Danilo Dufech Castilhos

Rendimentos de culturas e alterações químicas do solo tratado com resíduos de curtume e crômio hexavalente

This study was carried out in order to evaluate yields of wheat, lettuce and radish, as well as chemical changes in an Oxisoil due to the addition of tannery waste and hexavalent chromium. Microplots in a greenhouse, which consisted of 60 L plastic pots, received the following treatments: control; lime + NPK; primary tannery sludge + PK; chrome-tanned leather shavings + lime + NPK; finished leather shreds + lime + NPK; Cr6+ + lime + NPK; Cr6+ + lime + cattle manure; lime + cattle manure. The sludge contained 8.5 g kg-1 Cr and was applied at rates of 8.8 t ha-1. The leather shavings contained 17.1 g kg-1 and the shreds, 19.4 g kg-1 Cr. These wastes were applied at rates of 4.4 and 3.8 t ha-1, respectively. The Cr6+ (K2Cr2O7) and the cattle manure rates were 100 mg kg-1 and 20 t ha-1, respectively. Tannery sludge plus PK increased the soil pH (5.1 to 5.8), the soil N (1.26 to 1.51 g kg-1), and the soil Ca (4.1 to 5.9 cmolc dm-3) .Wheat, lettuce and radish yields in this treatment were similar to the ones obtained with lime plus NPK. Chromium concentrations in the soil and crops cultivated with tannery sludge varied from 40.7 to 71.2 and from 0.08 to 2.71 mg kg-1, respectively. These values were considered normal. Additions of chrome-tanned leather shavings and finished leather shreds did not decrease the crop yields or change Cr concentrations in soil or plants. Cr6+ applications caused an intoxication of the plants which provoked a yield drop in wheat and lettuce of 91 and 86 %, respectively, in comparison to lime plus NPK. The toxic effect of Cr6+ decreased when cattle manure was added.

Acetylated rice starches films with different levels of amylose: Mechanical, water vapor barrier, thermal, and biodegradability properties

Biodegradable films from native or acetylated starches with different amylose levels were prepared. The films were characterized according to the mechanical, water vapor barrier, thermal, and biodegradability properties. The films from acetylated high amylose starches had higher moisture content and water solubility than the native high amylose starch film. However, the acetylation did not affect acid solubility of the films, regardless of the amylose content. Films made from high and medium amylose rice starches were obtained; however low amylose rice starches, whether native or acetylated, did not form films with desirable characteristics. The acetylation decreased the tensile strength and increased the elongation of the films. The acetylated starch-based films had a lower decomposition temperature and higher thermal stability than native starch films. Acetylated starches films exhibited more rapid degradation as compared with the native starches films.

Distribuição e caracterização de substâncias húmicas em vermicompostos de origem animal e vegetal

The use of organic residues as fertilizers and soil conditioners requires their maturation and the quality monitoring of the final product. Vermicomposting is a technique which, along with the composting process, eliminates the potential harmful effect of manure residues to human health and soil. The stability and maturity degrees of a given vermicompost are usually inferred from the quantity and quality of the humic substances in the resulting compost. This study aimed to evaluate the quality and maturity of vermicomposts from six different residues: cattle manure (CM), sheep manure (SM), pig manure (PM), quail manure (QM), coffee dregs (CD) and mate-tee dregs (MD), by determining the content of humic substances (humic, HA, and fulvic acids (FA) and their chemical composition, after 70 days of composting. The humic substances were chemically fractionated according to their solubility in basic and acidic medium. The distribution of total C in the different humic fractions was determined, and the humification indices HA percentage and HA/FA ratio were calculated. The elemental composition (CHNO) and chemical composition by infrared spectroscopy (IRSP) were determined in the purified HA and FA. An aromaticity index (I1630/I2920) was calculated based on the IRSP spectra. The vermicomposts differed in humic substance content (FA+HA), which decreased in the order CD > SM ≈ MD ≈ CM > PM > QM. The maturity degree was greater in the vermicomposts of vegetal residues (coffee and mate-tee dregs). The HA showed that the proportion of O containing functional groups and the aromatic degree were lowest in these two vermicomposts.

