Ademir Sérgio Ferreira de Araújo

Plant bioassays to assess toxicity of textile sludge compost

Composting of industrial wastes is increasing because of recycling requirements set on organic wastes. The evaluation of toxicity of these wastes by biological testing is therefore extremely important for screening the suitability of waste for land application. The toxicity of a textile sludge compost was investigated using seed germination and plant growth bioassays using soybean and wheat. Compost samples were mixed with water (seed germination bioassay) or nutrient solution (plant growth bioassay) at concentrations of 0, 19, 38, 76 and 152 g L-1. No negative effects were observed after five days of compost water-extract in relation to soybean and wheat seed germination. After fifteen days, under a hydroponics system, plant growth had harmful effects of the compost at concentrations above 38 g L-1. Textile sludge compost presented great phytotoxicity under hydroponics condition and the soybean and wheat were sensitive for evaluation of organic wastes in plant growth bioassays.

Effect of different tannery sludge compost amendment rates on growth, biomass accumulation and yield responses of Capsicum plants.

Composting has been recognized as one of the most cost effective and environmentally sound alternatives for organic wastes recycling from long and composted wastes have a potential to substitute inorganic fertilizers. We investigated the potential of composted tannery sludge for ornamental purposes and to examine the effects of two different composts and concentrations on ornamental Capsicum growth. The two composts were produced with tannery sludge and the composition of each compost was: compost(1) of tannery sludge (C(1)TS) - tannery sludge+sugarcane straw and cattle manure mixed in the ratio 1:3:1 (v:v:v); compost(2) of tannery sludge (C(2)TS) - tannery sludge+carnauba straw and cattle manure in the ratio 1:3:1 (v:v:v). Each compost was amended with soil at rates (% v:v) of 0%, 25%, 50%, 75% and 100% (designation hereafter as T(1)-T(5), respectively). The number of leaves and fruits were counted, and the stem length was also measured. Chlorophyll content was recorded on three leaves of each harvested plant prior to harvest. Number of leaves and fruits, stem length, dry weight of shoot and roots did not vary significantly between the plants grown in two tannery composts. All the treatments with composted tannery sludge application (T(2)-T(5)) significantly increased the number of leaves and fruits, stem length and chlorophyll content compared with the control (T(1)). The chlorophyll content was higher in plants growing in the C(1)TS compared to C(2)TS. The results of the present study further suggest that Capsicum may be a good option to be grown on composted tannery amended soil.

Sistemas agroflorestais e seus efeitos sobre os atributos químicos em Argissolo Vermelho-Amarelo do Cerrado piauiense

This study aimed to quantify the effects of agroforestry systems (AFS), with different periods of adoption, and slash and burn agriculture (SB) on the chemical attributes of an Ultisol in the Cerrado of Piaui State, Brazil. In two distinct climatic seasons (dry and rainy) four systems were studied: AFS with six (AFS6) and thirteen years (AFS13) of adoption, an area under SB and a native forest (NF), as a reference. In the AFS, in all depths, higher reduction in the Al3+ and H+ + Al3+ contents were observed as well as an increase of pH value and contents of nutrients (N, P, Ca, Mg and K) and organic carbon in soil. In the soil under SB, only in superficial layers, the ash deposited on the soil caused an increase in contents of nutrients, except for P, which was higher in all the depths. There was significant seasonal effect in the contents of nutrients, reducing in the rainy season. Agroforestry systems promoted increase in the nutrient contents of an Ultisol and can be considered useful to improve soil chemical quality in areas of Cerrado of Piaui State, Brazil.

Composto de lodo têxtil em plântulas de soja e trigo

The objective of this work was to evaluate the effect of textile sludge compost on soybean and wheat seedlings. The textile sludge compost was mixed with water plus nutritive solution, in the following concentrations (g of compost in 1,000xa0mL of water plus nutritive solution): 19xa0gxa0L-1, 38xa0gxa0L-1, 76xa0gxa0L-1 and 152xa0gxa0L-1. Axa0control, constituted of water plus nutritive solution, was included in the experiment. Axa0completely randomized design was used with four replicates. The seedlings were exposed to the concentrations of compost extract, in hydroponic system, and after 15 days, the total dry mass, height of aerial part, root length, chlorophyll content and peroxidase activity of leaves and roots were evaluated. Seedlings of both crops showed a decrease in the total dry mass, height of aerial part and root length with application of compost in concentrations equal to or above 38xa0gxa0L-1. Peroxidase activity in roots and leaves increased with the concentration of compost equal to or above 38xa0gxa0L-1. Concentrations above 19xa0gxa0L-1 of this textile sludge compost are harmfull to soybean and wheat seedlings.

