**Author details**

refine not only the model end products, but also the underlying assumptions that are relied

Carbon storage potential on the plantation scale in productive tropical cultivated systems is high when transitioning into conservation agriculture, especially when the deep soil profile is considered. Deep soil carbon increases, attributable to fast growing deep‐rooted perennial grasses, led to a high belowground carbon sequestration potential (4.1 ± 1.8 and 22.5 ± 4.9 Gg C/yr in the surface and deep soils, respectively) if the average yearly increase of soil carbon at field 718 is generalized across similar Pulehu soils at the HC&S plantation. Taking mod‐ eled soil carbon stocks in the surface soils and scaling similarly gave 3.3 Gg C/yr from the SoilR model and 1.9 Gg C/yr from the ALMANAC model. However, much lower estimates were found when the deep soils were projected forward (only 1.3 Gg C/yr estimated by the ALMANAC model). As SoilR requires more fraction data from the deeper profile, it will be interesting to see if SoilR consistently has a greater estimate and ALMANAC a lower estimate of soil carbon sequestration. Nonetheless, these results point to a large potential for carbon storage through conversion to conservation agriculture; if monetized, these carbon storage potentials could be a huge prospective boon to the value of HC&S as a bioenergy site with

As indicated by the density fractionation results from commercial field 718, soil carbon storage is likely driven by mineral sorption in our system. However, there is need to refine our under‐ standing of mineral changes across such a heterogeneous landscape, with continued density fractionation and iron/aluminum oxide measurements expected to better explain variations in soil carbon storage across HC&S. The estimated sequestration potentials will also need further improvement through comparison of our other field trials to determine if geospatial varia‐ tions in soil texture and mineralogy will affect total carbon sequestration potentials across this heterogeneous landscape. Through continued and more detailed mineralogy and the addition of detailed climate, net primary productivity, and belowground biomass data, we expect to uncover relationships between the many factors controlling soil carbon sequestration in this system. Determination of better metrics and relationships of soil properties to carbon seques‐ tration across the heterogeneous landscape of HC&S will enable more accurate projection of carbon sequestration potentials in Hawaii and other similar tropical perennial systems.

We thank Mae Nakahata and Hawaii Commercial & Sugar workers for their help with access, research priorities, and field work, and Richard Ogoshi and Andrew Hashimoto for field trial design and implementation and funding support. Preparation of this chapter was supported by the USDA‐ARS, Grassland, Soil and Water Research Laboratory, and Texas A&M AgriLife Research, Temple, TX, through Specific Cooperative Agreement: 58‐6206‐1‐053, and is funded

on to understand soil carbon sequestration and storage in the tropics.

**3. Conclusion**

166 Recent Advances in Carbon Capture and Storage

proper soil and harvest management.

**Acknowledgements**

Jon M. Wells1 , Susan E. Crow1 \*, Manyowa N. Meki2 , Carlos A. Sierra3 , Kimberly M. Carlson1 , Adel Youkhana1 , Daniel Richardson1 and Lauren Deem1

\*Address all correspondence to: crows@hawaii.edu

1 Natural Resources and Environmental Management Department, University of Hawaii at Manoa, Honolulu, HI, USA

2 Texas A&M AgriLife Research, Blackland Research and Extension Center, Temple, TX, USA

3 Max Plank Institute for Biogeochemistry, Jena, Germany

#### **References**


[24] Wendt JW, Hauser S. An equivalent soil mass procedure for monitoring soil organic car‐ bon in multiple soil layers. European Journal of Soil Science. 2013;64(1):58–65.

[10] Cotrufo MF, Soong JL, Horton AJ, Campbell EE, Haddix ML, Wall DH, et al. Formation of soil organic matter via biochemical and physical pathways of litter mass loss. Nature

[11] Rasse DP, Rumpel C, Dignac MF. Is soil carbon mostly root carbon? Mechanisms for a

[12] Plaza C, Courtier‐Murias D, Fernández JM, Polo A, Simpson AJ. Physical, chemical, and biochemical mechanisms of soil organic matter stabilization under conservation tillage systems: A central role for microbes and microbial by‐products in C sequestration. Soil

[13] O'Brien SL, Jastrow JD, Grimley DA, Gonzalez‐Meler MA. Edaphic controls on soil organic carbon stocks in restored grasslands. Geoderma. 2015;251–252:117–23.

[14] Marín‐Spiotta E, Gruley KE, Crawford J, Atkinson EE, Miesel JR, Greene S, et al. Paradigm shifts in soil organic matter research affect interpretations of aquatic car‐ bon cycling: Transcending disciplinary and ecosystem boundaries. Biogeochemistry.

[15] Schmidt MWI, Torn MS, Abiven S, Dittmar T, Guggenberger G, Janssens IA, et al. Persistence of soil organic matter as an ecosystem property. Nature. 2011;478(7367):49–56.

[16] Lehmann J, Kleber M. The contentious nature of soil organic matter. Nature. 2015;

[17] Masoom H, Courtier‐Murias D, Farooq H, Soong R, Kelleher BP, Zhang C, et al. Soil organic matter in its Native State: Unravelling the most complex biomaterial on earth.

[18] Palm C, Blanco‐Canqui H, DeClerck F, Gatere L, Grace P. Conservation agricul‐ ture and ecosystem services: An overview. Agriculture, Ecosystems & Environment.

[19] Davis SC, Boddey RM, Alves BJR, Cowie AL, George BH, Ogle SM, et al. Management

[20] Mutuo PK, Cadisch G, Albrecht A, Palm CA, Verchot L. Potential of agroforestry for car‐ bon sequestration and mitigation of greenhouse gas emissions from soils in the tropics.

[21] Anderson‐Teixeira KJ, Masters MD, Black CK, Zeri M, Hussain MZ, Bernacchi CJ, et al. Altered belowground carbon cycling following land‐use change to perennial bioenergy

[22] Davidson EA, Ackerman IL. Changes in soil carbon inventories following cultivation of

[23] Gifford RM, Roderick ML. Soil carbon stocks and bulk density: Spatial or cumulative mass coordinates as a basis of expression? Global Change Biology. 2003;9(11):1507–14.

swing potential for bioenergy crops. GCB Bioenergy. 2013;5(6):623–38.

specific stabilisation. Plant and Soil. 2005;269(1):341–56.

Environmental Science & Technology. 2016;50(4):1670–80.

Nutrient Cycling in Agroecosystems. 2005;71(1):43–54.

previously untilled soils. Biogeochemistry. 1993;20(3):161–93.

crops. Ecosystems. 2013;16(3):508–20.

Biology and Biochemistry. 2013;57:124–34.

Geosci. 2015;8(10):776–9.

168 Recent Advances in Carbon Capture and Storage

2014;117(2):279–97.

528(7580):60–8.

2014;187:87–105.


**Provisional chapter**
