Variabilidade espacial e temporal dos atributos físicos do solo cultivado com cana-de-açúcar sob práticas de mecanização

Abstract

Brazil stands out in the cane industry as the world's largest producer of sugarcane. The state of Pernambuco occupies the seventh place in the national ranking and, in the Northeast, it acts as the second largest producer of this region. However, some practices adopted by the plants, especially those associated to the use and mechanized management of cohesive soils, prevent a better prominence in the sugarcane industry. The continuity of unsuitable practices in the mechanized management of the soil consortium to the water deficit directly influences the modification of the soil characteristics, mainly in its physical attributes. In this sense, precision farming techniques, such as geostatistics, are currently used to help improve soils and thus promote high yields to producers. In this way, the objective of the present work is to evaluate the spatial and temporal variability of the physical attributes of the soil in relation to the mechanization practices. The study was conducted at the Experimental Station of Sugar Cane of Carpina (EECAC-UFRPE), where a grid was delineated with intervals of 10 m, making a total of 49 georeferenced points, at the depths of 0-0.30 m and 0.30 -0.60 m. Three collections were carried out over a year, the first one being carried out six months after the use of the subsoiling (T6), the second collection after 12 of the subsoiling, but with the disc harrow + furrow opener+ planting (T12) and the last collection performed after 18 months of the first mechanized management, but where sugarcane was already close to harvest (T18). The soil resistance to field penetration and soil moisture during the test were evaluated; soil density; the pore network of the soil and subsequent construction of the soil water retention characteristic curve (SWRCC); Index S; the saturated hydraulic conductivity and the tensile strength of the soil. All data were submitted to descriptive statistics, mean test and geostatistics. The results indicated that the management performed in T6 and T18 presented the best results regarding the physical quality of the soil, and there was no cumulative effect of management techniques for T12. The geostatistical technique indicated that most of the attributes presented a degree of spatial dependence varying from strong to moderate, attributes such as soil density and humidity showed a pure nugget effect, and it is necessary to increase the sample mesh. In this sense, it is evident that after six months of the use of the subsoil (T6) and the effect of the root system of the sugarcane in T18, they worked in the improvement of the physical quality of the soil, being, therefore, the negative effects promoted by the management in T12, it is suggested that it should not be carried out, only subsoiling being practiced and then, through the furrower, the planting is carried out.