed a third treatment with sterilized soil inoculum (control). We examined the effects of these three AMF inoculums on plant dry biomass, root colonization, plant phosphorous concentration, and plant responsiveness to mycorrhizas. We found that I and I promoted the growth of all invasive plants and led to a higher plant dry biomass, mycorrhizal colonization, and P uptake than control, but I showed better results on these variables than I. For plant responsiveness to mycorrhizas and fungal inoculum effect on plant P concentration, we found positive feedback between changed-AMF community (I ) and three of the studied invasive plants: C. madagascariensis, P. aculeata, and S. virgata.

SUMMARYBased on the assumption that silicate application can raise soil P availability for crops, the aim of this research was to compare the effect of silicate application on soil P desorption with that of liming, in evaluations based on two extractors and plant growth. The experiment was carried out in randomized blocks with four replications, in a 3 × 3 × 5 factorial design, in which three soil types, three P rates, and four soil acidity correctives were evaluated in 180 experimental plots. Trials were performed in a greenhouse using corn plants in 20-dm 3 pots. Three P rates (0, 50 and 150 mg dm -3 ) were applied in the form of powder triple superphosphate and the soil was incubated for 90 days. After this period, soil samples were collected for routine chemical analysis and P content determination by the extraction methods resin, Mehlich-1 and remaining P. Based on the results, acidity correctives were applied at rates calculated for base saturation increased to 70 %, with subsequent incubation for 60 more days, when P content was determined again. The acidity correctives consisted of: dolomitic lime, steelmaking slag, ladle furnace slag, and wollastonite. Therefore, our results showed that slags raised the soil P content more than lime, suggesting a positive correlation between P and Si in soil. Silicon did not affect the extractor choice since both Mehlich-1 and resin had the same behavior regarding extracted P when silicon was applied to the soil. For all evaluated plant parameters, there was significant interaction between P rates and correctives; highest values were obtained with silicate.Index terms: phosphorus adsorption, silicate application, liming, silicon-phosphorus interaction.( RESUMO: DISPONIBILIDADE DE FÓSFORO EM RAZÃO DA APLICAÇÃO DE CALCÁRIO E SILICATOS EM SOLOS OXÍDICOSPartindo do princípio que a aplicação do silicato pode resultar em aumento na disponibilidade de P no solo para as culturas, objetivou-se estudar a influência da silicatagem, em comparação à calagem, na dessorção de P em solos, avaliada por dois extratores e pelo crescimento da planta. O delineamento experimental utilizado foi em blocos casualizados, com quatro repetições, em esquema fatorial 3 × 3 × 5, constituído por três solos, três doses de P e quatro corretivos de acidez, além de um tratamento sem correção da acidez, totalizando 180 parcelas experimentais. O experimento foi realizado em casa de vegetação, em vasos de 20 dm 3 . Os solos foram submetidos a três doses de P (0, 50 e 150 mg dm -3 ), tendo como fonte superfosfato triplo em pó e mantidos incubados por 90 dias. Após o período de incubação, foram realizadas amostragens para análise química de rotina e determinações dos teores de P pelos métodos resina, Mehlich-1 e P remanescente. Com base nesses resultados, foi realizada a aplicação dos corretivos de acidez com as doses calculadas a fim de elevar a 70 % o valor de saturação por bases, permanecendo incubados por mais 60 dias; após, novas determinações dos teores de P foram realizadas. Os corretivos de acidez uti...

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