Biocarvões como condicionadores do solo e seus efeitos sobre o crescimento e a nutrição de Eucalyptus urograndis
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Data
2020-04-30
Autores
Santos, Danilo Andrade
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Universidade Federal do Espírito Santo
Resumo
The State of Espírito Santo – Brazil – has, within its agrarian production, materials that are generated in great volume and with the potential to be used for energy conversion and consequent production of biochars to return to the field as soil conditioners. In this research three studies are presented in order to understand how biochars affect the soil structure, the availability of nutrients and the nutrition and development of eucalyptus plants. In the first chapter, the objective was to evaluate the availability of P and K in macro and microaggregates of the soil, formed from the addition of doses of biochars of different granulometries, obtained in two pyrolysis temperatures in samples of a Oxisol. The experiment was conducted in a laboratory, under a randomized block design in a controlled environment with a temperature of ± 25ºC, for a period of 119 days. The experimental test was arranged in a factorial scheme (2 x 4 x 4) + 1, with three replicates and an additional treatment. The factors under study were: coffee straw biochars produced from two final pyrolysis temperatures, 350 and 600ºC; four doses of biochars, corresponding to 10, 20, 40 and 80 t ha-1; four particle sizes of biochars (2,0-1,0 mm; 1,0-0,5 mm; 0,5-0,25 mm; 0,25-0 mm); and additional treatment without adding biochars. In the second chapter, the objective was to evaluate the effects on aggregation and stability of aggregates promoted by the addition of increasing doses of biochar of different granulometries, produced from Conilon coffee straw, in a Oxisol, after 119 days of incubation, using the aggregates obtained, after dry screening, in the experiment of the first chapter. Thus, at 119 days of incubation, the aggregates were evaluated in dry and wet separations, and from the data obtained in both separation methods, the aggregation indexes, geometric mean diameter (DMG) and average diameter were studied. weighted (DMP), and also calculated the aggregate stability index (IEA) for macroaggregates (> 0,25 mm) obtained by dry process and sieved in wet process. In the last chapter, the objective was to evaluate the effect of applying doses of eucalyptus bark biochar produced under two carbonization temperatures on the chemical attributes of the soil, initial development and nutrition of eucalyptus plants. (Eucaliptus urograndis). A field trial was established with a 2 x 5 factorial scheme: two pyrolysis temperatures (350 and 600 ° C) and five doses of biochar (0; 0,25; 0,5; 1 and 2% v/v). At 365 days, the following chemical soil analyzes were performed: pH, Al, Ca, Mg, Na, K, H + Al, total organic carbon, total nitrogen and COT and NT stocks, in two depths: 0-10 and 10-30 cm. At 180 and 365 days after planting, biometric data on height and stem diameter of the plants were obtained, and at 365 days leaf sampling was performed for leaf nutrient analysis. In the first chapter, it was found that conilon coffee straw biochars, regardless of the final pyrolysis temperature, dose and granulometry increase the availability of P and K in macro and microaggregates of the soil, reaching the order of 5 times the K values considered suitable for most cultures, with the lowest dose of biochar. For P, availability increased between 100% and 600%. The highest availability of P in macroaggregates was found for treatments under biochar of 600 ºC and the highest availability of P for microaggregates was achieved for treatments under biochar of 350 ºC. It was found that K has a higher availability in both soil aggregates, under 600 ºC biochar. The joint action of granulometry and / or effects in aggregation, promoted by biochars, tends to develop higher levels of K in macroaggregates, regardless of the temperature at which the biochars were produced. Biochars of 600 ºC and of greater granulometry provide greater contents of P available in the macroaggregates, whereas biochars of smaller granulometry, regardless of the temperature of production of the biochar, promote greater availability of phosphorus in the microaggregates. In the second chapter, it was found that the pyrolysis temperature of 600 ºC promoted greater soil aggregation (6%), observed by the higher values of DMG and DMP, in relation to 350 ºC, in the aggregates separated by dry route. However, in the wet way, no differences were observed between pyrolysis temperatures on aggregation. Soil aggregation tended to be favored in treatments that received biochars smaller than 0,25 mm at 350 ºC, and 0,25-0,5 mm at 600 ºC. The stability of the dry macroaggregates tends to be lost when in the presence of water by the dissolution of materials, which acted as cement, which possibly had been precipitated in the aggregates, obtained by sieving through dry. The loss in stability of macroaggregates in the presence of water occurs in the sense of increasing the temperature and granulometry of biochars. In the third chapter, it was found that the effects on the chemical attributes of the soil in eucalyptus cultivation were identified in the levels of total nitrogen and nitrogen stock, without, however, showing a pattern of behavior depending on the treatments studied. Nutritional enrichment in the eucalyptus culture was identified for the levels N and K, in treatments under 600 ºC biochars, and the effect of reducing the Zn levels due to the increase in the doses of biochars. There were no significant effects on the biometrics of eucalyptus plants. The results obtained, for the Eucaliptus and treatments tested, indicate the need for a more extensive experimental period to better assess the effects on soil attributes and plant nutrition and development.
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Matéria orgânica carbonizada , Nutrição mineral de plantas , Fertilidade do solo