Soil fertility promotes decomposition rate of nutrient poor, but not nutrient rich litter through nitrogen transfer

• Published in: Plant and soil 2017-03, Vol.412 (1/2), p.397-411
• Main Authors: Bonanomi, Giuliano, Cesarano, Gaspare, Gaglione, Salvatore A., Ippolito, Francesca, Sarker, Tushar, Rao, Maria A.
• Format: Article
• Language: English
• Subjects: Biodegradation; Biomedical and Life Sciences; Decay; Decomposition; Ecological research; Ecology; Environmental aspects; Life Sciences; Litter; Nitrogen; Nitrogen (Chemical element); Nutrients; Physiological aspects; Plant Physiology; Plant Sciences; Plant-soil relationships; Regular Article; Soil fertility; Soil Science & Conservation; Soil types; Studies; Substrates; Terrestrial ecosystems
• ISSN: 0032-079X; 1573-5036
• DOI: 10.1007/s11104-016-3072-1

Background and aims: Litter decomposition is a critical process in terrestrial ecosystems and understanding the effects of soil fertility on the litter decay rate is of great ecological relevance. Here we test the hypothesis that N transfer from soil to litter will promote the decay rate of N poor but not N rich litter types. Methods: Ten organic substrates, encompassing a wide range of biochemical quality in terms of C/N and lignin/N ratios, were decomposed in microcosms over three soil types with different N content, but inoculated with the same microbiome. Organic substrates were characterized for mass loss, C and N content to assess N transfer from soil to litter. Results: The decay rate response to soil fertility was related to their initial N content: positive for substrates with little initial N content and not significant for N rich plant residues. A significant for N transfer, generally larger from N rich soil to N poor substrates, was found. Litter C/N and lignin/N ratios showed variable relationships with the litter decay according with the soil fertility gradient, with positive and negative correlations in N rich and N poor soils, respectively. Conclusions: Our study demonstrated that the decomposition of N rich litter proceeded irrespective of soil fertility while the decay rate of N poor substrates, either lignin poor or rich, was controlled by soil fertility likely as a result of N transfer. Litter C/N and lignin/N ratios were reliable indicators of litter quality to predict their decay rate in N poor soil, but not in N rich soils.