Nitrogen and Carbon Leaching in Agroecosystems and Their Role in Denitrification Potential

• Published in: Journal of environmental quality Vol. 30; no. 1; pp. 58 - 70
• Main Authors: Brye, K.R., Norman, J.M., Bundy, L.G., Gower, S.T.
• Format: Journal Article
• Language: English
• Published: Madison American Society of Agronomy, Crop Science Society of America, Soil Science Society 01-01-2001; Crop Science Society of America; American Society of Agronomy
• Subjects: Agricultural ecosystems; Agriculture; Agronomy. Soil science and plant productions; Biological and medical sciences; Carbon; Carbon - chemistry; Denitrification; Dissolved organic carbon; Drainage; Ecosystem; Environmental Monitoring; Fundamental and applied biological sciences. Psychology; Leaching; Lysimeters; Nitrates; Nitrates - analysis; Nitrates - metabolism; Nitrogen; Nitrogen - chemistry; Nitrogen Fixation; Root zone; Saturated soils; Silt loam; Soil and water pollution; Soil Pollutants - analysis; Soil Pollutants - metabolism; Soil science; Subsoils; Tillage; United States; North America; Wisconsin; America; Nitrogen fertilization; Monocotyledones; Underground leaching; Soil tillage; Zea mays; Cultivated soil; Lysimetry; Nitrates; Zero tillage; Mollisols; Cereal crop; Agroecosystem; Dissolved organic carbon; Nitrogen cycle; Silt loam soil; Gramineae; Angiospermae; Water quality; Denitrification; Water pollution; Spermatophyta; Drainage water; Grassland soil
• ISSN: 0047-2425; 1537-2537
• DOI: 10.2134/jeq2001.30158x

The drainage of water and leaching of dissolved constituents represent major components of agroecosystem mass budgets that have been exceedingly difficult to measure. Equilibrium‐tension lysimeters (ETLs) were used to monitor drainage, nitrogen (N), and carbon (C) leaching through Plano silt loam (fine‐silty, mixed, superactive, mesic Typic Argiudoll) for a 4‐yr period in a restored prairie and N‐fertilized no‐tillage and chisel‐plowed maize (Zea mays L.) agroecosystems. Mean drainage recorded during 4 yr for the prairie, no‐tillage, and chisel‐plowed ecosystems totaled 461, 1116, and 1575 mm and represented 16, 33, and 47% of precipitation plus melting of drifted snow received, respectively. Total inorganic N leaching losses during the 4‐yr period for the prairie, no‐tillage, and chisel‐plowed ecosystems were 0.6, 201, and 179 kg N ha−1, respectively. Inorganic N leaching represented 26 and 24% of applied fertilizer N additions to the no‐tillage and chisel‐plowed agroecosystems. Total dissolved C leaching losses were 119, 435, and 502 kg C ha−1 for the prairie, no‐tillage, and chisel‐plowed ecosystems, respectively. Sufficient dissolved organic carbon (DOC) and nitrate N (NO−3–N) existed in the prairie and agroecosystems to support subsoil denitrification. Potential denitrification, however, was limited by insufficient lengths of saturated soil conditions in all three ecosystems, the supply of DOC in the agroecosystems, and the supply of nitrate N in the prairie. Based on available DOC and nitrate N, the maximum contribution of denitrification below the root zone in the agroecosystems was less than 25% of the total amount of leached nitrate N and the probable contribution of denitrification was much less.