Abstract
Previous results from a long-term grassland trial, located in south-east Ireland indicated conserved
(homeostatic) nutrient stoichiometry of the soil microbial biomass despite widely varying soil C:N:P
ratios. To determine whether this was associated with a change in microbial community structure, rather
than a change in microbial physiology, this study characterized the responses of below-ground microbial
and nematode community structure to P fertilization. The trial site maintained a range of P fertilisation
rates (0e30 kg P ha 1 yr 1) which had been applied since 1968 and soil samples were collected in spring
2009, autumn 2010 and spring 2011. The microbial biomass demonstrated homeostatic stoichiometry
over all sampling occasions, particularly of the C:P ratio, despite a 50-fold difference in soil solution C:P
ratio. However, microbial and nematode community structure also varied with P fertilisation, indicating
that nutrient ratios are maintained even though there were changes in microbial community structure. P
fertilization induced a shift from fungal to bacterial dominated decomposition pathways, as indicated by
the proportion of bacterial-feeding to fungal-feeding nematodes and bacterial: fungal phospholipid fatty
acids (PLFAs). The altered microbial community structure was considered to result from bottom-up
control of nutrient quality and quantity by altered vegetation structure and fertilizer inputs, as well as
top-down pressures from the nematode community.
2014 Elsevier Ltd. All rights reserved.
Original language | English |
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Pages (from-to) | 94 - 101 |
Number of pages | 8 |
Journal | Soil Biology and Biochemistry |
Volume | 75 |
DOIs | |
Publication status | Print publication - Aug 2014 |
Bibliographical note
10233241023321
Keywords
- Bacterial:fungal ratio
- Bottom-up control
- Nematodes
- Phosphorus
- Soil microbial biomass
- Top-down control