Estimating Soil Mineralizable Nitrogen under Different Management Practices

• Published in: Soil Science Society of America journal Vol. 70; no. 5; pp. 1522 - 1531
• Main Authors: Mikha, M.M, Rice, C.W, Benjamin, J.G
• Format: Journal Article
• Language: English
• Published: Madison Soil Science Society 01.09.2006; Soil Science Society of America; American Society of Agronomy
• Subjects: Agricultural management; Agronomy. Soil science and plant productions; animal manures; Biological and medical sciences; continuous cropping; conventional tillage; corn; Crop residues; Earth sciences; Earth, ocean, space; Environmental impact; Environmental management; equations; estimation; Exact sciences and technology; fertilizer application; Fundamental and applied biological sciences. Psychology; Mineralization; mineralization rate constant; Minerals; Moisture content; Nitrogen; nitrogen fertilizers; no-tillage; residual nitrogen; Rice; Sampling techniques; Silt loam; silt loam soils; soil management; Soil science; Soil sciences; Soil water; Soils; Surficial geology; Tillage; Water conservation; Zea mays; Kansas; Soil science; Earth science
• ISSN: 0361-5995; 1435-0661
• DOI: 10.2136/sssaj2005.0253

Predicting in situ nitrogen (N) mineralization has been one of the greatest challenges to improving N management in agriculture. This study investigated the effect of tillage and residual N on soil N supplying capacity and evaluated the relationship between measured and estimated mineralizable N. The experiment was established in 1990 on a moderately well-drained Kennebec silt loam (Fine-silty, mixed, superactive mesic Cumulic Hapludoll) with continuous corn (Zea mays L.). The study was a split-split plot design replicated four times. The main plot treatment was tillage (no-tillage [NT] and conventional tillage [CT]), the subplot treatment was N source (manure and NH₄NO₃ fertilizer [F]), and the sub-subplot treatment was the length of residual period. Residual N was studied 1 yr after cessation of a 10-yr N application (R₁) and 6 yr after cessation of a 5-yr N application (R₆). Measured in situ N mineralization (N(min)), laboratory potentially mineralizable N (N₀), and estimated N mineralization under field conditions (N(estimated)) were evaluated. Nitrogen mineralization was studied in situ in an unplanted, sheltered area. Samples were collected from 0- to 5-, 5- to 15-, and 15- to 30-cm depths. No-tillage and manure significantly increased soil total N, N(min), and N₀. The combination of NT and manure significantly increased N₀ in both R₁ and R₆. High correlation was observed between N(min) and N(estimated) for 0 to 5 cm (r = 0.79) and for 0 to 30 cm (r = 0.77). No-tillage and manure sustained soil N 6 yr after discontinued N application. Potential mineralizable N, for site specific conditions could be used to estimate in situ N mineralization after adjustment to field conditions (soil water and temperature).