Watershed responses to Amazon soya bean cropland expansion and intensification Journal Article

Authors: Neill, C.; Coe, M. T.; Riskin, S. H.; Krusche, A. V.; Elsenbeer, H.; Macedo, M. N.; McHorney, R.; Lefebvre, P.; Davidson, E. A.; Scheffler, R.; Figueira, A. M.; Porder, S.; Deegan, L. A.
Article Title: Watershed responses to Amazon soya bean cropland expansion and intensification
Abstract: The expansion and intensification of soya bean agriculture in southeastern Amazonia can alter watershed hydrology and biogeochemistry by changing the land cover, water balance and nutrient inputs. Several new insights on the responses of watershed hydrology and biogeochemistry to deforestation in Mato Grosso have emerged from recent intensive field campaigns in this region. Because of reduced evapotranspiration, total water export increases threefold to fourfold in soya bean watersheds compared with forest. However, the deep and highly permeable soils on the broad plateaus on which much of the soya bean cultivation has expanded buffer small soya bean watersheds against increased stormflows. Concentrations of nitrate and phosphate do not differ between forest or soya bean watersheds because fixation of phosphorus fertilizer by iron and aluminium oxides and anion exchange of nitrate in deep soils restrict nutrient movement. Despite resistance to biogeochemical change, streams in soya bean watersheds have higher temperatures caused by impoundments and reduction of bordering riparian forest. In larger rivers, increased water flow, current velocities and sediment flux following deforestation can reshape stream morphology, suggesting that cumulative impacts of deforestation in small watersheds will occur at larger scales.
Keywords: TEMPERATURE; HYDROLOGY; ECOSYSTEM; Brazil; water quality; Soil/chemistry; Conservation of Natural Resources/methods; Agriculture/methods; Crops, Agricultural/growth development; Nitrates/chemistry; Phosphorus/chemistry; Rivers/chemistry; Soybeans/growth development
Journal Title: Philosophical Transactions of the Royal Society of London Series B-Biological Sciences
Volume: 368
Issue: 1619
ISSN: 0962-8436
Publisher: Royal Society, The  
Publication Place: England
Date Published: 2013
Start Page: 20120425
Language: eng
Notes: JID: 7503623; 0 (Nitrates); 0 (Soil); 27YLU75U4W (Phosphorus); OID: NLM: PMC3638438 [Available on 06/05/14]; PMCR: 2014/06/05 00:00; 2013 [ppublish]; epublish