Biocarvões de palha de café e os atributos do solo, desenvolvimento inicial e nutrição do cafeeiro conilon
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Data
2019-02-28
Autores
Alvarenga, Anarelly Costa
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Universidade Federal do Espírito Santo
Resumo
Coffee is the main agricultural activity in Espírito Santo, being of economic and social relevance to the state. However, during this activity a large volume of by products is generated, especially coffee straw. Proper disposal of this residue is one of the biggest challenges for coffee growing, as it is forbidden to apply fresh coffee straw to the soil. One of the options is to transform coffee straw into biochar, since their addition promotes improvements in the chemical, physical and biological properties of the soil and, consequently, favoring plant development. The objective of this work was to evaluate the effects of the use of conilon coffee straw biochar on the chemical and biological attributes of the soil and also on the initial development and nutrition of conilon coffee. Intuition experiments were carried out under various environmental conditions (field, greenhouse and laboratory). Chapter 1 aimed to evaluate the effects of coffee straw biochar on soil organic matter components. For this, experiments were performed under field and laboratory conditions. The experiment under field conditions was carried out at the Federal Institute of Espírito Santo (IFES), with a 2 x 5 factorial distribution, two conilon coffee straw biochar (two pyrolysis temperatures, 350 and 600 °C) and five doses of these. Biochar applied to the coffee pit: (0.00, 1.5, 3.0, 4.5, 6.0 dm3 ). The experiment under laboratory conditions at the Center of Agrarian Sciences and Engineering of the Universidade Federal do Espírito Santo in a randomized block design (DBC) with five replications. The treatments corresponded to a 2x5 factorial, being the factor 1: the coffee straw biochar produced at two pyrolysis temperatures (350 and 600 ° C); factor 2: coffee straw biochar in 5 doses (0, 5, 10, 15 and 20 t ha-1 ). The results showed that biocarbons did not cause changes in biomass C content and soil microbial activity under field conditions. Pyrolysis temperature had no influence on the oxidizable carbon fractions under field conditions, but there was a dose effect (dm3 ) for labile oxidable carbon fractions, F1 and F2, and for non-labile carbon fractions, F3, in the 0-10 cm from the ground. The use of 6.0 dm3 of biochar in the coffee pit promoted increases of 50 and 70% in the carbon values of labile oxidable fractions, F1 and F2, respectively. For the nonlabile oxidizable carbon fraction, F3, the volume of 4.5 dm3 increased the contents of this fraction by 61%. In the 0-10 cm depth of the soil there was influence of the pyrolysis temperature on the soil TOC contents, where biocarbons produced at 600 ° C promoted a 48% increase in the TOC contents. Regardless of the carbonization temperature, the volume of 4.5 dm3 promoted the increase of 46% in TOC contents in the 10-20 cm soil layer. The results obtained from these studies prove that conilon coffee straw biocarbons are efficient in rapidly increasing soil TOC contents. On the other hand, it was observed that under laboratory conditions, treatments with 600 °C biochar and standardized pH values had a negative effect on soil microbial activity at all doses. Chapter 2 aimed to evaluate the effect of coffee straw biocarbons on soil chemical attributes and initial development of conilon coffee under field conditions. The experiment was carried out at the Instituto Federal do Espírito Santo (IFES), with a 2 x 5 factorial distribution. Two biocarbons of conilon coffee straw (pyrolysis temperatures, 350 and 600 °C) and five doses of these biocarbons, applied to the pit. of coffee: (0.00, 1.5, 3.0, 4.5, 6.0 dm3 ). Coffea canephora Pierre, Robusta Tropical variety (EMCAPER 8151) was used as an indicator plant. The experiment was conducted for 240 days. Among the evaluated variables, the ones that stood out were the high K contents in pits with biochar application, regardless of the pyrolysis temperature. The use of 6.0 dm3 of coffee straw biochar increased the available soil K contents in the depth of 0-10 cm by 140 mg dm3 . A similar result was observed in the depth of 10-20 cm of soil in which there was an increase of 158 mg dm3 of K with the use of 6 dm3 of biochar in the coffee pit. These increases in soil K contents are caused by the ashes present in the biochar. These materials, regardless of pyrolysis temperature, also promoted increases in soil Ca and Mg contents at 0-10 cm depth. Only biochar produced at 350 °C promoted increases in Cu concentrations in the 0-10 cm soil layer, which was directly proportional to the applied dose, with an increase of 53.5% in the highest dose. The lack of effect of biochar on the initial development and nutrition of coffee may be related to the low capacity of coffee straw biochar to provide macro, except K, and micronutrients to the soil. Chapter 3 aimed to evaluate the effects of increasing doses of coffee straw biochar on the chemical attributes of soil, initial development and nutrition of conilon coffee, (Coffea canephora Pierre, clone 02.) under controlled conditions, greenhouse. Treatments corresponded to a 2x5 factorial, two biochar of coffee straw (pyrolysis temperatures of 350 600 °C); and five doses of each biochar (0; 5; 10; 15 and 20 t ha-1 ). The experimental period began with the planting of seedlings, lasting 180 days. Regardless of pyrolysis temperature, increasing doses of coffee straw biochar promoted progressive increases in soil P and Mg contents. The increase in available P concentrations may be related to the release of humic substances by the biochars. These compounds have functional groups, such as the carboxylic and phenolic groups, that block the phosphorus adsorption sites, increasing the availability of this nutrient in the soil. The increase in available soil K contents was directly proportional to the applied biochar doses, with the highest increases observed when using the biochar produced at 600 ° C. Doses close to 15 and 20 t ha-1 of the coffee straw biochar produced at 600 ° C and 350 ° C, respectively, raise the available soil K content above 200 mg dm3 , which is sufficient to supply the initial demand for this nutrient for the Conilon coffee seedlings. However, it is noteworthy that it is the ashes present in biochar that are responsible for the increase of K concentrations in the soil. Increasing biochar doses up to 10 t ha-1 promoted an increase in plant height and leaf dry mass and total dry mass values. Plants that developed in soils with the addition of biochar produced at 350 ° C had higher leaf dry mass and total dry mass and, consequently, accumulated higher N, K, Fe, Mn contents.
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Palavras-chave
Biochar , Coffee-growing , Plant residues , Condicionador do solo , Cafeicultura , Resíduos vegetais , Plant nutrition