André Mundstock Xavier de Carvalho

Mycorrhizal associations in agroforestry systems

Agroforestry systems can be a viable alternative to the preservation of natural resources while contributing to sustainable food production in the tropics. These perennial systems promote beneficial biological interactions between micro-organisms and plant species, especially those formed by arbuscular mycorrhizal fungi and roots. Mycorrhizal fungi increase the soil volume explored by the roots, increase nutrient absorption by the plants, protect the root system against pathogens, toxic elements and certain heavy metals, help the formation and maintenance of soil structure, increase the input of soil carbon, and contribute to the maintenance of biodiversity. Agroforestry systems have the potential to maximize the benefits associated with AMF, which in turn could mitigate negative interactions between trees and annual crops. This beneficial impact between agroforestry management and mycorrhizal action may be depicted as a particular form of symbiosis, and deserves more study.

Atividade microbiana de solo e serapilheira em áreas povoadas com Pinus elliottii e Terminalia ivorensis

In Brazil, the species Pinus elliottii and Terminalia ivorensis are being recommended for reforestation. However, little is known about the ecological characteristics of such forests, the nutrient cycle and possible consequences on yields and sustainability under tropical conditions. For a better understanding of the C dynamic in these ecosystems, this study aimed to evaluate the microbial activity of soil, litter, and the mixture of soil + litter in forest stands of P. elliottii and T. ivorensis. Samples of soil, litter and mixture were incubated and the microbial activity was evaluated on the basis of CO2 released. At the end of incubation, the accumulated respiration was significantly higher in litter of T. ivorensis. The other substrates with litter did not differ from each other, but differed from the soil under T. ivorensis, which in turn differed from soil under P. elliottii. In the tested conditions, the soil incorporation to litter, as well as the alternate incorporation of soil from one forest with the litter of another did not cause a significant increase in litter respiration. This indicates that the influence of the chemical characteristics of the litter itself on degradation speed is stronger than the chemical and microbiological characteristics of the soil where it is incorporated.

Foliar Diagnosis Indexes for Corn by the Methods Diagnosis and Recommendation Integrated System (DRIS) and Nutritional Composition (CND)

ABSTRACT Foliar analysis has been an important method for diagnosing the nutritional status of plants. Therefore, this work aimed to determine benchmarks (norms) for interpretation of results of foliar analysis by the methods of Diagnosis and Recommendation Integrated System (DRIS) and Nutritional Composition (CND) and to determine the order of nutritional limitation and the potential response to fertilization (PRA) of corn cultivations. Leaves were sampled and the productivity was determined in 64 different sites in the crop season 2011/2012, and 66 sites were sampled in the crop season 2012/2013. The yields were divided in two sub-populations: high productivity (equal or above 11.795 kg ha−1) and low productivity (less than 11.795 kg ha−1). The normal ranges obtained by DRIS and CND methods were similar. The amplitudes of ideal ranges were smaller when compared to the sufficiency ranges found in the Brazilian literature. The development of benchmarks (norms) at regional levels increases reliability in diagnoses.

Nutrients release from powder phonolite mediated by bioweathering actions

PurposeSilicate rock powders have been appointed as possible nutrient alternative sources which might enhance the agricultural sector sustainability. However, the application of those materials directly in soil presents as main limitations the low content and solubility of the mineral nutrient sources. In this perspective, the aim of the present study was to evaluate, in a bioweathering perspective, the conjunct application potential of phonolite with organic composts over the nutrients release in soil, as well as the production and nutrition of brachiaria grass (Urochloa decumbens). In addition, it was sought to assess the composting process effectiveness in improving the nutrient release from this rock.MethodAn experiment was conducted with five treatments (control; enriched compost with powder rock at 10%; mixed compost with powder rock at 10%; solely powder rock; solely compost) and four repetitions.ResultsThe alternative sources positively influenced the productivity, as well as the K and Si contents at the aerial part of the brachiaria grass and the nutrient release in soil. However, the conjunct applications of powder phonolite with organic composts were the source which the best promoted the total nutrient biorelease to soil.ConclusionNevertheless, there was no evidence that the composting process promotes the phonolite bioweathering. On the other hand, the conjunct application of powder phonolite with organic composts, either as an initial component to the composting pile or additive to the stabilized composts, is a strategy which enhances the nutrient biorelease of the mineral source.

Rock Powder Can Improve Vermicompost Chemical Properties and Plant Nutrition: an On-farm Experiment

ABSTRACT Together with farmers, we evaluated nutrient availability from vermicomposted gneiss powder, assessed its influence on growth promotion, nutrition and heavy metal accumulation in maize plants and the effect on soil chemical properties in the field. Three soil treatments were applied: fertilization with vermicompost with gneiss powder, fertilization with vermicompost without gneiss powder, and soil without fertilization (control), in a randomized block design with five replicates. The dry weight of shoots and the concentrations of potassium, calcium, magnesium, manganese, nickel, chrome and lead in the dry matter of maize were higher with vermicompost with gneiss powder. In the soil, the potential of hydrogen and phosphorus, potassium and calcium concentrations were higher with vermicompost with gneiss. There were no detectable levels of heavy metal wastes in the soil after the experiment. We conclude that vermicomposted gneiss powder has potential for use in agriculture as a nutrient source and can improve soil chemical properties.

PROPOLIS EXTRACT IN POSTHARVEST CONSERVATION BANANA ' PRATA'

Este trabalho foi realizado com o objetivo de avaliar os efeitos do revestimento com extrato de propolis de diferentes fontes botânicas sobre as caracteristicas fisico-quimicas de banana ‘Prata’ (Musa sapientum L.), armazenada a temperatura ambiente. Bananas ‘Prata’ foram selecionadas e submetidas a cinco tratamentos pos-colheita, sendo quatro formas de revestimento por imersao em extrato de propolis de diferentes fontes botânicas com concentracao de 2,5% (m/v) (“extrato aquoso de propolis do tipo silvestre”, “extrato hidroalcoolico de propolis do tipo silvestre”, “extrato hidroalcoolico de propolis do tipo verde alecrim e “extrato hidroalcoolico de propolis do tipo vermelho ”) e um controle (sem revestimento). As variaveis avaliadas foram perda de massa, firmeza da polpa, solidos soluveis (SS), acidez titulavel (AT), relacao entre solidos soluveis e acidez titulavel (SS/AT) e potencial hidrogenionico (pH), realizadas em intervalos de 3 dias por 12 dias de armazenamento. Realizou-se a analise sensorial das bananas aos 3 e 6 dias de armazenamento, avaliadas por 55 provadores nao treinados atraves do teste de aceitacao. Ao final de 12 dias de armazenamento, os revestimentos de extrato de propolis “verde” e “aquoso” reduziram a perda de massa em banana ‘Prata’, quando comparados ao tratamento pos-colheita “controle”. Neste mesmo periodo, nao foi observado diferencas entre os tratamentos pos-colheita na firmeza da polpa dos frutos. Verificou-se a ocorrencia de menores valores de AT e maiores valores de pH em todos os tratamentos pos-colheita no decorrer do amadurecimento dos frutos. O teor de SS aumentou ao final do periodo de armazenamento, que consequentemente, contribuiu para elevar a relacao de SS/AT nos tratamentos pos-colheita, sendo mais significativo no tratamento pos-colheita “vermelho”. Sensorialmente, as bananas ‘Prata’ nao apresentaram diferencas significativas entre os tratamentos pos-colheita com e sem revestimento de extrato de propolis, apresentando caracteristicas sensoriais similares ate o 6o dia de armazenamento.