Growth, nodulation and nitrogen fixation of cowpea in soils amended with composted tannery sludge

Tannery wastes generation is increasing every year and a suitable method for tannery sludge management is necessary in order to decrease this environmental problem. The composting is recognized as a suitable method for sludge recycling.. The effect of tannery sludge compost (TSC) rates on growth, nodulation and N fixation of cowpea was investigated. Sandy and clayey soils were amended with TSC at rates of 0, 7.5, 15, 30, and 60 t ha-1. The shoot dry weight of cowpea plants 45 days after emergence (DAE) was greater in the TSC-amended than in the unamended soil. In the sandy soil, nodule dry weight increased with TSC application 45 DAE. In the clayey soil, 45 DAE, nodule dry weight decreased with TSC amendment levels greater than 7.5 t ha-1 compared to the unamended control. The application of TSC increased N accumulation in the cowpea plants. The results suggest that cowpea responds differently to TSC depending on the amendment rate and initial soil type.

Soil microbial biomass in an agroforestry system of Northeast Brazil

Agroforestry systems (AFS) are considered alternative land use options to help prevent soil degradation and improve soil microbial biomass and organic C status. However, it is unclear how different densities of babassu palm [ Attalea speciosa (syn. Orbignya phalerata )], which is an important tree in Northeast Brazil, affect the soil microbial biomass. We investigated the soil microbial biomass C and activity under AFS with different densities of babassu palm associated with Brachiaria brizantha grass. Soil microbial biomass C (MBC), soil microbial biomass N (MBN), MBC:total organic C ratio, fluorescein diacetate hydrolysis and dehydrogenase activity showed highest values in plots with high density of babassu palm. On the other hand, the respiratory quotient (qCO 2 ) was significantly greater in plots without babassu palm. Brachiaria brizantha in monoculture may promote C losses from the soil, but AFS with high density of babassu palm may increase the potential of soils to accumulate C. Keywords: Enzyme activity, tropical soil, babassu palm, silvopastoral system, soil quality. DOI: 10.17138/TGFT(3)41-48

Eficiência simbiótica de isolados de rizóbio noduladores de feijão-fava (Phaseolus lunatus L.)

In tropical legumes, a careful selection of rhizobia strains, among other factors, is essential for the efficiency of biological nitrogen fixation (BNF). This selection should be made for leguminous crops of social and economic interest, such as lima bean (Phaseolus lunatus L.). The aim of this study was to evaluate the symbiotic effectiveness of rhizobia from two regions of Piaui producing lima bean. Seventeen isolates and two reference strains CIAT 899 and NGR 234 were evaluated on the fava bean genotype UFPI-468. The study was conducted in a greenhouse in autoclaved Leonard jars, in a randomized block design with three replications. Inoculation was done at planting. Samples were collected 34 days after planting to assess the following variables: shoot dry mass (SDM), root (MRS) and nodules (MNS), ratio SDM/MRS, accumulated nitrogen (Nac) in SDM by the Kjeldahl method, and N2-fixation efficiency. Significant interactions were observed among all variables except for MSR. In general, the values for DMAP, MRS , DMAP/MRS, Nac and N2-fixation efficiency of the isolates ISO-18, ISO-23, ISO-24, ISO-25, ISO-30, ISO-32, ISO-35, ISO-36, ISO-43, and ISO-45 were higher than of ISO-2, ISO-9, ISO 16, and ISO-40 and the absolute control. The variables used in this study were sufficient to discriminate and select nodulation-efficient strains for lima bean, increasing the effectiveness of BNF. Most isolates performed well in terms of N supply to plants and can be recommended for tests of agronomic efficiency.

