Potassium and silicon availability from remineralizer by composting process

As incertezas quanto a disponibilidade e preço dos fertilizantes solúveis convencionais, especialmente os potássicos, aliado à crescente necessidade de tornar a agricultura mais sustentável tem estimulado a busca por fontes alternativas de potássio (K). Nesta perspectiva, o uso de pós de rocha silicatadas, ou remineralizadores, como fonte de nutrientes tem ganhado destaque. Para melhor compreender a efetividade do processo de compostagem em melhorar a disponibilidade de K e Si de pós de rocha para o sistema solo-planta e seu impacto sobre a qualidade final dos compostos produzidos, quatro experimentos foram conduzidos. Os dois primeiros experimentos visaram analisar o efeito do enriquecimento de compostos orgânicos com pó de rocha, antecipadamente aos processos de compostagem comum e tipo bokashi sobre os teores de C, N e relação C/N. O terceiro experimento foi conduzido em casa de vegetação com as culturas de soja e milho, cultivadas em sucessão, e fertilizadas com composto comum e tipo bokashi ambos enriquecidos a 0, 5 e 10% ou misturado a 10% com pó de fonolito, buscando avaliar o efeito do processo de compostagem sobre a disponibilização de nutrientes do pó de rocha e sobre a qualidade final dos compostos produzidos. Para analisar a aplicação conjunta de pó de fonolito com composto orgânico, numa perspectiva biointempérica, sobre a produção e nutrição do capim braquiária (Urochloa decumbens), um quarto experimento foi conduzido, com aplicação de pó de fonolito in natura e composto comum (puro, enriquecido a 10% ou misturado a 10% com pó de fonolito). Os resultados evidenciaram que o enriquecimento de ambos os compostos não promoveu efeitos significativos na relação C/N quando comparado ao controle. Verificou-se que todas as fontes alternativas de K foram capazes de aumentar o conteúdo de K e Si nas plantas. No entanto, no terceiro experimento, o processo de compostagem comum se mostrou capaz de acelerar o intemperismo da rocha, resultando em maior disponibilização de nutrientes. Esta evidência abre novas perspectivas para o desenvolvimento de organominerais que aproveitem fontes silicatadas alternativas de nutrientes para a agricultura. Além disso, no quarto experimento verificou-se que aplicação conjunta de pó de fonolito com compostos orgânicos, seja como componente da mistura inicial seja como aditivo aos compostos estabilizados, é uma estratégia que aumenta a disponibilização de nutrientes da fonte mineral.Uncertainties concerning the availability and prices of conventional soluble fertilizers, especially potassium based, associated to the crescent need of making agriculture more sustainable, has stimulated the search for potassium (K) alternative sources. On this perspective, the using of silicate rock powders, or remineralizers, as nutrient source has gained importance. To better understand the composting process effectiveness in improving the K and Si availability of rock powders to the soil-plant system and its impacts over the final quality of produced composts, four experiments were set up. The first two experiments targeted to analyze the enrichment effect of organic composts with rock powders, beforehand to the common and bokashi composting processes over the C, N and C/N ratio contents. The third experiment was set up in a greenhouse with soybean and maize crops, cultivated in succession, and fertilized with common and bokashi compost both enriched at 0, 5 and 10% and mixed at 10% with phonolite powder, seeking to evaluate the composting process effect over the nutrient availability from the rock powder and over the final quality of the produced composts. To analyze the conjunct application of rock powder with organic compost, in a biointemperic perspective, over the production and nutrition of brachiaria grass (Urochloa decumbens), a fourth experiment was set up, with application of in natura rock powder common compost (pure, enriched at 10% or mixed at 10% with phonolite powder). The results demonstrated that the enrichment of both composts did not promote significant effects on the C/N ratio when compared to the control. It was verified that all alternative K sources were capable of increasing the K and Si content in plants. However, in the third experiment, the common composting process showed itself capable of accelerating the rock`s weathering, resulting in a greater nutrient availability. This evidence opens new perspectives to organominerals development which takes advantage of silicate alternative sources of nutrients to agriculture. Besides, in the fourth experiment it was observed that the conjunct application of powder phonolite with organic composts, either as an initial mixture component or additive to stabilized composts, is a strategy that increases the nutrient availability of the mineral source.Coordenação de Aperfeiçoamento de Pessoal de Nível Superio

An Evaluation of the Use of Statistical Procedures in Soil Science

ABSTRACT Experimental statistical procedures used in almost all scientific papers are fundamental for clearer interpretation of the results of experiments conducted in agrarian sciences. However, incorrect use of these procedures can lead the researcher to incorrect or incomplete conclusions. Therefore, the aim of this study was to evaluate the characteristics of the experiments and quality of the use of statistical procedures in soil science in order to promote better use of statistical procedures. For that purpose, 200 articles, published between 2010 and 2014, involving only experimentation and studies by sampling in the soil areas of fertility, chemistry, physics, biology, use and management were randomly selected. A questionnaire containing 28 questions was used to assess the characteristics of the experiments, the statistical procedures used, and the quality of selection and use of these procedures. Most of the articles evaluated presented data from studies conducted under field conditions and 27 % of all papers involved studies by sampling. Most studies did not mention testing to verify normality and homoscedasticity, and most used the Tukey test for mean comparisons. Among studies with a factorial structure of the treatments, many had ignored this structure, and data were compared assuming the absence of factorial structure, or the decomposition of interaction was performed without showing or mentioning the significance of the interaction. Almost none of the papers that had split-block factorial designs considered the factorial structure, or they considered it as a split-plot design. Among the articles that performed regression analysis, only a few of them tested non-polynomial fit models, and none reported verification of the lack of fit in the regressions. The articles evaluated thus reflected poor generalization and, in some cases, wrong generalization in experimental design and selection of procedures for statistical analysis

Nutrients release from powder phonolite mediated by bioweathering actions

Abstract Purpose Silicate 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. Method An 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. Results The 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. Conclusion Nevertheless, 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