Uilka E. Tavares

Desenvolvimento e acúmulo de macronutrientes em plantas de milho biofertilizadas com manipueira

Objetivou-se, neste estudo, avaliar o desenvolvimento vegetativo e o acumulo de macronutrientes em plantas de milho submetidas as doses de manipueira. O experimento foi conduzido em ambiente protegido no periodo de marco a maio de 2011. O delineamento experimental foi inteiramente casualizado em esquema fatorial 2 (tipos de solo: franco-arenoso e franco-argiloso) × 4 (doses de manipueira: 0; 11,2; 22,4 e 44,8 m3 ha-1), com oito repeticoes. As variaveis analisadas foram: altura das plantas, diâmetro de colmos, numero de folhas, materia fresca e materia seca da parte aerea das plantas e teores de N, P, K, Ca e Mg no tecido foliar. O aumento das doses de manipueira elevou o conteudo de massa fresca, o teor de nitrogenio e potassio da parte aerea das plantas, mas diminuiu a altura das plantas e o teor de magnesio na parte aerea das plantas. Os acrescimos de materia seca e de calcio na parte aerea das plantas foram maiores no solo franco-arenoso.

Variabilidade espacial de atributos físicos e mecânicos de um Argissolo sob cultivo de cana-de-açúcar

The purpose of this study was to evaluate the spatial relation of physical and mechanical attributes of a cohesive Ultisol cultivated with sugarcane. Forty nine georeferenced points were established for the collection of samples, with 7 x 7 grid, forming a mesh of 120 x 120 m. The trenches were opened at two layers (0-20 and 20-40 cm) for the collection of disturbed and undisturbed samples. The normal distribution was observed in all variables. Strong degree of spatial dependence was also observed for most variables. The plastic limit showed nugget effect. The highest range was found for the liquid limit (0-20 cm) compaction degree (0-20 cm) and lowest for soil moisture (0-20 cm), IP and organic carbon (20-40 cm). Kriging maps showed an inverse correlation between density and porosity and strong correlation between clay and organic carbon as well as between the clay and the limits of consistence. For most variables, there was spatial dependence up to 20 m, indicating that for parametric analysis, samples should be collected at distances over 20 m.

Spatial Dependence of Physical Attributes and Mechanical Properties of Ultisol in a Sugarcane Field

This study investigates the effect of conventional tillage and application of the monoculture of sugar cane on soil health. Variables like density, moisture, texture, consistency limits, and preconsolidation stress were taken as indicators of soil quality. The measurements were made at a 120 × 120 m field cropped with sugar cane under conventional tillage. The objective of this work was to characterize the soil and to study the spatial dependence of the physical and mechanical attributes. Then, undisturbed soil samples were collected to measure bulk density, moisture content and preconsolidation stress and disturbed soil samples for classification of soil texture, and consistency limits. The soil texture indicated that soil can be characterized as sandy clay soil and a sandy clay loam soil, and the consistency limits indicated that the soil presents an inorganic low plasticity clay. The preconsolidation tests tillage in soil moisture content around 19% should be avoided or should be chosen a management of soil with lighter vehicles in this moisture content, to avoid risk of compaction. Using geostatistical techniques mapping was possible to identify areas of greatest conservation soil and greater disturbance of the ground.

Community structure and spatial variability of soil nematodes in an alluvial soil in a semiarid region of Pernambuco state, Brazil

Caatinga, a biome of deciduous dry forest and shrub vegetation, predominates in the semiarid northeastern region of Brazil. In this dry biome, research on soil nematode community structure and spatial distribution is scarce but helpful to address soil management. In this work the spatial variability of nematode communities was studied in relation to soil properties. Plant-parasitic nematodes (PPN) was the dominant trophic group followed by bacterivores, omnivores, fungivores and predators. PPN positively correlated with both soil coarse sand and water content, whereas omnivores and bacterivores negatively correlated with coarse sand and clay fraction, respectively. Despite differences in density, omnivores, bacterivores and fungivores were quite similar in spatial patterns. The low dominance of Dorylaimidae (0.64%) and the high dominance of PPN (84.53%) indicates a high level of human intervention in the experimental plot.