Conservationist strategies to minimize erosion potential due to rainfall anomalies on cultivated lands in Belterra, Pará
DOI:
https://doi.org/10.6008/CBPC2179-6858.2019.001.0017Keywords:
Erosion, Rainfall, Soil Cover, Anthropic UseAbstract
The objective of this work was to estimate erosive potential and rainfall anomalies in Belterra, an important municipality that integrates centers of grain production in the western portion of the State of Pará. Rainfall data were obtained from the BDMEP database of the National Institute of Meteorology (INMET) from 1972 to 2017. Rainfall erosivity was estimated using monthly and annual rainfall totals to calculate the erosivity coefficient (Rc), where monthly rainfall is squared and divided by the total rainfall in Belterra. In addition, years with rainfall anomalies (IAC) were tracked to identify extreme conditions (excess and deficit volumes) and to analyze low to high erosivity levels. The results show that the rainiest year was 1985 with a total of 3.057,0 mm, and the lowest rainfall occurred in 1992 (974.2 mm). During the analyzed period annual average erosivity was estimated at 13,000 MJ mm ha-1 h-1 year-1, indicating a high potential for erosion in Belterra. During the months with greatest rainfall (January to May) there is an elevated potential for erosion that is intensified (positive anomaly) under La Niña conditions. In Belterra There is a predominance of climatic mechanisms typical of El Niño, and negative anomalies are common under this condition due to rainfall reduction in the region, and the strongest year for this was 1992. The erosivity index for Belterra is highest during the period of intensification of soil management (January to May) for grain planting and harvest. During anomalous climatic years such as when a strong La Niña occurs bringing heavy rainfall there is greater potential for erosion caused by superficial water flow, principally in areas with no soil vegetation cover. The increase in area dedicated to grain cultivation that occurred between 2014-16 is cause for preoccupation with respect to impacts from erosion, and conservationist practices are recommended such as no-till planting using mulch, and this is supported by soil quality indicators from studies in other regions in Brazil.
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