Análise do armazenamento de água no solo cultivado com soja, sob três sistemas de manejo, em Vilhena-RO

Abstract

This study aimed to understand the relationship of the use of different management techniques with the impact on water storage in the soil, and its influence on the development and productivity of soybean crop. For this, a field experiment was conducted at the experimental site of the Faculdade Marechal Rondon (FARON) in Vilhena- RO, during the soybean crop 2020/2021. In a randomized block design, in subdivided plots, the soybean cultivar 83HO113 IPRO was sown on two different dates (10/15/2021 and 11/12/2021), under different soil density and cover conditions: traditional planting conditions of the region (no-till) and soil with minimum tillage (with previous plowing for 90 days (0-30 cm) ); and with three cover characteristics: exposed, with corn stover cover and intercropped with Brachiaria brizanta cv. Marandu. During the harvest, agrometeorological data were collected on precipitation, air temperature and relative humidity, incident solar radiation, wind speed and direction, surface runoff, photosynthetically active radiation, and soil moisture, as well as physical and chemical soil data. By means of the integration methods of volumetric soil moisture and the water balance technique, the soil water storage for the first sowing date was obtained, which resulted in average errors of less than -0.33 mm/day, so the water balance method can be used to estimate the soil water stock. By the Tukey method, no statistical differences were observed between the soil managements, mainly because of the uniformity of rainfall distribution during the experiment, so it is expected that under water stress conditions these differences will be statistically significant. However, the soil conditions were significantly different, highlighting the importance of no-till farming for the region. The effects of the different sowing dates were statistically different, associated with the absence of precipitation at the beginning of the reproductive stage on the second sowing date. This work contributed to new information for soybean management in the Vilhena-RO region, and shows the importance of soil cover and soil physical conditions in regulating surface water storage in soybean cultivation.