USA: Scientists have investigated different components of variation in soil at diverse scales ranging from the nanoscale to entire biomes in order to improve predictions of soil processes and subsequently land use.
Soil variation occurs across multiple geographic scales ranging from vast climatic regions of the Earth to a 50 acre farm field to the molecular world of soil nano-particles in a pinch of soil.
Though many approaches have been used to examine soil variation at these diverse scales, there is a common difficulty among methods in separating out random variations from systematic variations.
Some of the variation observed in, say, a desert community or a handful of soil is random, but other variation is predictable (systematic) based on variables such as landscape position, climate, or time of the year.
The new methodological developments will better enable scientists to separate out these different sources of variation by examining soil variability over a range of scales, which is important for linking soil properties with soil processes.
These linkages have important predictive capacities, such as forecasting corn yields based on soil characteristics, or understanding where microorganisms live in soil and how human alteration to certain soil properties affects their livelihood.
The soil analysis was done by scientists from USDA-ARS-NSTL in Iowa, The University of Tennessee, and E. T. S. Ingenieros Agronomos in Spain, who assembled a collection of 12 papers covering a range of original approaches for assessing soil variability across multiple scales.
A variety of multi-scale methods are described in these papers and some authors compared the performance of different approaches.
The methodologies employed include a variety of sophisticated mathematical approaches including geostatistics, and fractals and multi-fractals, to name a few.
The authors then applied these different multi-scale methods to diverse data sets including soil pore shapes, soil aggregates, water content, rate of water movement, gas fluxes, corn yields, geochemical data, and remote sensing data.
According to researcher Dr. Sally Logsdon of the USDA-ARS, National Soil Tilth Laboratory, Ames, IA, “Understanding the interrelationships between physical, chemical, and biological factors at different scales is essential for research in agriculture, engineering, hydrology, and the environment.”
“Future research should examine how to better mesh together soil data and predictions across landscape position and time scales,” she added.