More is less: agricultural impacts on the N cycle in Argentina

Austin, Amy T.; Piñeiro, Gervasio; González-Polo, Marina

doi:10.1007/978-1-4020-5517-1_3

Cited by 4 publications

(3 citation statements)

References 37 publications

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“…Agriculturally dominated areas are usually regarded as a source non-point N pollution, caused by greater N inputs in the form of chemical fertilizers and manure (Austin et al 2006;Chen et al 2008), Various studies have shown that river N concentrations and loads are strongly correlated with watershed N input Duan et al 2007;Sobota et al 2009). In the WCW, a purely agricultural catchment, and the JRW, with a less than 20% urban population, agricultural activities have become the dominant anthropogenic contribution to N export via surface runoff and its eventual delivery to coastal region.…”

Section: Discussionmentioning

confidence: 99%

Nitrogen export by surface runoff from a small agricultural watershed in southeast China: seasonal pattern and primary mechanism

Chen

Hong

2010

Biogeochemistry

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The seasonal pattern and primary mechanism of nitrogen (N) export by surface runoff from the Wuchuan subwatershed (WCW), an agricultural upper watershed (1.88 km 2 ) located in southeast China, were investigated based on extensive streamwater measurements in 2004-2005 under subtropical climatic conditions. The results disclosed a highly variable but strong linkage between hydrological and anthropogenic controls and N export. N export via surface runoff presented a significant seasonal pattern caused by changes in rainfall and watershed N input. Approximately 75% of the annual N export (67 kg ha -1 ) was flushed by those storm runoff mainly occurred during the wet season (March through September). The WCW dataset of N concentrations and loads during both baseflow and stormflow implied an interactive effects of anthropogenetic N input and hydrology conditions: N export was flush-driven in late spring, summer and autumn (wet season), but highly related with soil N in winter and early spring. Compared to undisturbed watersheds under similar rainfall conditions, WCW exported a considerable amount of N due to intensive fertilizer application (a mean of 690 kg N ha -1 year -1 , commonly as surface applications). This work provides a first characterization of a small agricultural Chinese catchment under subtropical climates and its associated N export behavior.

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Section: Discussionmentioning

confidence: 99%

Nitrogen export by surface runoff from a small agricultural watershed in southeast China: seasonal pattern and primary mechanism

Chen

Hong

2010

Biogeochemistry

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“…Although the national use of fertilizers experienced a 4-fold increase between 1990 and 2000 (SAGPyA 2002), application rates are still low and mainly related to corn and wheat production, which amounts to 23% of the cultivated area (SAGPyA 2005). In addition, the most widespread crop of the region, soybean, is rarely fertilized with N and seems to have negative N balances (Á lvarez et al 1995;Austin et al 2006). Nitrogen exports from soils to streams and groundwater under the new scheme of intensive cropping of the Pampas has received little attention.…”

Section: Introductionmentioning

confidence: 98%

Fertilizer vs. organic matter contributions to nitrogen leaching in cropping systems of the Pampas: 15N application in field lysimeters

et al. 2006

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Nitrogen (N) export from soils to streams and groundwater under the intensifying cropping schemes of the Pampas is modest compared to intensively cultivated basins of Europe and North America; however, a slow N enrichment of water resources has been suggested. We (1) analyzed the fate of fertilizer N and (2) evaluated the contribution of fertilizer and soil organic matter (SOM) to N leaching under the typical cropping conditions of the Pampas. Fertilizer N was applied as 15 N-labeled ammonium sulfate to corn (in a corn/soybean rotation) sown under zero tillage in filled-in lysimeters containing two soils of different texture representative of the Pampean region (52 and 78 kg N ha -1 , added to the silt loam and sandy loam soil, respectively). Total fertilizer recovery at corn harvest averaged 84 and 64% for the silt loam and sandy loam lysimeters, respectively. Most fertilizer N was removed with plant biomass (39%) or remained immobilized in the soil (29 and 15%, for the silt loam and sandy loam soil, respectively) whereas its loss through drainage was negligible (<0.01%). We presume that the unaccounted fertilizer N losses were related to volatilization and denitrification. Throughout the corn growing season, subsequent fallow and soybean crop, which took place during an exceptionally dry period, the fertilizer N immobilized in the organic pool remained stable, and N leaching was scarce (7.5 kg N ha -1 ), similar at both soils, and had a low contribution of fertilizer N (0-3.5%), implying that >96% of the leached N was derived from SOM mineralization. The inherent high SOM of Pampean soils and the favorable climatic conditions are likely to propitiate year-round production of nitrate, favoring its participation in crop nutrition and leaching. The presence of 15 N in drainage water, however, suggests that fertilizer N leaching could become significant in situations with higher fertilization rates or more rainy seasons.

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“…The massive amount of glyphosate herbicides used on GM soy has lead to increasing glyphosate resistance in native weed species (Vila-Aiub et al 2007), although the herbicide is considered less toxic than many of the compounds that it replaces (Trigo and Cap 2003). Other scholars have raised concerns over soil phosphorus and nitrogen losses from intensive soy cultivation in the Pampas (Austin et al 2006). A study now underway in the University of Rio Cuarto suggests that the cessation of crop rotations and fallowing affect the price of land rentals, which decline substantially as a function of the number of years the land has been cultivated intensively in soybean.…”

Section: The Vulnerability-sustainability Linkmentioning

confidence: 97%

Linking local vulnerability to system sustainability in a resilience framework: two cases from Latin America

2008

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Collectively, individual adjustments to environmental and economic change can have disproportionate influence on the sustainability of the broader social-environmental system in which exposure takes place. Here we focus on the specific mechanisms by which farm-level responses to globalization and environmental change feedback to affect the sustainability and resilience of the socialenvironment system. We use a proposal by Lambin as an analytical frame for understanding this feedback, illustrating how information, motivation and capacity collectively structure the ways in which the actions of individuals can transform regional economies and landscapes. We draw on two Latin American case studies to illustrate the collective and synergistic implications of farmers' livelihood and land use choices for the sensitivity of the region to future market and environmental shocks, as well as for the role of the landscapes in the global carbon cycle. We argue that the potential disconnect between individual goals of livelihood security and broader aims of system sustainability can be bridged through improved governance and attention to the role of policy, individual and collective experience, and resource constraints in adaptive choice.

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More is less: agricultural impacts on the N cycle in Argentina

Cited by 4 publications

References 37 publications

Nitrogen export by surface runoff from a small agricultural watershed in southeast China: seasonal pattern and primary mechanism

Nitrogen export by surface runoff from a small agricultural watershed in southeast China: seasonal pattern and primary mechanism

Fertilizer vs. organic matter contributions to nitrogen leaching in cropping systems of the Pampas: 15N application in field lysimeters

Linking local vulnerability to system sustainability in a resilience framework: two cases from Latin America

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