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| Titel |
Assessment of Nitrate-N Load in Subsurface Drainage Water from the Agricultural Fields in the Fergana Valley, Uzbekistan |
| VerfasserIn |
S. Kenjabaev, I. Forkutsa, V. Dukhovny, H. G. Frede |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250067953
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| Zusammenfassung |
| Leaching of nitrate-N (NO3-) from irrigated agricultural land and water contamination have
become a worldwide concern. This study was conducted to investigate amount of nitrate-N
leached to groundwater and surface water from irrigated cotton, winter wheat and maize
fields in the Fergana Valley (Uzbekistan). Therefore at two sites (“Akbarabad” and
“Azizbek”) equipped with closed horizontal drainage system during 2010-2011 vegetation
seasons we monitored water flow, nutrient concentrations and salinity at surface and
subsurface drains, at irrigation canals and groundwater. We also applied stable isotopes (δ2H
and δ18O) method in order to investigate the source of drainage water runoff. Discussed are
results of 2010.
Farmers fertilized cotton fields with ammonium nitrate of 350-450 kg ha-1 in
“Akbarabad” and 700 kg ha-1 in “Azizbek” sites. In winter wheat and maize fields (in
“Akbarabad”) about 500 kg ha-1 of ammonium nitrate were applied. Cotton fields were
irrigated with 2700 m3Â ha-1 (“Akbarabad”) and 3500 m3Â ha-1 (“Azizbek”). In winter wheat
and maize fields applied irrigation water amounted to 3900 m3Â ha-1 and 723 m3Â ha-1,
respectively.
Frequent groundwater and subsurface drainage water sampling revealed that nitrate
leaching occurred mostly during and right after the irrigation events. The estimated average
nitrate-N concentration in subsurface drainage water in “Akbarabad” was slightly higher (9
mg l-1) than in “Azizbek” (8 mg l-1). During July-November (2010), in average, nitrate-N
losses through subsurface drainage amounted to 24 kg ha-1 in “Akbarabad” and 18 kg ha-1
in “Azizbek”. The salinity of drainage water at both sites was similar and varied between
2.3-2.7 dSÂ m-1.
Preliminary results of isotope signals of studied water (precipitation, drainage, irrigation
and ground water) indicate that the source of drainage water runoff comes from the irrigation
water, while the contribution of rainfall is negligible. It is planned to run simulations with
DRAINMOD model for further investigation of water and N balances of the selected sites.
Developed recommendations for farmers on optimum irrigation water amounts and N
fertilization will allow reducing environmental risks in agricultural lands of the Fergana
Valley. |
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