Abstract
Grassland ecosystems in south-eastern Australia are important for dairy and livestock farming. Their productivity relies heavily on water availability, as well as the ecosystem services provided by soil microbial communities including carbon and nutrient cycling. Management practices such as compost application are being encouraged as a means to improve both soil water holding capacity and fertility, thereby buffering against the impacts of increasing climate variability. Such buffering consists of two complementary processes: resistance, which measures the ability of an ecosystem to maintain community structure and function during a period of stress (such as drying); and resilience, which measures the ability of an ecosystem to recover community structure and function post-stress. We investigated the effects of compost on the resistance and resilience of the grassland soil ecosystem under drying and drying with rewetting events, in a terrestrial model ecosystem. Overall, compost addition led to an increase in soil moisture, greater plant available P and higher plant δ15N. Soil C:nutrient ratios, mineral N content (NH4+ and NO3-) and soil microbial PLFA composition were similar between amended and unamended soils. Rainfall treatment led to differences in soil moisture, plant above-ground and below-ground biomass, plant δ15N, soil mineral N content (NH4+ and NO3-) and microbial biomass C, N and P composition but had no effects on soil C:nutrient ratios, plant available P and soil microbial PLFA composition. There was little interaction between rainfall and compost. Generally, the soil microbial community was resistant and resilient to fluctuations in rainfall regardless of compost amendment. However, these properties of the soil microbial community were translated to resilience and not resistance in soil functions. Overall, the results below-ground showed much greater response to rainfall than compost amendment. Water was the key factor shaping the soil microbial community, and nutrients were not strong co-limiting factors. Future projections of increasing rainfall variability will have important below-ground functional consequences in the grassland, including altered nutrient cycling.
Original language | English |
---|---|
Pages (from-to) | 58-66 |
Number of pages | 9 |
Journal | Soil Biology and Biochemistry |
Volume | 81 |
DOIs | |
Publication status | Published - Feb 2015 |
Externally published | Yes |
Bibliographical note
Funding Information:This work was supported by funding from the Monash Sustainability Institute Australia , Brown Coal Innovation Australia and the Australian Research Council (ARC). NEL wishes to thank Pablo Galaviz, Mattia Pierangelini, Alicia Brown, Mani Shresta for assisting field and lab work. TRC also thanks the ARC for the award of a Future Fellowship (FT120100463). We thank Kate Scow and two anonymous reviewers for their detailed and constructive suggestions for the manuscript's improvement.
Publisher Copyright:
© 2014 Elsevier Ltd.
Keywords
- 13-C NMR
- Carbon cycling
- Grassland soil microbial community
- Microbial activity
- PLFA