Maria Leonor Ribeiro Casimiro Lopes-Assad

Eficiência da produção de cana‑de‑açúcar em duas safras no Estado de São Paulo

A conceptual framework for crop production efficiency was derived using thermodynamic efficiency concept, in order to generate a tool for performance evaluation of agricultural systems and to quantify the interference of determining factors on this performance. In Thermodynamics, efficiency is the ratio between the output and input of energy. To establish this relationship in agricultural systems, it was assumed that the input energy is represented by the attainable crop yield, as predicted through simulation models based on environmental variables. The method of FAOs agroecological zones was applied to the assessment of the attainable sugarcane yield, while Instituto Brasileiro de Geografia e Estatistica (IBGE) data were used as observed yield. Sugarcane efficiency production in Sao Paulo state was evaluated in two growing seasons, and its correlation with some physical factors that regulate production was calculated. A strong relationship was identified between crop production efficiency and soil aptitude. This allowed inferring the effect of agribusiness factors on crop production efficiency. The relationships between production efficiency and climatic variables were also quantified and indicated that solar radiation, annual rainfall, water deficiency, and maximum air temperature are the main factors affecting the sugarcane production efficiency.

Release of potassium from rock powder by the yeast Torulaspora globosa

The alteration of minerals in rocks and the availability of elements for plant nutrition require long periods of time, and microorganisms are thought to induce the release of potassium and phosphate from rocks. In this context, this work evaluates the role of the yeast Torulaspora globosa, isolated from the sugar cane rhizosphere, in the solubilization of potassium from alkaline ultramafic rock powder. The experiments were performed in liquid medium, with or without agitation, at 30°C with the following treatments: culture medium + alkaline ultramafic; culture medium + yeast suspension; and culture medium + yeast suspension + alkaline ultramafic. The results showed that as much as 38% of the total potassium in the rock was released in the medium with the yeast during a 15-day period of incubation. Acid production may be the mechanism by which the yeast solubilizes potassium because the total acidity increased during the sampling period. Agitation (which increased oxygen availability) resulted in approximately 20% more biosolubilization of the alkaline ultramafic rock than with the static culture. These data indicate the potential for this yeast in biosolubilization processes and biofertilizer production.

Simulação do efeito do manejo da palha e do nitrogênio na produtividade da cana-de-açúcar

The objective of the study was to model the growth and productivity of green and burnt sugarcane harvesting systems, under three nitrogen fertilizer levels (60, 120 and 180 kg ha-1). APSIM-Sugar crop model was previoulsy calibrated based on two field experiments conducted in Piracicaba,SP and Salinas, MG, with the cultivar SP80-1842. The sensitivity of the model was evaluated for the parameters of soil and variety, especially those related to the soil organic matter dynamics and nitrogen. The model simulated well the sugarcane growth and yield in the evaluated environments. Simulations showed that sugacarne yield being highly dependent on trash management. Trash removal from fields would ultimately decrease the crop yield. Simulations also revealed that the nitrogen doses as high as 180 kg ha-1 would not be enough to overcome the yield lost due to trash removal.

Effect of rock powder and vinasse on two types of soils

Can vinasse accelerate the change of minerals in rock dust to obtain fertilizers, using residues from alcohol agro-industries and mining? Answering this question was the main objective of this study. Therefore, an experiment was set up in the laboratory in a completely randomized design using Polyvinyl Chloride (PVC) columns, in which the 0-50 cm layers of a clayey soil (eutroferric Red Oxisol) and sandy soil (Typic Quartzipsamment) were reproduced. We applied three different rates of basalt powder (0.0; 2.0, and 4.0 t ha-1) and one rate of vinasse (200 m3 ha-1) to the soils. The control was made by treatments with water (200 m3 ha-1) with the same rates of rock powder. Samples were first collected on the surface of each column (1, 15, 30, 45, 60, and 90 days after the application of vinasse and rock powder), and, at the end of the experiment, at the various depths and in leached water, to determine pH and the concentration of soluble Ca2+, Mg2+, and K+. There was a significant effect of the solvent and the soil on the surface layer, with higher concentrations found in the treatments with vinasse and in clayey soil, confirming the potential of vinasse to alter minerals in basalt powder. The resulting levels from the beginning to the end of the experiment suggest that sorption phenomena with neoformed mineral phases or organic acids may have occurred. It may be concluded that the use of rock powder and vinasse mixtures is a promising alternative for soil fertilization and recycling of waste from the sugarcane and mining industries.

