TY - JOUR
T1 - Nitrogen cycling and tile drainage nitrate loss in a corn/soybean watershed
AU - Gentry, Lowell E.
AU - David, Mark B.
AU - Smith, Karen M.
AU - Kovacic, David A.
N1 - Funding Information:
This study was supported in part by the Illinois Groundwater Consortium, USDA Competitive Grants Program, and the Illinois C-FAR program. The authors thank Dr. J.E. Harper for review comments.
PY - 1998/3
Y1 - 1998/3
N2 - Nitrogen (N) in surface waters has been linked to agricultural crop production, and more specifically, tO NO3/- exported by tile drainage. The objective of this study was to evaluate agricultural N pools and fluxes in a seed corn/soybean (Zea maize L./Glycine max L.) watershed (40 ha) to relate soil inorganic N pools with annual losses of NO3/- in drainage tiles. During a 2-year period beginning in October 1993, soil samples in the top 50 cm located near the tile systems (predominantly Drummer silty clay loam, fine-silty, mixed mesic Typic Haplaquolls) were analyzed for microbial biomass C and N, inorganic N, and N mineralization rates. Water flow and NO3/- concentrations were continuously measured in the three drainage tiles. Soil microbial biomass N ranged from 83 to 156 kg N ha-1, and appeared more closely related to soil moisture than soil inorganic N pools. Soil inorganic N ranged from a low of 13 kg N ha-1 during the soybean growing season to a high of 115 kg N ha-1 after N fertilization. Following good growing seasons in 1993 and 1994, high crop uptake of N resulted in relatively small soil inorganic N pools of 40 and 24 kg N ha-1, respectively, after crop harvest. In 1995, however, when poor growing conditions decreased crop N accumulation, 98 kg N ha-1 remained in the watershed after harvest. Based on an average effective drainage area of 30 ha, 38 and 64 kg N ha-1 leached out of the Watershed through file drainage for a total of 3.1 Mg N for the 1995 and 1996 water years, respectively. Tile N export from the watershed was greatest during high flow events when there concurrently existed large pools of soil inorganic N in the form of NO3-. Differences in annual N export for each tile were the result of a combination of factors including; timing and area of N fertilization, amount and distribution of precipitation, crop uptake of soil derived N, and inorganic N pools remaining after harvest.
AB - Nitrogen (N) in surface waters has been linked to agricultural crop production, and more specifically, tO NO3/- exported by tile drainage. The objective of this study was to evaluate agricultural N pools and fluxes in a seed corn/soybean (Zea maize L./Glycine max L.) watershed (40 ha) to relate soil inorganic N pools with annual losses of NO3/- in drainage tiles. During a 2-year period beginning in October 1993, soil samples in the top 50 cm located near the tile systems (predominantly Drummer silty clay loam, fine-silty, mixed mesic Typic Haplaquolls) were analyzed for microbial biomass C and N, inorganic N, and N mineralization rates. Water flow and NO3/- concentrations were continuously measured in the three drainage tiles. Soil microbial biomass N ranged from 83 to 156 kg N ha-1, and appeared more closely related to soil moisture than soil inorganic N pools. Soil inorganic N ranged from a low of 13 kg N ha-1 during the soybean growing season to a high of 115 kg N ha-1 after N fertilization. Following good growing seasons in 1993 and 1994, high crop uptake of N resulted in relatively small soil inorganic N pools of 40 and 24 kg N ha-1, respectively, after crop harvest. In 1995, however, when poor growing conditions decreased crop N accumulation, 98 kg N ha-1 remained in the watershed after harvest. Based on an average effective drainage area of 30 ha, 38 and 64 kg N ha-1 leached out of the Watershed through file drainage for a total of 3.1 Mg N for the 1995 and 1996 water years, respectively. Tile N export from the watershed was greatest during high flow events when there concurrently existed large pools of soil inorganic N in the form of NO3-. Differences in annual N export for each tile were the result of a combination of factors including; timing and area of N fertilization, amount and distribution of precipitation, crop uptake of soil derived N, and inorganic N pools remaining after harvest.
KW - Crop uptake
KW - Inorganic N
KW - Maize
KW - Microbial biomass N
KW - N mineralization
KW - Soybean
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U2 - 10.1016/S0167-8809(97)00139-4
DO - 10.1016/S0167-8809(97)00139-4
M3 - Article
AN - SCOPUS:0031967437
SN - 0167-8809
VL - 68
SP - 85
EP - 97
JO - Agriculture, Ecosystems and Environment
JF - Agriculture, Ecosystems and Environment
IS - 1-2
ER -