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Meetings - Paper

322-8 A Comparison of Methods to Estimate N Mineralization in Soils Amended with Poultry Litter.

Poster Number 1253

2014-11-04: Session Time 2:00 PM-4:00 PM
Author: John Rema,
Author: Miguel Cabrera,
Presenting Author: Nicolas Wyngaard,

Fertilization with poultry litter (PL) may increase the nitrogen (N) mineralization potential (N0) of the soil. Due to the long time required to measure N0, short-term biological and chemical indexes have been developed to estimate it. The objective of this study was to quantify the change in N0 in soils amended with PL and to evaluate the validity of the use of N0 estimators in PL amended soils.

Four sites receiving long-term (>10 years) fertilization treatments (PL vs. Inorganic) were sampled: Delaware 1, Delaware 2, Iowa and Georgia (11.8%, 14.5%, 29.2% and 39.9% clay respectively). Samples were incubated in an aerobic open system for 6 months with bi-weekly leaching to measure N0. Different N0 estimators were evaluated: anaerobic incubation for 7 days (Nan), Illinois soil test analysis (ISNT), extraction with hot KCl,  distillation with NaOH or phosphate-borate (PB) and quantification of N in the particulate fraction (N-PF).

The response of N0 to N sources was highly associated with soil texture. In Delaware 1 N0 was not modified, while in Delaware 2, Iowa and Georgia N0 it was increased by PL fertilization (34, 99 and 166 mg N kg-1 respectively). Regarding the N0 estimators, hot KCl and ISNT underestimated N0 in PL treatments, while PB showed a low association to N0 (R2=0.58). N-PF presented a high variability. From the evaluated methods, Nan and NaOH are recommended, as they showed the best correlation with N0 (R2= 0.98 and 0.89 respectively), low variability and were not biased by the fertilization treatments.


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