Luiz Guilherme Medeiros Pessoa

Produtividade de alface com doses de esterco de frango, bovino e ovino em cultivos sucessivos

The aim of this work was to evaluate the use of three types of animal manure: poultry, cattle and sheep manure on lettuce production in a field experiment in an Oxisol, at the Federal Agro Technical School, in Crato, Ceara State, Brazil. The experimental design used was randomized blocks with factorial arrangement [(3 x 5) + 2], with three manures, five doses, and two additional Treatments, the first one with chemical fertilizer and the second one the control (without fertilizer), with four replications. The following variables were evaluated: fresh and dry matter of plant, yield ha-1 and number of leaves plant-1. The poultry manure provided higher yields of lettuce in the first crop, however, after the second crop it was surpassed by the cattle and sheep manures. The largest doses of the manure provided high yields until the third crop, being necessary new application for the maintenance of good results. The chemical fertilizer promoted high yields only until the second crop, being necessary a new application for the third crop.

Physical attributes of soil under different uses with irrigation in semiarid Pernambuco

Soils in semiarid climate regions had been degraded by salinization, reducing their productive capacity. This work aimed to evaluate physical attributes of soil in an irrigated perimeter in the semiarid Northeast of Brazil and to compare different soil uses using these attributes. The study was carried out at Ico-Mandantes Irrigated Perimeter, between Petrolândia and Floresta, in semiarid region of Pernambuco, in which the populations were separated by their uses in annual crops (C), fruticulture (F), discarded lands (D), pasture (P), native vegetation (V). Undisturbed and disturbed soil samples were collected, in layers of 0-10, 10-30 and 30-60 cm, for physical analysis. The indicators were submitted to multivariate analysis, by Principal Component Analysis, and clustering by the Tocher method. The agricultural use promoted alterations in the physical attributes of soil in relation to soil under native vegetation. The soil quality for the physical attributes varied between the layers of 0-10 and 10-30 cm, except in use V, sohich presented similar quality in these layers. F and P uses had presented better physical soil quality than C use in the layers of 0-10 and 10-30 cm and D use presented the worst soil quality in the evaluated layers.

Spectral Reflectance Characteristics of Laboratory-Grown Salt Crusts on Silty Clay and Sandy Soils

Salinization of soils has led to the loss of cropland and represents a major threat to food production. Hyperspectral imaging may prove to be useful for characterizing the spectral behavior of salt-affected soils but the methodology needs to be better evaluated. In this study, we characterized the spectral behaviors of four types of chloride salt crusts [calcium chloride dehydrate, magnesium chloride dehydrate, potassium chloride, and sodium chloride (CaCl2·2H2O, KCl, and NaCl)] formed in the laboratory. We found that (1) as salt concentration increased, the reflectance intensity decreased for both soil types, and the decreases were especially pronounced for the soils leached with the CaCl2·2H2O and MgCl2·2H2O solutions; (2) soil texture had little if any effect on reflectance; and (3) reflectance intensity decreased in the order CaCl2·2H2O < MgCl2·2H2O < KCl < NaCl. By clarifying the spectral behavior of chloride salt crusts on soils, our work demonstrates hyperspectral imaging may differentiate some types of salts and determine relative salt concentrations.

Spectral reflectance characteristics of soils in northeastern Brazil as influenced by salinity levels

In northeastern Brazil, large swaths of once-productive soils have been severely degraded by soil salinization, but the true extent of the damage has not been assessed. Emerging remote sensing technology based on hyperspectral analysis offers one possibility for large-scale assessment, but it has been unclear to what extent the spectral properties of soils are related to salinity characteristics. The purpose of this study was to characterize the spectral properties of degraded (saline) and non-degraded agricultural soils in northeastern Brazil and determine the extent to which these properties correspond to soil salinity. We took soil samples from 78 locations within a 45,000-km2 site in Pernambuco State. We used cluster analysis to group the soil samples on the basis of similarities in salinity and sodicity levels, and then obtained spectral data for each group. The physical properties analysis indicated a predominance of the coarse sand fraction in almost all the soil groups, and total porosity was similar for all the groups. The chemical analysis revealed different levels of degradation among the groups, ranging from non-degraded to strongly degraded conditions, as defined by the degree of salinity and sodicity. The soil properties showing the highest correlation with spectral reflectance were the exchangeable sodium percentage followed by fine sand. Differences in the reflectance curves for the various soil groups were relatively small and were not significant. These results suggest that, where soil crusts are not present, significant challenges remain for using hyperspectral remote sensing to assess soil salinity in northeastern Brazil.

