Dissertation
LABILE ORGANIC CARBON IN SOIL PROFILES AFTER LONG-TERM NO-TILLAGE: LABORATORY TO FIELD-SCALE AND COMPARISON WITH NATIVE PRAIRIE
Doctor of Philosophy (PhD), Washington State University
01/2020
Handle:
https://hdl.handle.net/2376/100065
Abstract
Labile soil organic carbon (SOC) is essential for nutrient cycling and is also sensitive to land management and environment changes. Our project goals are to investigate SOC quantities and qualities from field-scale to soil profiles (0-153 cm) under no-tillage (NT) and to compare SOC fraction composition in the surface 20 cm under conventional tillage (CT) and native prairie (NP). Additionally, we aim to bridge laboratory analyses with field-scale measurement to further comprehend soil-atmosphere carbon exchange. Soil samples with different initial SOC levels at various depths from NT, CT and NP sites were incubated for up to 350 days. Random forest (RF) modeling using external variables of soil properties, crop input and terrain attributes was developed to predict labile SOC stocks for 183 geo-reference points across a 37-ha NT field. Our results showed that soil labile carbon characterized and quantified by mean residence time (MRT) of 5 days, 60 days and 2 years and SOC rejuvenate index derived from MRT-defined pools were sensitive to management. No-tillage increased SOC pools with MRT of 60 days and 2 years compared to CT and NP, and improved soil quality better than CT. The labile carbon concentration increased as MRT increased and stable carbon (MRT>2 years) comprised >60% of SOC, regardless of initial SOC levels and land management. MRT-defined labile SOC fractions were positively correlated with water extractable carbon, permanganate oxidizable carbon and total phospholipid fatty acid (p<0.01), and also were a joint effect of soil properties, crop and terrain attributes more closely related with hydrological processes and temperature. The mean estimated stocks of carbon with MRT = 5 days and 60 days across the NT field for 0-30 cm were 0.55±0.03 and 2.01±0.14 Mg C/ha, respectively. Annually, 1.08 Mg C/ha of SOC was estimated to be lost after partitioning the eddy covariance flux measurements and accounted for 42% of estimated total labile SOC stocks (2.56 Mg C/ha) in surface 30 cm. We concluded that MRT-defined labile pools, total mineralized carbon within 60 days, and POXC are good indicators for soil quality assessment and are also useful for predicting potential annual SOC loss.
Metrics
65 File views/ downloads
41 Record Views
Details
- Title
- LABILE ORGANIC CARBON IN SOIL PROFILES AFTER LONG-TERM NO-TILLAGE: LABORATORY TO FIELD-SCALE AND COMPARISON WITH NATIVE PRAIRIE
- Creators
- Qiuping Peng
- Contributors
- David Rhys Huggins (Advisor)Lynne Alane Carpenter-Boggs (Committee Member)David Joseph Brown (Committee Member)Claudio Osvaldo Stockle (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Crop and Soil Sciences, Department of
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Number of pages
- 260
- Identifiers
- 99900581612501842
- Language
- English
- Resource Type
- Dissertation