Desenvolvimento inicial da cultura da soja em área com sistemas de rotação de culturas

Abstract

To meet the condition of being the largest soybean producer in the world today, Brazilian agriculture needs to optimize its processes, always aiming at increasing its productivity levels, that is, producing more and more in the same area. To guarantee satisfactory results in the harvest, correct seeding is essential, and a good technique is direct planting in straw, which can generate a better plant development start. However, when talking about direct planting, it should be remembered that crop rotation is part of the constitution of this planting system, which in turn deposits a layer of vegetative cover on the soil from previous crops, which, when mismanaged, can cause difficulties in cutting the plant material, generating planting failures. Due to this, the present study aimed to evaluate the longitudinal distribution of soybean seedlings subjected to different crop rotation systems. At the experimental farm of the Federal University of Grande Dourados, fifteen days after soybean implantation, a field collection was carried out with the aid of a measuring tape, where the collected data were the amount and spacing of seedlings in 2 meters in three random lines. The area used in this experiment had three blocks with 17 plots. Data were collected for plant stand, normal, faulty, and double spacing and normalized difference vegetation index (NDVI), subjected to descriptive and variance statistical analysis. The average data of plants per meter can be considered low for soybean culture since the regional average has been 10 to 14 plants per meter in highly fertile soils. Another factor that presented very low average values was the normal spacing, around 36%, as an adequate distribution for the pneumatic seeder should be 90%. There was no observed effect of rotations on the emergence and establishment process of the culture, indicating that the low regularity of distribution may be associated with the seeder used. The use of NDVI allows identifying rotations with lower soybean vegetative development, and the fallow, safflower rotation, and the Nabo + oats + niger + buckwheat consortium had the lowest values throughout the culture's development.