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Title: NITROGEN MINERALIZATION FROM A SOIL WITH DIFFERING N SUPPLY CAPACITIES

Author
item Mikha, Maysoon
item RICE, CHARLES - KANSAS STATE UNIVERSITY

Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 7/21/2004
Publication Date: 10/31/2004
Citation: Mikha, M.M., Rice, C.W. 2004. Nitrogen mineralization from a soil with differing N supply capacities. Agronomy Abstracts. Presented at the 2004 ASA-CSSA-SSSA International Annual Meeting. Oct. 31-Nov. 4, 2004. Seattle, WA.

Interpretive Summary:

Technical Abstract: Nitrogen mineralization is an important component of N supply for plant growth. Soil N supply capacity was investigated from an experiment one year after cessation of 10 yr of N application (R1) and 6 yr after cessation of 5 yr of N application (R6) from manure (M) and inorganic fertilizer (F) under no-tillage and conventional tillage. The experiment was established on a Kennebec silt loam with continuous dryland corn (Zea mays L.). Nitrogen mineralization under field conditions (Nmin), potentially mineralizable N with modification of the first-order exponential mineralization model (Nmodel), and plant N uptake (Nplant) were studied to determine which of these indices better described N availability for crop requirements. Nitrogen mineralization was studied under field condition by erecting shelter (90 x 90 cm) over a fallow area. No-tillage and manure significantly increased soil organic N and potentially mineralizable N. Six yr after discontinued N application, total N uptake from mineralized N represented about 81 and 66 kg N ha-1 for M and F, respectively. The field N mineralization (0-30 cm depth) estimate accounted for 38 and 22% of N uptake for M and F, respectively. The Nmodel predicted about 51% of the N mineralized that was taken up by the plant. In general, plant N uptake was a better prediction of crop N requirements.