Evaluation of three field-based methods for quantifying soil carbon

Citation: Izaurralde, Roberto C., Charles W. Rice, Lucian Wielopolski, Michael H. Ebinger, James B. Reeves Iii, Allison M. Thomson, Ronny Harris, et al. “Evaluation of Three Field-Based Methods for Quantifying Soil Carbon.” PLOS ONE 8, no. 1 (January 31, 2013): e55560. https://doi.org/10.1371/journal.pone.0055560.Three advanced technologies to measure soil carbon (C) density (g C mˉ²) are deployed in the field and the results compared against those obtained by the dry combustion (DC) method. The advanced methods are: a) Laser Induced Breakdown Spectroscopy (LIBS), b) Diffuse Reflectance Fourier Transform Infrared Spectroscopy (DRIFTS), and c) Inelastic Neutron Scattering (INS). The measurements and soil samples were acquired at Beltsville, MD, USA and at Centro International para el Mejoramiento del Maı´z y el Trigo (CIMMYT) at El Bata´n, Mexico. At Beltsville, soil samples were extracted at three depth intervals (0–5, 5–15, and 15–30 cm) and processed for analysis in the field with the LIBS and DRIFTS instruments. The INS instrument determined soil C density to a depth of 30 cm via scanning and stationary measurements. Subsequently, soil core samples were analyzed in the laboratory for soil bulk density (kg mˉ³), C concentration (g kgˉ¹) by DC, and results reported as soil C density (kg mˉ²). Results from each technique were derived independently and contributed to a blind test against results from the reference (DC) method. A similar procedure was employed at CIMMYT in Mexico employing but only with the LIBS and DRIFTS instruments. Following conversion to common units, we found that the LIBS, DRIFTS, and INS results can be compared directly with those obtained by the DC method. The first two methods and the standard DC require soil sampling and need soil bulk density information to convert soil C concentrations to soil C densities while the INS method does not require soil sampling. We conclude that, in comparison with the DC method, the three instruments (a) showed acceptable performances although further work is needed to improve calibration techniques and (b) demonstrated their portability and their capacity to perform under field conditions

Bioenergy and agricultural research for development: bioenergy and agriculture promises and challenges

"Converting agriculture to produce energy as well as food has become an important and well-funded global research goal as petroleum reserves fall and fuel prices rise. But the use of crop biomass—both grain and other plant parts—as a raw material for bioenergy production may compete with food and feed supplies and remove valuable plant residues that help sustain soil productivity and structure and avoid erosion. Agricultural research can mitigate these trade-offs by enhancing the biomass traits of dual-purpose food crops, developing new biomass crops for marginal lands where there is less competition with food crops, and developing sustainable livestock management systems that are less dependent on biomass residuals for feeds... The breeding of new cultivars for the biofuel market may open the opportunity for a whole new paradigm in public-private partnerships. Public research may focus on tapping potential plant genetic resources and initial trait genetic enhancement that will feed into either public or private breeding programs worldwide. International public organizations, such as the CGIAR, may serve as conduits of new knowledge and technology to small-scale farmers, particularly in resource-poor farming areas of the developing world." from TextAgriculture, Crop genetic diversity, Food crops, livestock management, Public-private partnerships, plant genetic resources, plant breeding, Small-scale farmers, Technological innovation,

Schematic diagram and field setup of Laser Induced Breakdown Spectroscopy (LIBS) instrument: (a) schematic diagram and (b) picture of SUV-portable LIBS equipment used in this study.

<p>Schematic diagram and field setup of Laser Induced Breakdown Spectroscopy (LIBS) instrument: (a) schematic diagram and (b) picture of SUV-portable LIBS equipment used in this study.</p

Spectra characteristics and field setup of Diffuse Reflectance Fourier Transform Infrared Spectroscopy (DRIFTS) instrument: (a) Diagram of diffuse reflection of IR light by soil sample, (b) SUV-portable mid-infrared (MIR) spectrometer used in this study, (c) typical mid-infrared diffuse reflectance spectra from soil and (d) near-infrared diffuse reflectance spectra from soil.

<p>Spectra characteristics and field setup of Diffuse Reflectance Fourier Transform Infrared Spectroscopy (DRIFTS) instrument: (a) Diagram of diffuse reflection of IR light by soil sample, (b) SUV-portable mid-infrared (MIR) spectrometer used in this study, (c) typical mid-infrared diffuse reflectance spectra from soil and (d) near-infrared diffuse reflectance spectra from soil.</p

Deployment modes, schematic diagram, and field setup of Inelastic Neutron Scattering (INS) instrument: (a) The three-detector INS instrument in its various deployment modes: (a) Schematic diagram of a stationary INS instrument for soil studies, (b) the INS instrument used in this study, mounted on a cart for operation in field-scanning mode, and (c) INS instrument being towed behind a tractor during a field scan.

<p>Deployment modes, schematic diagram, and field setup of Inelastic Neutron Scattering (INS) instrument: (a) The three-detector INS instrument in its various deployment modes: (a) Schematic diagram of a stationary INS instrument for soil studies, (b) the INS instrument used in this study, mounted on a cart for operation in field-scanning mode, and (c) INS instrument being towed behind a tractor during a field scan.</p