Impacts of converting low-intensity pastureland to high-intensity bioenergy cropland on the water quality of tropical streams in Brazil

Author(s)

Taniwaki, Ricardo Hideo ; Cassiano, Carla Cristina ; Filoso, Solange ; de Barros Ferraz, Silvio Frosini ; de Camargo, Plinio Barbosa ; Martinelli, Luiz Antonio

• Document type: Journal article
• Source: Science of The Total Environment; v. 584, p. 339-347, APR 15 2017.
• Web of Science Citations: 17

Abstract

In Brazil, the cultivation of bioenergy crops is expanding at an accelerated rate. Most of this expansion has occurred over low-intensity pasture and is considered sustainable because it does not involve deforestation of natural vegetation. However, the impacts on the water quality of headwater streams are poorly understood, especially with regard to the influence of land use patterns in the watershed. In this study, we investigated the effects of land-use conversion on the water quality of streams draining sugarcane fields and examined whether the preservation of forested areas at the top of the headwaters would help mitigate the negative impacts of intensive agriculture. Water samples were collected in two paired catchments in southeastern Brazil, which is one of the largest sugarcane production regions in the world. Our results show significant differences in the water quality of streams predominantly draining the pasture or the sugarcane field. SeVeral parameters commonly used to indicate water quality, such as the concentrations of nitrate and suspended solids, were significantly higher in the sugarcane than in the pasture stream. Differences in water quality between the streams draining predominantly pasture or sugarcane fields were accentuated during the wet season. The preservation of forests surrounding the headwater streams was associated with overall better water quality conditions, such as lower nitrate concentrations and temperature of the stream water. We concluded that forest conservation in the headwater agricultural catchments is an important factor preventing water quality degradation in tropical streams. Therefore, we strongly recommend the preservation of robust riparian forests in the headwaters of tropical watersheds with intensive agriculture. More studies on the effects of best agricultural practices in bioenergy crops can greatly improve our capacity to prevent the degradation of water quality in the tropical waterways as intensive agriculture continues to expand in this region of the world. (C) 2016 Elsevier B.V. All rights reserved. (AU)

• FAPESP's process: 13/22679-5 - Eco-hidrological functions of riparian forests in intensity gradients of agricultural landscape management
• Grantee: Silvio Frosini de Barros Ferraz
• Support Opportunities: Regular Research Grants
• FAPESP's process: 11/19767-4 - The role of forest fragments in controlling water quality and ecosystem functioning of streams draining agricultural catchments
• Grantee: Silvio Frosini de Barros Ferraz
• Support Opportunities: Regular Research Grants
• FAPESP's process: 12/03527-7 - Ecosystemic functions of riparian vegetation in agricultural landscapes on the primary productivity of streams
• Grantee: Ricardo Hideo Taniwaki
• Support Opportunities: Scholarships in Brazil - Doctorate