Genetic diversity among native isolates of rhizobia from Phaseolus lunatus

The genetic diversity among native nodular rhizobia of Lima bean in soil from Piauí State, Brazil, was characterized and evaluated. The genotype UFPI-491 was used as a trap plant for rhizobia, with soil samples collected in Piaui State being used as the inoculum source. For isolation, nodules were collected at 45xa0days after seedling emergence—a period that presented the highest values for number and biomass of nodules evaluated in a previous experiment. In total, 50 isolates were obtained and placed into groups based on divergence from the morphological and physiological characterization. In general, the restriction patterns obtained with endonucleases MboI, HaeIII and NheI showed sufficient variability to discriminate between the isolates in this study. The main characteristics exhibited by isolates identified species from the genera Bradyrhizobium, Mesorhizobium and Rhizobium.

Biological Nitrogen Fixation: Importance, Associated Diversity, and Estimates

Several processes mediated by soil microorganisms play an important role in nutrient cycling. One such process is biological nitrogen fixation (BNF) by representatives of various bacterial phylogenetic groups, which are called diazotrophs. These bacteria can be free-living, associate with plant species, or even establish symbiosis with legumes. Studies with diazotrophic organisms are of great importance due to their contribution to the nitrogen supply in different ecosystems, including natural and managed systems. It is estimated that global BNF adds 122 Tg of N yearly with cultivated agricultural systems fixing from 33 to 43 Tg, which occurs mostly by legume-rhizobia symbiosis. There is a large potential of BNF contribution by associative systems with tropical grasses, but there is uncertainty in these estimates due to several assumptions in the estimation process and fewer studies with this system when compared to the legume-rhizobia symbiosis. Recent progress in the understanding of diversity, colonization ability, action mechanisms, formulation, and application of these biological systems should facilitate their development as reliable components in the management of sustainable agricultural systems. Several efforts have been made to develop commercial inoculants using these organisms. The current progress in using microorganisms that fix nitrogen in a variety of applications is summarized and discussed herein.

Inoculação micorrízica arbuscular e adubação fosfatada no cultivo de forrageiras consorciadas

EnglishThis work, carried out under greenhouse, had for objective to evaluate the response of the intercropped Stylosanthes and Andropogon grass to arbuscular mycorrhizal inoculation and levels of phosphorus in soil no sterilized (natural conditions). A randomized blocks design was used in a 4 x 3 factorial scheme (four phosphorus levels: 0, 60, 120 and 240 mg dm -3 of soil) and three microbiology treatments (control; inoculation with Glomus clarum and inoculation with native inoculum) with three repetitions. Were accomplished two cuts of the aerial part, each 60 days. It was analyzed the production of dry matter of the aerial part and root, the accumulations of crude protein, P, K, Ca, Mg, and S, percentage of mycorrhizal colonization in both plants and density of spores. The results demonstrated that the increase of the doses of P increased significantly the studied variables. Those results were evidenced with the arbuscular mycorrhizal inoculation, specially for the species Glomus clarum, mainly for the first cut. The participation of the legume in the dry matter total of the mixture was increased by the arbuscular mycorrhizal inoculation in the smallest levels of P. The mycorrhizal colonization and the density of spores were not affected by the microbiology treatments. portuguesObjetivou-se avaliar, em casa de vegetacao, a resposta do cultivo consorciado entre o capim- andropogon e o estilosantes a inoculacao com fungos micorrizicos arbusculares e aplicacao de doses de fosforo em solo nao esterilizado (condicoes naturais). Foi utilizado um Latossolo Amarelo Distrofico tipico. O delineamento experi- mental foi em blocos casualizados, num esquema fatorial 4 x 3, sendo quatro doses de P (0, 60, 120 e 240 mg dm -3 de solo) e tres tratamentos microbiologicos (controle; inoculacao com o fungo Glomus clarum e inoculacao com o inoculo nati- vo), com 3 repeticoes. Realizou-se dois cortes da parte aerea, a cada 60 dias. Analisou-se a producao de materia seca da parte aerea e raiz, os acumulos de proteina bruta, P, K, Ca, Mg e S; porcentagem de colonizacao micorrizica em am- bas as plantas e densidade de esporos. Os resul- tados demonstraram que o aumento das doses de P incrementaram significativamente as variaveis estudadas. Esses resultados foram evidenciados com a inoculacao micorrizica, com destaque para a presenca da especie Glomus clarum, principal- mente para o primeiro corte. A participacao da leguminosa na materia seca total do consorcio foi aumentada pela inoculacao micorrizica nas meno- res doses de P. A colonizacao micorrizica e a densidade de esporos nao foram influenciadas pelos tratamentos microbiologicos.