A Hydrophysical Database to Develop Pedotransfer Functions for Brazilian Soils: Challenges and Perspectives

Access to soil hydrological data is vital for hydrology projects and for supporting decision-making in issues related to the availability of food and water and the forecasting of phenomena related to geomechanics. Brazil is a country of continental dimensions and has accumulated a significant body of soil information, holding a prominent position in tropical soil science. Nevertheless, a database with hydrophysical information on Brazilian soils has not been compiled so far, whereas much information is registered and analyzed. In this study we discuss the potential for the development of a Brazilian hydrophysical database and pedotransfer functions (PTFs). We present on metadata the measurement methods of soil hydrophysical attributes and the characteristics of the sites where these soil properties were determined. Statistical analyses were performed to characterize the dataset according to the metadata-based data structure. A total of 8,983 datasets contains soil water retention information associated with physical or chemical properties. Besides these, 1,253 datasets with data on saturated hydraulic conductivity coupled with water retention information are also available. The results of this study suggest that it is possible to develop a representative hydrophysical database for Brazilian soils that covers most of Brazil’s federative states, with a substantial volume of data and homogeneous with respect to the methods of measuring soil properties. This creates excellent prospects for PTFs development, especially for estimating water retention, at a national scale. The challenge in the development of the Brazilian soil hydrophysical database is the refinement of the dataset model that can encompass the wide range of available information and can provide answers to queries of interest to different types of users of soil information. Considering the size of the Brazilian territory, it would be of interest that the database development become a joint effort of government agencies, universities and commercial enterprises.

Identificação de padrões de erros em estimativa de densidade do solo

O objetivo deste estudo foi analisar e interpretar os padroes nos erros de quatro funcoes de pedotransferencia (PTF), desenvolvidas para estimar a densidade do solo (DS), utilizando a tecnica de inducao de arvore de decisao (AD). O conjunto de dados usado era composto por 974 amostras de solos de diversos biomas do Brasil e continha informacoes sobre granulometria (areia, silte e argila), teor de carbono (C) e pH. Os dados de granulometria foram reclassificados em classes de textura. A primeira PTF foi desenvolvida no conjunto de dados utilizado neste trabalho e as tres outras, selecionadas na literatura, foram geradas para diferentes locais. A selecao das tres PTFs foi feita com base nos atributos preditores utilizados, sendo necessario que todos estivessem presentes no banco de dados utilizado. Na avaliacao, foram adotados limiares de 0,08 g cm -3 , 0,1 g cm -3 e 0,12 g cm -3 para definicao de erros aceitaveis e erros nao aceitaveis. Quatro valores de poda (minimo de objetos nas folhas de 5%, 10%, 15% e 20%) foram testados buscando obter melhor desempenho das ADs. As arvores geradas foram consistentes para os diferentes valores de limiar de erro e coeficiente de poda. As ADs foram semelhantes, para uma mesma PTF, independente do limiar utilizado. A PTF Benites apresentou a maior taxa de sensitividade (83,3%), com a maior taxa de erros classificados como aceitaveis e que realmente eram aceitaveis. As PTFs apresentaram padrao nos erros e foi possivel detecta-los utilizando AD.

Solubilization of diabase and phonolite dust by filamentous fungus

Este trabalho objetivou avaliar o efeito do fungo Aspergillus niger, linhagem CCT4355, na liberacao de nutrientes contidos em pos de dois tipos de rocha (fonolito e diabasio), por meio de ensaios de solubilizacao in vitro. O delineamento experimental foi o inteiramente casualizado, em esquema fatorial 5x4, com tres repeticoes. Foram avaliados cinco tratamentos (po de fonolito + meio; po de fonolito + fungo + meio, po de diabasio + meio, po de diabasio + fungo + meio e fungo + meio) e quatro epocas de amostragens (0, 10, 20 e 30 dias). Adicionou-se po de rocha (0,4% m/v) a Erlenmeyers de 125 mL, com 50 mL de meio de cultura liquido adaptado para A. niger. Os frascos foram incubados a 30 °C, por 30 dias, e foram feitas analises de pH em agua, acidez titulavel e teores de potassio, calcio, magnesio, zinco, ferro e manganes soluveis. O A. niger foi capaz de produzir acidos orgânicos que solubilizaram ions. Este resultado indica o potencial de A. niger para alterar minerais contidos em pos de rocha, com capacidade de interagir de diferentes formas com os nutrientes. Houve aumento significativo da quantidade de K soluvel, no tratamento com po de fonolito, em presenca do fungo. Conclui-se que a linhagem CCT4355 de A. niger pode solubilizar minerais contidos nesses pos de rochas.