Thesis
Root decomposition and annual changes in soil profile carbon in a hybrid poplar-switchgrass intercropping system
Washington State University
Master of Science (MS), Washington State University
2013
Handle:
https://hdl.handle.net/2376/102470
Abstract
As the population of the world has grown and greater numbers of people have increased their affluence, demand for energy has grown accordingly. With an increased demand for energy, exploitation of fossil fuel reserves has grown along with the associated environmental, social and economic impacts. Recently, research into alternative fuel sources has come to the forefront of the public policy debate. Amongst this debate is the topic of biofuels and energy sources derived from cultivated biomass cropping systems. Biomass production utilizing tree and perennial grasses are of particular interest due to these systems ability to produce large quantities of biomass while contributing significant amounts of carbon to the soil profile; by removing carbon from the atmosphere. These systems have the potential to offset greenhouse gases, increase soil carbon levels and provide biomass. Additionally, many of the crop species being studied for fuel production can be cultivated on marginal soils, thus negating the possibility of displacing food production in the interest of energy demand. In this study we examined an intercropping system of a perennial warm-season grass and fast-growing hybrid poplar trees. Two switchgrass ecotypes were intercropped with two hybrid poplar clones in a Randomized Complete Block experiment and annual changes in soil profile carbon, nitrogen and 13C were measured. In addition, a 1-year study of switchgrass root decomposition was carried out to determine relative contributions of root turnover to the soil organic carbon pool. Lastly, a laboratory study was conducted to determine if a byproduct of switchgrass pyrolysis, biochar, and another biofuel byproduct, brassica seed meal, could effectively be utilized to suppress carbon mineralization in two contrasting soils common to the inland Northwest. The results of these studies indicate changes in soil organic carbon and 13C is dependent upon switchgrass cultivar, however root decomposition dynamics is more strongly associated with root depth rather than switchgrass cultivar. The degree of CO2 suppression using biochar and seed meal was strongly dependent upon seed meal and soil type, and to a lesser extent the presence of biochar.
Metrics
3 File views/ downloads
8 Record Views
Details
- Title
- Root decomposition and annual changes in soil profile carbon in a hybrid poplar-switchgrass intercropping system
- Creators
- Alex Reed Crump
- Contributors
- Jeffrey L. Smith (Degree Supervisor)
- Awarding Institution
- Washington State University
- Academic Unit
- Crop and Soil Sciences, Department of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University; [Pullman, Washington] :
- Identifiers
- 99900525094001842
- Language
- English
- Resource Type
- Thesis