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Soil Nitrogen Cycling following Montane Forest Conversion in Central Sulawesi, Indonesia
Author(s) -
Corre Marife D.,
Dechert Georg,
Veldkamp Edzo
Publication year - 2006
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj2005.0061
Subject(s) - cycling , mineralization (soil science) , environmental science , nitrogen cycle , agroforestry , agronomy , soil carbon , nitrification , theobroma , nutrient cycle , ecosystem , rainforest , nitrogen , soil water , ecology , forestry , geography , chemistry , botany , biology , soil science , organic chemistry
The lower montane forest zone of Indonesia is undergoing rapid conversion of indigenous forests to agriculture. In this tropical region, however, the effects of forest conversion on soil N processes have not been investigated. Corn (Zea mays L.) and cacao ( Theobroma cacao L.)–coffee ( Coffea canephora Pierre ex Froehner) agroforestry are the main land use types in cleared lower montane forests in Central Sulawesi, Indonesia. Our main objective was to compare the soil N dynamics under agroforest systems and corn cultivation with indigenous forest. We measured the gross rates of N transformation processes using 15 N pool dilution. The agroforest systems and indigenous forests had higher gross N mineralization rates and faster turnover rates of NH 4 + and microbial N pools than the long‐term cultivated corn sites. Faster soil N turnover rates in agroforest systems suggest a more dynamic soil N cycling. Leguminous shade trees, which are important components of these agroforest systems, may have influenced the fast microbial N cycling through release of N‐rich root exudates and plant residues. Our results show that compared with corn, agroforestry is a better option in terms of sustainability in the N‐supplying capacity of the soil. In addition, we measured higher 15 NH 4 + recoveries than 15 NO 3 − recoveries after 15 min of 15 N addition in all our sites. Our measured rates of gross nitrification were very low to negligible, due to rapid disappearance of added 15 NO 3 − Such fast reaction of NO 3 − warrants further investigation, especially in tropical areas where 15 N studies are very few.