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Monitoring Nitrate Leaching from Submerged Drains
Author(s) -
Vos J.A.
Publication year - 2001
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2001.3031092x
Subject(s) - leaching (pedology) , ditch , drainage , environmental science , loam , soil water , hydrology (agriculture) , lessivage , tile drainage , nitrate , water quality , groundwater , surface water , well drainage , water flow , soil science , environmental engineering , chemistry , geology , geotechnical engineering , soil salinity , ecology , organic chemistry , biology
Monitoring nitrate N (NO 3 –N) leaching is important in order to judge the effect that agricultural practices have on the quality of ground water and surface water. Measuring drain discharge rates and NO 3 –N concentrations circumvents the problem of spatial variability encountered by other methods used to quantify NO 3 –N leaching in the field. A new flow‐proportional drainage water sampling method for submerged drains has been developed to monitor NO 3 –N leaching. Both low and high discharge rates can be measured accurately, and are automatically compensated for fluctuations in ditch‐water levels. The total amount of NO 3 –N leached was 10.6 kg N ha −1 for a tile‐drained silt‐loam soil during the 114‐d monitoring period. The NO 3 –N concentrations fluctuated between 5 mg L −1 at deep ground water levels and 15 mg L −1 at shallow levels, due to variations in water flow. A flow‐proportional drainage water sampling method is required to measure NO 3 –N leaching accurately under these conditions. Errors of up to 43% may occur when NO 3 –N concentrations in the drainage water are only measured at intervals of 30 d and when the precipitation excess is used to estimate cumulative NO 3 –N leaching. Measurements of NO 3 –N concentrations in ground water cannot be used to accurately estimate NO 3 –N leaching in drained soils.