Sediments produced from eroding cultivated land can cause on-site and off-site effects that cause considerable economic and social impacts. Despite the importance of soil conservation practices (SCP) for the control of soil erosion and improvements in soil hydrological functions, limited information is available regarding the effects of SCP on sediment yield (SY) at the catchment scale. This study aimed to investigate the long-term relationships between SY and land use, soil management, and rainfall in a small catchment. To determine the effects of anthropogenic and climatic factors on SY, rainfall, streamflow, and suspended sediment concentration were monitored at 10-min intervals for 14 years (2002–2016), and the land use and soil management changes were surveyed annually. Using a statistical procedure to separate the SY effects of climate, land use, and soil management, we observed pronounced temporal effects of land use and soil management changes on SY. During the first 2 years (2002–2004), the land was predominantly cultivated with tobacco under a traditional tillage system (no cover crops and ploughed soil) using animal traction. In that period, the SY reached approximately 400 t·km−2·year−1. From 2005 to 2009, a soil conservation programme introduced conservation tillage and winter cover crops in the catchment area, which lowered the SY to 50 t·km−2·year−1. In the final period (2010–2016), the SCP were partially abandoned by farmers, and reforested areas increased, resulting in an SY of 150 t·km−2·year−1. This study also discusses the factors associated with the failure to continue using SCP, including structural support and farmer attitudes.
Bibliographical noteFunding Information:
Sinditabaco (The Interstate Tobacco Industry Union); FINEP (Funding for Studies and Projects); CNPq (The National Council for Scientific and Technological Development); FAPERGS (The Foundation for Research of Rio Grande do Sul)
The authors would like to thank Adair and Ademir Giongo for their valuable help with field work, Augusto Araújo and Elena Metcalf for their valuable contributions towards improving this manuscript, and the financial support of FAPERGS (The Foundation for Research of Rio Grande do Sul), CNPq (The National Council for Scientific and Technological Development), FINEP (Funding for Studies and Projects), and Sinditabaco (The Interstate Tobacco Industry Union).
- catchment monitoring
- climate effects
- environmental impact
- soil erosion