Ivandro de França da Silva

Sistemas de cultivo e características do solo afetando a estabilidade de agregados

This research was carried out in Rio Grande do Sul State, Southern Brazil, during the 1990/1991 summer harvest. The main objective was to evaluate the aggregation and aggregate stability of two clayey soils classified as Dusky Latosol (Haplorthox) and Dark-Red Podzolic (Paleoudult). Two treatments were used in the Haplorthox: grass (Setaria anceps L.); and crop rotation under conventional tillage (wheat (Triticum aestivum) soybean (Glycine max L.)). On the other hand, four treatments were used in the Paleoudult: grass (Digitaria decumbens L.), leguminous (Macroptilium atropurpureum L.), crop rotation under no-tillage (oat (Avena bizantina) corn (Zea mays)) and bare soil. Soil aggregation and aggregate stability were greatly enhanced through the action of the grass roots. Soil aggregation was also related to the contents of organic carbon, oxalate-extractable iron and aluminum, clay and water-dispersed clay. However, these factors were not sufficient to explain differences observed in the weighed mean diameter of soil aggregates among the treatments.

Avaliação de métodos de determinação de água disponível e manejo da irrigação em terra roxa sob cultivo de algodoeiro herbáceo

This study was conducted in greenhouse conditions at the DSER/CCA/UFPB, located in Areia, PB, Brazil. The main objective was to evaluate two methods of determination of available soil water, a direct method (DM) and a laboratory method (LM), and the effect of three levels of available water, 10, 25 and 40% as indicative of irrigation management in cotton crop (Gossypium hirsutum L. r. latifolium Hutch). A completely randomized block was utilized in a 2 x 3 factorial scheme, with three replications. The variance analysis showed that the values of the available soil water using the direct method were significantly (p < 0.01) higher than the laboratory method. The management of irrigation in the cotton crop using 40% of available water by DM, showed better results of evapotranspiration, leaf area and above ground biomass. Interaction of methods versus levels of available water for all variables studied was also found.

Avaliação quantitativa e qualitativa da fitomassa de leguminosas para uso como cobertura de solo

Twelve species of tropical legumes (Crotalaria juncea L, Cajanus cajan L, Cajanus cajan (L) Millsp, Calopogonium mucunoides L, Canavalia ensiformis L, Dolichos lab lab L, Pueraria phaseoloides L, Macroptilium atropurpureum L, Leucaena leucocephala L, Clitoria ternatea L, Styzolobium aterrimum L, Styzolobium cinereum Piper and Tracy) was evaluated for use as green manure or cover crops in an experiment in Alagoinha-PB, Brazil. The used experimental design was a ramdomized complete block design, with 12 treatments in plots of 20m2, with three repetitions .The largest biomass quantities were produced for Leucaena leucocephala, Cajanus cajan, Styzolobium aterrimum, Pueraria phaseoloides, Canavalia ensiformis and Clitoria ternatea, while Crotalaria juncea, produced the smallest biomass. The biomass of Pueraria phaseoloides, was shown with better quality for the incorporation.

Efeito de leguminosas nas características químicas e matéria orgânica de um solo degradado

With the purpose of evaluating the effect of leguminous crops on the chemical characteristics of a degraded Alfisol, in the municipal district of Alagoinha, PB, Brazil, an experiment was conducted during 1997-99 with twelve species: Crotalaria juncea L, Cajanus cajan L, Cajanus cajan (L) Millsp, Calopogonium mucunoides L, Canavalia ensiformis L, Dolichos lab lab L, Pueraria phaseoloides L, Macroptilium atropurpureum L, Leucaena leucocephala L, Clitoria ternatea L, Styzolobium aterrimum L, and Styzolobium cinereum Piper and Tracy besides a control treatment. In this study, the soil of the experimental site did not receive mineral fertilizer nor any corrective. The chemical characteristics of the soil were evaluated at 0-10, 10-20 and 20-30 cm depths. The results showed significant effects of the leguminous crop on the fertility of the soil, in comparison to control, with significant increments of pH and of exchangeable bases, reflecting positively in CEC and in the base saturation. In the organic matter, there was no significant effect among the leguminous crops and control.