Improvement of degraded physical attributes of a saline-sodic soil as influenced by phytoremediation and soil conditioners

ABSTRACT This study aimed to evaluate the use of phytoremediation and soil conditioners in the recovery of physical attributes of a saline-sodic Fluvic Neossol in Brazil Northeast. The applied treatments were: Atriplex nummularia L., as phytoremediation plant, due to its ability to extract salts from the soil; organic conditioners, such as bovine and sheep manure; gypsum and polymer, as chemical conditioners. Samples with preserved structure were collected at the time of the experiment installation and 18 months after in the layers 0–10 cm and 10–30 cm. The analyzed attributes were: water dispersed clay, dispersion index, bulk density, penetration resistance, soil porosity, and saturated hydraulic conductivity. The use of sheep manure, gypsum and polymer promoted an increase in saturated hydraulic conductivity in the 0–10 cm layer from 4.51 to 16.37 cm day−1, 11.26 to 23.95 cm day−1 and 7.24 to 22.77 cm day−1, respectively. Gypsum increased the macroporosity in the superficial layer by 42.6%. Atriplex and polymer were more efficient at reducing soil penetration resistance. The polymer was more efficient at improving the physical properties. However, it is necessary to consider phytoremediation with Atriplex as a more sustainable alternative that can still be used as complementary fodder in animal feed.

Chemical attributes of an Ultisol under different management systems in a humid tropical climate

Agricultural use of land normally changes soil properties, depending on soil management and climatic conditions. Aiming to analyze the chemical modifications of an Ultisol, this study was conducted to evaluate the soil chemical attributes when submitted to cassava planting and fallow condition and how it compares to the natural ecosystem in the region (Atlantic Forest). Soil samples were collected at depths of 0-0.20 and 0.20-0.40 m for chemical analysis of soil characterization. Most of the chemical attributes did not differ between the systems at any depth, with the exception of K in the cassava system with contents of 0.72 cmolc kg at the depth of 0-0.20 m and 0.57 cmolc kg at the depth of 0.20-0.40 m. The Atlantic Forest showed the highest values of P (34.61 mg kg) and total organic carbon (2.31 dag kg) at the depth of 0-0.20 m, which was significantly differing from the other systems. The period of 1 year fallow adopted to recover the productive capacity of the soil was not sufficient for the studied area. With the removal of the forests for implantation of the agricultural system (cassava) there was a marked reduction in the levels of organic carbon and phosphorus in the soil at the depth of 0-0.20 m. Key-words: Agricultural Land Use, Fallow Land, Cassava, Atlantic Forest

Erratum to: The effects of two preservatives on peroxidase activity and total protein content in Strelitzia reginae during cold storage

This study aimed to assess changes in peroxidase activity and total protein content of cut flowers of Strelitzia reginae that were treated with the chemical preservatives 8-hydroxyquinoline citrate (8-HQC) or chlorine during cold storage. The bases of the cut flowers were immersed in 1.5 L of tap water with 48 h pulsing treatments (a control with no chemical preservatives (0 mg·L-1, 100 mg·L-1 chlorine, 250 mg·L-1 8-HQC or 500 mg·L-1 8-HQC) during cold storage at 10.5°C and 90% relative humidity. The solutions were then replaced with tap water and the cut flowers remained in cold storage for 12 days. For biochemical characterization of peroxidase activity and total protein content, tissue samples (sepals, petals, stems, and bracts) were collected and analyzed at 0, 4, 8, and 12 days after treatment. There was an increase in peroxidase activity in petals, stems, and bracts and a decrease in total protein content, regardless of the treatment used. In this experiment, therefore, differences in peroxidase activity and total protein content due to treatments with 8-HQC or chlorine were not identified.