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The balance between precipitation and evapotranspiration (ET) has direct effect on vegetation, and any change in its structure and composition can influence it. The aim of this study is to determine experimentally the daily evapotranspiration (ET) of the invasive species, Hedychium coronarium, and to compare with a group of four native species of the riparian forest. The experiment was carried out in a greenhouse with three different treatments: (1) only the invasive species; (2) only native species; and (3) a mixture of invasive and native species. In each lysimeter, pressure transducers recorded the water level at every 15 min along 14 months. Daily ET was calculated by the method of Gribovszki et al. (2008) and varied according to the treatment, indicating that different species (invasive or native) use the water differently. The maximum accumulated daily ET occurred for mixture treatment (2540.16 mm), while the treatment with the invasive plant presented the lowest value (2172.53 mm). H. coronarium, in monodominant stands, can reduce evapotranspiration on invaded areas and increase it when immersed in the riparian forest. [ABSTRACT FROM AUTHOR]

Automated soil moisture systems are commonly used in precision agriculture. Using low-cost sensors, the spatial extension can be maximized, but the accuracy might be reduced. In this paper, we address the trade-off between cost and accuracy comparing low-cost and commercial soil moisture sensors. The analysis is based on the capacitive sensor SKU:SEN0193 tested under lab and field conditions. In addition to individual calibration, two simplified calibration techniques are proposed: universal calibration, based on all 63 sensors, and a single-point calibration using the sensor response in dry soil. During the second stage of testing, the sensors were coupled to a low-cost monitoring station and installed in the field. The sensors were capable of measuring daily and seasonal oscillations in soil moisture resulting from solar radiation and precipitation. The low-cost sensor performance was compared to commercial sensors based on five variables: (1) cost, (2) accuracy, (3) qualified labor demand, (4) sample volume, and (5) life expectancy. Commercial sensors provide single-point information with high reliability but at a high acquisition cost, while low-cost sensors can be acquired in larger numbers at a lower cost, allowing for more detailed spatial and temporal observations, but with medium accuracy. The use of SKU sensors is then indicated for short-term and limited-budget projects in which high accuracy of the collected data is not required. [ABSTRACT FROM AUTHOR]

The planting of sugarcane crops has expanded in the last decade in the southeast of Brazil, mainly due to its use for biofuel production, such as ethanol. This expansion in the State of São Paulo has occupied land that was previously used for cattle production. The change in land use affects soil and water through changes in ground cover and disturbance associated with farming practices. The objective of the following study was to determine the impact on runoff and erosion resulting from the conversion of pastureland to sugarcane for biofuel production. Erosion plots measuring 100 m2 were built on a farm in Itirapina-SP, Brazil, on land with a slope gradient of 9% and soil composed of Quartz-sand Neosols (Typic quartzipsaments). The treatments were an 18-year old pasture and a new sugarcane plantation, with three replicates for each. After each rainfall episode, erosion and runoff were monitored during the first and second years after sugarcane was planted. The results show increased runoff and soil loss during the first year, though levels decreased in the second year when the sugarcane residue mulch ground cover increased. In addition, the necessary rainfall characteristics (e.g., intensity, duration) required to produce runoff and soil erosion were identified. [ABSTRACT FROM AUTHOR]

An important unsolved question in hydrology science is the consequence of the Eucalyptus afforestation on groundwater recharge. Here, we assessed recharge estimates before and after converting pasture cover to Eucalyptus plantation. Groundwater levels, recharge, rainfall (P) and actual evapotranspiration (ET) were evaluated from 2004 through 2016 over an outcrop area of the Guarani Aquifer System (GAS) in the southeastern Brazil. Recharge was estimated using the water-table fluctuation method. We observed a decrease of 100 mm/year in groundwater levels after land use changed from pasture to Eucalyptus. The average recharge decreased from 407 mm/year (27% of mean P) to 194 mm/year (13% of mean P) after land use change over the study area. We found a recharge decrease of 19% in 2012 and 58% in 2013 under similar annual rainfall in comparison with the long-term mean recharge (from 2004 to 2016). Our results indicated that the high values of ET observed in Eucalyptus plantation decreases water availability for recharge. Therefore, our findings are important to agencies for decision-making in water resources regarding the management of land cover and land use. [ABSTRACT FROM AUTHOR]