Influência de doses de fósforo no fluxo difusivo em solos de Alagoas

The effect of distinct doses of phosphorus was evaluated on the diffusion of this element in soil samples from the State of Alagoas. The experiment was performed in the laboratory of the Centro de Ciencias Agrarias of the Federal University of Alagoas, Rio Largo, AL. The soils were classified as a compacted Yellow Latossol, Grey Argissoil, Fluvic Neosoil, Quartzanic Neossoil and ortic Chromic Luvissoil. Chemical, physical and mineralogical analyses had been made. The determination of the remaining P was made in the equilibrium solution. The maximum capacity of adsorption was determined through the remaining phosphorus, using PVC rings which were used as diffusion chambers. The doses of phosphorus had been equivalent to 0, 10, 20 and 30% of the maximum capacity of adsorption. The evaluation of the diffusive flow of phosphorus in the soils was carried out through papers of anionic exchange, using filter-papers saturated with the iron oxide. The experiment was constituted of a factorial arrangement (6 x 4), corresponding to six soils and four doses of phosphorus. The most sandy soils and the largest dose always showed the largest diffusive fluxes of phosphorus.

Amostragem para avaliação da fertilidade do solo em função do instrumento de coleta das amostras e de tipos de preparo do solo

The measures of the average and variability of soil fertility indexes can vary with the sampling tool and soil tillage type. Soil sampling methods must be developed that are more reliable to represent the real conditions of soil fertility. This study aimed at an evaluation of the effects of the cutting shovel and hand auger on measures of average and variability of the soil fertility index (a) under no-tillage (NT) and conventional tillage (CT), (b) to estimate the minimum number of simple samples to form a composite sample and (c) to test the hypothesis that the arithmetic average of simple samples is equal to the result of the chemical analysis of the composite sample. Chromic Luvisol samples were collected in a control experiment of soil tillage type, planted with corn. In a 81 m2 plot under NT 48 simple soil samples were collected, 24 with a cutting shovel (perpendicularly to the furrow and in-between two furrows) and 24 with auger hole, in controlled sampling (four samples collected in the planting furrow, 8 to 10 cm away from the furrow and 12 in-between the furrows), close to the points of sampling with the cutting shovel. The procedure was repeated in a second plot under CT. Composite samples of different numbers of simple samples (4, 8, 12, 16 and 24 simple samples/composite samples), with three repetitions were prepared for each combination of soil tillage type - collection tool. The pH and the contents of P, K+ Ca2+, Mg2+ and organic matter (OM) were determined in all simple and composite samples. The variability of the evaluated characteristics in samples collected with auger hole was greater than with the cutting shovel, independent of the soil tillage type. For both collection tools, the decreasing order of variability was: P > Mg2+ > K + > Ca2+ > OM > pH. The medium fertility of a field under NT or under CT after the crop and before subsequent soil preparation can be evaluated with the auger hole, substituting the cutting shovel, if the composite sample consists of 17 % of simple samples collected in the planting furrow, 33 % at a distance of 10 cm from the furrow and 50 % in the middle between the furrows. The mean fertility of a field under NT or CT after the crop and before the subsequent soil preparation, evaluated by the chemical analysis of the composite sample, is similar to that evaluated by the arithmetic average of the chemical analyses of the simple samples collected with cutting shovel or with auger hole in a controlled manner, as used here. In general, a minimum of eight simple samples collected with cutting shovel or hand auger would be enough to form a representative composite sample for evaluation of the soil fertility of a unit of seemingly homogeneous sampling. However, the higher the number of collected simple samples, the more reliable or accurate is the medium fertility estimate.

