Aloísio Bianchini

Crescimento da parte aérea de plantas cultivadas em vaso, submetidas à irrigação subsuperficial e a diferentes graus de compactação de um Latossolo Vermelho-Escuro distrófico

Compaction is a process that can occur in soils managed inadequately, affecting crop growth and yield directly or indirectly. The shoot development was evaluated as a function of different degrees of subsoil compaction in soybean, corn, cotton, and Brachiaria brizantha plants grown in pots filled with soil material from a dystrophic Dark-Red Latosol, with water supply through subsurface irrigation. The experiment was carried out in screened greenhouse at the School of Agronomy and Veterinary Medicine of UFMT, in rigid PVC pots with 195 mm internal diameter in a completely randomized design in a 4 × 5 factorial scheme (four species and five soil densities - 1.0; 1.2; 1.4; and 1.5 Mg m-3). The water content in the soil/pot system was maintained above 60% of its maximum water retention capacity. At the end of the experiment, the plant height was measured and the plants cut at ground level; the leaf area estimated, and cotton, corn and soybean yield and the shoot dry matter evaluated. Soil densities above 1.4 Mg m-3 led to significant reduction in the development of shoot growth of cotton, corn, and soybean, while in Brachiaria brizantha plants the reduction was verified only at a density of 1.5 Mg m-3. Soybean presented the largest increment of the evaluated characteristics at a density of 1.2 Mg m-3. Brachiaria brizantha presented higher tolerance to compaction, whereas cotton plants were the most sensitive to effects of soil compaction. In general, the quadratic model adequately explained the growth of the studied plants as a function of soil compaction.

Penetrógrafo eletrônico automático

This paper presents the development of an automatic recording penetrometer, which operates at the touch of a button. It incorporates a data acquisition system, which can store data of 187 tests and has a serial PC interface. The test characterization such as dates, location (latitude and longitude) can be recorded as well. The maximum working depth may be set and the load cell calibration can be verified through a keyboard with 2 lines display. A speed variation error of < 5% compared to ASAE standard was verified for cone indices between 500 and 5,684 kPa. The equipment is compact, easy to handle and can realize one test every minute.

Comportamento da palha de cana-de-açúcar submetida ao corte por meio de ensaios de bancada

From an engineering standpoint, few papers on crop residue shearing have been published, especially with respect to sugarcane and information on the subject is scarce. Therefore, the objective of this work was to study the behavior of sugarcane trash submitted to shearing, as a function of its moisture content, thickness of trash layer and the oblique angle of the blade. A strength transducer, connected to the base of the blades and to an automatic data logger, was utilized to collect data, working at an acquisition rate of 9600 Hz. Results showed significant differences in the required strength when the oblique angle of the blade is changed, and a linear trend with the amount of trash between 4 and 16 t ha-1. The strength requirement and the energy demand showed an exponential behavior with changes in moisture content of sugarcane trash. For moisture content above 28% (dry basis), the differences between required shearing strengths and energy demands were no longer significant. The maximum shearing strength showed a linear trend which was inversely proportional to the oblique angle of the blade.

Correlation of the least limiting water range with soil physical attributes, nutrient levels and soybean yield

and micronutrients analyzed, and also with the land slope, compared the correlation with the soybean yield data. Therefore, nutritional analysis of the grains complemented by physical analysis of the soil can be used to identify nutritional imbalances that are not otherwise observable and thus, the LLWR can be useful for planning corrective actions regarding soil and crop management, based on measurement of the Bdcritical.

Soil chiseling and fertilizer location in sugarcane ratoon cultivation

While the pre-harvest sugarcane burning is a disused practice, green harvest requires changes concerning ratoon cultivation due to the presence of a thick layer of straw. The experiment, conducted in a mechanical green harvesting area cultivated with sugarcane, consisted of two stages: in the first stage, the mechanical straw cutting performance of flat disks with different geometry edges was evaluated, considering two types of disks and 10 replications in a completely randomized design; in the second stage, the effect of soil chiseling on both sides of planting lines, using shanks with straw cutting flat disks, was assessed, as well as fertilizer deposition form. The experimental design in the second stage was completely randomized, with seven treatments and five replications. Treatments consisted of a combination of two straw cutting disks (smooth or toothed edge), chiseling presence or absence, and fertilizer deposition forms (broadcast, on the planting line, and incorporated into chiseling furrows). The toothed disk differed from the smooth one, presenting lower values of horizontal and vertical forces, and torque. The agroindustrial variables pol (%), brix (%), fiber (%), and ATR (kg Mg-1) were not influenced by the fertilizer deposition form and soil chiseling. However, the localized fertilizer deposition increased crop yield when compared with broadcast fertilization.

Evaluation of cotton stalks destroyers

The destruction of the cotton crop residues (cotton stalks) is a mandatory procedure in Brazil for prophylactic issues, but is a subject unexplored by the research and there are few studies that deal with this issue. However, this is not encouraged in recent decades, studies aimed at developing and evaluating equipment for this purpose. The present study had the objective to evaluate six methods for mechanical destruction of cotton crop residues. Each method was defined based on the principle of operation of the active parts of the equipment, which were tested in medium texture soil and in a clayey one. The variables used to evaluate the efficiency of the equipment were the regrowth rate, the theoretical field capacity and energy demand. The equipment with convergent concave disks (DCC) and flat cutters discs from manufacturer A (CPS-a) showed the best results in cotton stalks destruction in both soil types. The harrow disc (GPD) was efficient only in clay soil. It was concluded that the equipment with convergent concave disks, among those tested, was the most efficient to destroy cotton stalks, regardless of soil type, and that the harrow disc was not included among the best performers.

Demanda tractiva en función de la resistencia mecánica del suelo a la penetración

In this study, empirical models were developed to determine the tensile force demanded by disc plows, harrows and planters fertilizers, as function of soil mechanical resistance to penetration. The mean of the referred resistance was determined until 25, 35 and 15 cm depths, according to the regulations for the disc plow, springs harrow and fertilizer seeder. The adjustment was verified based on the coefficient of determination, dispersion graphics, residual analysis and t test (Student). It was confirm the normality of the residuals and to establish intervals of confidence with 95% of probability. The estimated and experimentally obtained values did not differ significantly. It was concluded that the associated exponential functions presented appropriate precision and reliability to predict the traction force being considered the soil mechanical resistance to penetration and that the models can be a useful tool for planning and management of mechanized farming operations in soils with texture similar to those of this research.