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Assessing the vulnerability of organic matter to C mineralisation in pasture and cropping soils of New Zealand
- Source :
- Soil Research. 56:481
- Publication Year :
- 2018
- Publisher :
- CSIRO Publishing, 2018.
-
Abstract
- In New Zealand, pastoral soils have substantial organic carbon (OC) stocks, which may be vulnerable to loss from disturbance and environmental perturbations. We assessed OC vulnerability using two approaches. For the first approach, we postulated that the OC deficit of continuously cropped soils relative to nearby pastoral soils would provide a measure of the quantity of potentially vulnerable OC in pastures. As a test, soils were sampled to a depth of 15 cm at 149 sites and the total organic carbon (TOC) and particulate organic carbon (POC) contents were measured. The second approach involved measurement of OC mineralisation in a laboratory assay (98 day aerobic incubation at 25°C). For the pastoral soils, the mean TOC and POC was about twice that of the cropped soils. On average, 89% more OC was mineralised from the pastoral soils compared with the cropped counterparts. However, the quantity of OC mineralised in pasture soils was small relative to the potential for OC loss inferred from the difference in TOC between pastoral and cropped soils. Carbon mineralisation was explained using a two-pool exponential model with rate constants of the ‘fast’ and ‘slow’ pools equating to 0.36 ± 0.155 and 0.007 ± 0.003 day–1 respectively. The larger, slow OC pool correlated strongly with hot water extractable OC whereas the fast pool was related to OC extracted using cold water. Our results suggest that water extraction (using cold and hot water) can provide a rapid estimate of the quantity of mineralisable OC across a wide range of New Zealand soils.
- Subjects :
- Total organic carbon
chemistry.chemical_classification
geography
Particulate organic carbon
geography.geographical_feature_category
010504 meteorology & atmospheric sciences
Soil Science
chemistry.chemical_element
Water extraction
04 agricultural and veterinary sciences
Environmental Science (miscellaneous)
01 natural sciences
Pasture
Agronomy
chemistry
Soil water
040103 agronomy & agriculture
0401 agriculture, forestry, and fisheries
Environmental science
Organic matter
Cropping
Carbon
0105 earth and related environmental sciences
Earth-Surface Processes
Subjects
Details
- ISSN :
- 1838675X
- Volume :
- 56
- Database :
- OpenAIRE
- Journal :
- Soil Research
- Accession number :
- edsair.doi...........0f3dee0778455a16dded9674a77a256f
- Full Text :
- https://doi.org/10.1071/sr17148