Resumo A reabilitação de campos agrícolas abandonados é uma tarefa multidisciplinar, que busca o desenvolvimento de sistemas produtivos sustentáveis. O objetivo deste estudo foi avaliar o efeito da técnica de microtopografia e condicionadores de solo na sobrevivência, crescimento e nutrição de Eucalyptus saligna de uma área agrícola abandonada. Parcelas de microtopografia e parcelas planas foram estabelecidas em um campo agrícola abandonado (27º 12.08' S e 49º 07.60' W). Dentro das parcelas, subparcelas com plantas foram estabelecidas e receberam a aplicação de condicionadores de solo, que incluíram fonolito (100 g), inoculante micorrízico (200 cm3), lodo de celulose e casca de arroz carbonizada (200 cm3), fonolito (100 g) e inoculante micorrízico (200 cm3) e controle. O experimento foi monitorado entre novembro de 2013 e outubro de 2014 e parâmetros de crescimento foram mensurados após 30, 90, 150, 210, 270 e 330 dias do início do experimento. De cada planta, foram mensuradas altura, diâmetro do caule e área da copa. Ao final do experimento, 50 folhas de cada planta foram coletadas para determinar a concentração de fósforo e potássio. A comunidade micorrízica nativa foi caracterizada por um bioensaio e as espécies identificadas a partir de esporos coletados em campo. Taxas de sobrevivência de Eucalyptus saligna tenderam a ser mais altas em parcelas de microtopografia. Altura da planta, diâmetro do caule, área da copa e concentração de P e K na biomassa foram significativamente maiores em plantas em parcelas de microtopografia. Condicionadores do solo influenciaram significativamente a concentração de K na biomassa. A aplicação da técnica de microtopografia melhora a sobrevivência, crescimento e nutrição de Eucalyptus saligna e representa uma importante estratégia para reabilitar áreas agrícolas abandonadas.

Abstract Rehabilitation of abandoned agricultural fields is a multidisciplinary task, in pursuit of the development of sustainable productive systems. The objective of this study was to evaluate the effect of microtopography technique and soil conditioners on survival, growth and nutrition of Eucalyptus saligna of an abandoned agriculture field. Plots of microtopography and flat plots were established in an abandoned agriculture field (27º 12.08' S and 49º 07.60' W). Within plots, we stablished subplots with plants, which received the application of soil conditioners, including phonolite (100 g), mycorrhizal inoculant (200 cm3), pulp sludge and carbonized rice husk (200 cm3), phonolite (100 g) and mycorrhizal inoculant (200 cm3) and control. The experiment monitoring occurred between november 2013 to october 2014 and growth parameters were measured after 30, 90, 150, 210, 270 and 330 days of the experiment onset. From each plant, height, stem diameter and canopy area were measured. At the end of the experiment, 50 leaves were collected from each plant to determine potassium and phosphorus concentrations. The native mycorrhizal community was characterized by bioassay and species identification of field-collected spores. Survival rates of Eucalyptus saligna tended to be higher in microtopography plots. The Plant height, stem diameter, canopy area, and shoot P and K concentration were significantly higher in plants at microtopography plots. Soil conditioners influenced significantly the shoot K concentration. The application of microtopography technique improved survival, growth, and nutrition of Eucalyptus saligna, and it represents an important strategy to rehabilitate abandoned agricultural fields.

ABSTRACT: The production of tree seedlings with high survival rate and growth is influenced by the substrate, which may be composed of biological and non-biological materials that help plant growth. The objective of this study was to evaluate the efficiency of a mycorrhizal inoculant on farm and the use of a potassic rock (phonolite) on growth and nutrition of Eucalyptus saligna Sm. and Schinus terebinthifolius Raddi under greenhouse conditions. Both species were assigned to three mycorrhizal treatments [no inoculated control (SP), no inoculation + pulp sludge and carbonized rice husk (LC), and mycorrhizal inoculant (IN)] and four phonolite rock treatments [no phonolite (F0) and addition of phonolite in particle sizes of 0.037 mm (F1), 0.074 mm (F2), and 0.149 mm (F3)]. The IN treatment consisted of inoculum of Claroideoglomus etunicatum (Becker & Gerd.) C. Walker & A. Schussler (isolate MGR288A) and Dentiscutata heterogama (Nicol. & Gerd.) Sieverd. F.A. Souza & Oehl (isolate PNB102A) produced on farm with pulp sludge and carbonized rice husks. After 120 days, plants were evaluated for height, stem diameter, shoot and root dry weight, shoot K and P, and mycorrhizal colonization. Growth parameters were used to calculate the Dickson Quality Index (DQI) for seedlings. Growth parameters of S. terebinthifolius demonstrated synergistic and positive effects when different particle sizes of phonolite and on-farm mycorrhizal inoculum were used together. For E. saligna, phonolite and on-farm mycorrhizal inoculum had little effect on growth parameters, although the mycorrhizal inoculum increased K and P content in the F0 and F2 treatments. The DQI of S. terebinthifolius was higher with IN compared to SP and LC with phonolite, whereas this index was not influenced by most treatment combinations for E. saligna. Overall, the percentage of mycorrhizal root colonization for both species was significantly higher when phonolite was present in the substrate. The interaction of mycorrhizal inoculum produced on farm and phonolite rock has the potential to increase growth and nutrition of S. terebinthifolius and E. saligna.