TITLE

Nitrogen Mineralization Dynamics under Different Moisture Regimes in Tropical Soils

AUTHOR(S)
Abera, Girma; Wolde-meskel, Endalkachew; Beyene, Sheleme; Bakken, Lars R.
PUB. DATE
October 2012
SOURCE
International Journal of Soil Science;2012, Vol. 7 Issue 4, p132
SOURCE TYPE
Academic Journal
DOC. TYPE
Article
ABSTRACT
This study was conducted to assess nitrogen (N) mineralization from Soil Organic Matter (SOM) in situ and in laboratory incubation under different soil moisture regimes. Andosol soils were sampled from coffee (CF) and crop (CP) land uses of southern Ethiopia. Extractable NO3--N and mineral N were strongly increased, while NH4+-N declined in response to soil moisture increase (from air dry to 100% FC, field capacity) during laboratory incubation. In situ extractable NO3--N and mineral N were strikingly low in December (dry) with both CF and CP. However, they were consistently greater during March to August due to more rain flushes, suggesting better N release during cropping season. Increasing soil moisture from air dry to 100% FG enhanced extractable NO3--N and mineral N of CF by 95.7 and 81.7%, respectively, while that of CP was increased by 58.7 and 46.4% respectively. By contrast, extractable NH4+-N declined by 82.9% with CF and by 87.0% with CP. The assessment of N mineralization in relation with soil moisture showed consistent trends both under in situ and laboratory methods. Indeed, the N mineralization of CF was about double to that of CP at 75-100% FC and during July-August (wet season). In contrast, average in situ N mineralization of CP was greater than CF, attributed to longer history of annual inputs of N-fertilizer and might be because of absence of actively competing plants with soil microorganisms. Generally, the knowledge of annual patterns of N mineralization in relation with soil moisture is necessary to synchronize crop N demands with plant-available N in the soil.
ACCESSION #
88876211

 

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