Atributos microbianos do solo após a adição de lodo anaeróbio da estação de tratamento de efluentes de parboilização do arroz

Rice, grown in all Brazilian regions, is particularly important in the southern region, where 60 % of the total production of this cereal is raised. The rice parboiling process is a hydrothermal treatment of partially cooking the grains in the husk, improving the nutritional value. This process results in an effluent rich in organic matter and nutrients, which can be used as organic fertilizer in agriculture. In this sense, this study aimed to evaluate the quality of a soil based on changes of some microbial properties arising from the addition of anaerobic sludge from an effluent treatment plant of parboiled rice. Two experiments were conducted. The first in a greenhouse, with corn grown on an Ultisol enriched with anaerobic sludge of parboiling rice at doses of: 2.15; 4.31; 8.62; 12.93; and 17.24 g kg-1. Soil organic carbon and nitrogen and the microbial biomass were evaluated. The second experiment was developed in the laboratory using respirometric vessels with the same soil and treatments as in the previous experiment; the microbial activity was determined by basal respiration. Soil without fertilization and NPK fertilized soil constituted control treatments. Treatments were arranged in a completely randomized design with four replications. The sludge increased soil microbial activity, and the carbon and nitrogen contents of the microbial biomass, and decreased the soil metabolic quotient. Sludge application did not affect the ratios COT/NT, CM/NM, CM/COT and NM/NT in comparison to the NPK treatment. Sludge increased the contents of soil organic carbon and caused a decrease in the levels of mineral N (NH4+ and NO3-), compared to the NPK treatment. The sludge originated from rice parboiling can be applied to soil at the recommended doses, with benefits for the microbial activity and biomass.

ATRIBUTOS DO SOLO E CRESCIMENTO DO MILHO DECORRENTES DA ADIÇÃO DE LODO ANAERÓBIO DA ESTAÇÃO DE TRATAMENTO DE EFLUENTES DA PARBOILIZAÇÃO DO ARROZ

The residue of the process of parboiling rice contains high amounts of elements such as nitrogen, phosphorus and others which, once incorporated into the soil, could serve as a source of nutrients. Accordingly, the present study evaluated some properties of an Ultisol, the dry matter production and nutritional status of corn grown after applying an anaerobic sludge originated from the process of parboiling rice. The experiment was conducted in 4 kg pots filled with soil, in four replications. The following treatments were studied: control, NPK fertilization, 2.15, 4.31, 8.62, 12.93, and17.24 g kg-1 sludge. Sludge application from parboiled rice increased the maize dry matter yield, as well as pH, electrical conductivity and the concentration of N, P, K and Na in the soil. The sludge also increased the concentration of N, P and K and decreased Ca and Mg in the maize shoots.

Atributos químicos e biológicos de um solo de várzea afetados pela sistematização do terreno

The objective of this work was to evaluate the relationship between soil chemical and biological attributes and the magnitude of cuts and fills after the land leveling process of a lowland soil. Soil samples were collected from the 0 - 0.20 m layer, before and after leveling, on a 100 point grid established in the experimental area, to evaluate chemical attributes and soil microbial biomass carbon (MBC). Leveling operations altered the magnitude of soil chemical and biological attributes. Values of Ca, Mg, S, cation exchange capacity, Mn, P, Zn, and soil organic matter (SOM) decreased in the soil profile, whereas Al, K, and MBC increased after leveling. Land leveling decreased in 20% SOM average content in the 0 - 0.20 m layer. The great majority of the chemical attributes did not show relations between their values and the magnitude of cuts and fills. The relation was quadratic for SOM, P, and total N, and was linear for K, showing a positive slope and indicating increase in the magnitude of these attributes in cut areas and stability in fill areas. The relationships between these chemical attributes and the magnitude of cuts and fills indicate that the land leveling map may be a useful tool for degraded soil recuperation through amendments and organic fertilizers.