Gramíneas e leguminosas na recuperação de áreas degradadas: efeito nas características químicas de solo

Com o objetivo de avaliar a eficiencia de duas leguminosas e duas gramineas na melhoria das caracteristicas quimicas do solo (carbono orgânico, CTC efetiva e potencial e teores de P, K, Na, Ca, Mg, H + Al e pH do solo), considerando a profundidade e a posicao de coleta das amostras, foi realizado experimento com arranjo fatorial em parcelas subdivididas, utilizadas anteriormente para estudos de perdas de solos por erosao, em um Nitossolo Vermelho eutrofico textura argilosa, localizado no municipio de Alagoinha (PB). Os tratamentos utilizados constituiram-se de duas leguminosas (feijao guandu - Cajanus cajan L. e siratro - Macroptilium atropurpureum L.), duas gramineas (capim-pangola - Digitaria decumbens L. e capim-elefante - Pennisetum purpureum L.) e parcela desnuda (testemunha), com tres repeticoes. A utilizacao das leguminosas e das gramineas promoveu aumentos nos teores de carbono orgânico total e na capacidade de troca de cations; promoveu, tambem, aumento nos teores de potassio, materia orgânica e magnesio, principalmente na camada superficial. O maior acumulo de liteira foi conseguido com o capim-elefante, sendo este acumulo maior na posicao inferior das parcelas em todos os tratamentos.

Caracterização etnopedológica de Planossolos utilizados em cerâmica artesanal no Agreste Paraibano

Classic ethnoscientific techniques were adapted to describe and analyze the knowledge of peasant potters about soils they use for making pottery in a rural village in the Agreste region, State of Paraiba, northeastern Brazil. Five soil profiles from pits where local people obtain pottery clay were formally described by researchers (etic approach) and by peasant artisans (emic approach). Samples collected during both the emic and etic approaches were used for the morphological and analytical soil characterization. The peasant potters were able to distinguish, identify, and name soil materials arranged in layers along the soil profiles, somehow comparable to the arrangement of the pedogenetic horizons. Vision, touch and taste are used by local potters to evaluate the quality of pottery clay. Among the soil profiles described near clay pits, four were classified as Haplic Solonetz, and one as Eutric Planosol, according to the FAO/UNESCO legend. Ethnopedological studies in different social and pedological environments could contribute to the advancement of soil science and are an opportunity for an improvement in the understanding and appreciation of soil knowledge and management by peasant potters.

Varabilidade temporal da precipitação pluvial: nível de nitrogênio no solo e produtividade de cultivares de girassol

With the aim of analyzing the effects caused by temporal variability of rains over sunflower (Helianthus annuus L.) tillage income and development in function of nitrogen fertilization and cultivars, experiments with sunflower tillage were performed in Alagoinha-PB in the years of 1995,1996,1998 in the municipal district of Esperanca-PB in 1998. In this occasion four levels of nitrogen were verified (0, 30, 60 and 90kg.ha-1), two cultivars (one precocious and another late) in blocks at random with four repetitions. Beyond these experiments, some data about pluvial precipitation were analyzed. During the performance of the experiments we analyzed the tillage phenological stages, biomass accumulation and income and its components. In relation to the results, was verified in Alagoinha-PB an annual average rains of this period (1981 - 1999) around 1.018,6mm. The sunflower vegetative and reproductive stages have changed according to the distribution of rains during the tillage cycle. The adopted treatment answers for tillage over the analyzed variations were depending on the distribution of rains during the tillage development stages. There was also a big variation in the tillage answers in relation to the nitrogen levels and in the cultivars in function of weather.

Mudas de oiticica irrigadas com águas salinas no solo com biofertilizante bovino e potássio

An experiment was carried out during the period of March to July of 2012 in the Agrarian Science Center of Federal University of Paraiba, Areia, Paraiba State, Brazil, in order to evaluate the initial growth of Licania rigida plants by height, stem diameter, leaf area, total chlorophyll content and biomass of the roots and of the aerial parts of the plants as function of water salinity and bovine biofertilizer and with potassium in the soil. Treatments were arranged in entirely randomized design, with six replicates, in factorial scheme 5 x 2 x 2, corresponding to waters with electrical conductivity of 0.5; 1.5; 3.0; 4.5 and 6.0 dS m-1 in soil without and with 300 mL of bovine biofertilizer applied one time on soil surface, and without and with 1.4 g of potassium chloride. The increment of salinity in irrigation water inhibited the growth and the quality of the seedlings, but with more loss in plants of the treatments without bovine biofertilizer and without potassium chloride. The plants cultivated in soil with potassium showed better growth in relation these of the treatments without the mineral fertilizer.