Abstract
This is a continuation of work during 2008-2009 where food web structure among soil fauna, mainly Collembola, Acari and other small Arthorpods was studied in different land-use systems in Kenya. Now we plan to extend the studies to other soil fauna groups (Nematoda, Oligochaeta and Insecta) and to microorganisms to get a holistic picture. We ask the questions: - How are soil organism communities in tropical agriculture influenced by different amounts and qualities of organic matter and different crops and cultivation intensity? - Is the soil organism food web more stable and resilient in agricultural soils with high levels of organic matter than in depleted soil? - Which species and groups get their nourishment directly from the growing crop through root consumption or indirectly though microorganisms that live from the roots and root exudates? ? Which species and groups live from the dead organic matter? The composition of the soil fauna will be analyzed by sampling of soil, extraction and determination. Microorganisms will be analyzed by fatty acid analysis PLFA. Trophic relations will be analyzed with mass spectrometer analyze of stable isotope ration of 13C/12C and 15N/14N in soil animals and in fatty acids that are markers of different microorganism groups. In field experiments with different levels of organic fertilizer application and soil cultivation the crop will be labeled with 13C and the excess of the isotope be followed through the food web.
Sweden