Variabilidade espacial da resistência do solo a penetração mecânica em áreas de várzea cultivadas com soja

Abstract

With the increased participation of soybean cultivation in rotating in floodplains areas with irrigated rice, it is necessary to seek alternatives to increase the productivity of this crop in these areas and to minimize environmental impacts. One of the factors that make it difficult to use of floodplain areas for the implantation of non-irrigated crops is the compaction of the soil, which limits the root development of the plants, besides stress caused by hypoxia in the root zones when under soil flooding conditions. One of the methods used to determine the occurrence of compacted zones is soil penetration resistance. Within this context, it is necessary to use Precision Agriculture techniques that can contribute to solve the problems. The objective of this work was to identify the variability and the interference level of the soil resistance to mechanical penetration in the yield of soybeans implanted in rotation with irrigated rice through the use of geostatistical techniques. The work was carried out in an floodplain area, in the municipality of Itaqui / RS, where the soybean crop was implanted in succession to the irrigated rice. For this, soil penetration determinations were performed at four depths (0-10 cm; 11-20 cm; 21-30 cm e 31-40 cm), of soil moisture at two depths (0-20 cm e 21-40 cm) and productivity in an area of 1,13 ha-1, using a sample grid of 10 x 10 meters, totaling 113 sample points. The penetration resistance increased in depth, regardless of the increase of humidity, presenting values restrictive to root growth between 5 and 35 cm depth. Soil penetration resistance showed significant negative correlation with moisture at depths of 0-10 cm, 11-20 cm and 21-30 cm. It was not possible to obtain a correlation between the productivity and the other attributes studied. It was verified that the resistance to penetration in the 0-10 cm layer did not show spatial dependence. The other attributes presented moderate or strong spatial dependence, thus validating the use of the grid used.