TY  - JOUR
A1  - Neill, Christopher
A1  - Jankowski, KathiJo
A1  - Brando, Paulo M.
A1  - Coe, Michael T.
A1  - Deegan, Linda A.
A1  - Macedo, Marcia N.
A1  - Riskin, Shelby H.
A1  - Porder, Stephen
A1  - Elsenbeer, Helmut
A1  - Krusche, Alex V.
T1  - Surprisingly Modest Water Quality Impacts From Expansion and Intensification of Large-Sscale Commercial Agriculture in the Brazilian Amazon-Cerrado Region
JF  - Tropical conservation science
N2  - Large-scale commercial cropping of soybeans expanded in the tropical Amazon and Cerrado biomes of Brazil after 1990. More recently, cropping intensified from single-cropping of soybeans to double-cropping of soybeans with corn or cotton. Cropland expansion and intensification, and the accompanying use of mineral fertilizers, raise concerns about whether nutrient runoff and impacts to surface waters will be similar to those experienced in commercial cropland regions at temperate latitudes. We quantified water infiltration through soils, water yield, and streamwater chemistry in watersheds draining native tropical forest and single-and double-cropped areas on the level, deep, highly weathered soils where cropland expansion and intensification typically occurs. Although water yield increased four-fold from croplands, streamwater chemistry remained largely unchanged. Soil characteristics exerted important control over the movement of nitrogen (N) and phosphorus (P) into streams. High soil infiltration rates prevented surface erosion and movement of particulate P, while P fixation in surface soils restricted P movement to deeper soil layers. Nitrogen retention in deep soils, likely by anion exchange, also appeared to limit N leaching and export in streamwater from both single-and double-cropped watersheds that received nitrogen fertilizer. These mechanisms led to lower streamwater P and N concentrations and lower watershed N and P export than would be expected, based on studies from temperate croplands with similar cropping and fertilizer application practices.
KW  - water
KW  - quality
KW  - agriculture
KW  - intensification
KW  - impact
Y1  - 2017
U6  - https://doi.org/10.1177/1940082917720669
SN  - 1940-0829
VL  - 10
PB  - Sage Publ.
CY  - Thousand Oaks
ER  - 
TY  - JOUR
A1  - Neill, Christopher
A1  - Coe, Michael T.
A1  - Riskin, Shelby H.
A1  - Krusche, Alex V.
A1  - Elsenbeer, Helmut
A1  - Macedo, Marcia N.
A1  - McHorney, Richard
A1  - Lefebvre, Paul
A1  - Davidson, Eric A.
A1  - Scheffler, Raphael
A1  - Figueira, Adelaine Michela e Silva
A1  - Porder, Stephen
A1  - Deegan, Linda A.
T1  - Watershed responses to Amazon soya bean cropland expansion and intensification
JF  - Philosophical transactions of the Royal Society of London : B, Biological sciences
N2  - 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.
KW  - soya beans
KW  - watersheds
KW  - nitrogen
KW  - phosphorus
KW  - soil
Y1  - 2013
U6  - https://doi.org/10.1098/rstb.2012.0425
SN  - 0962-8436
SN  - 1471-2970
VL  - 368
IS  - 1619
PB  - Royal Society
CY  - London
ER  -