London, Apr 29 : Cornell researchers have taken a closer look at soil than anyone else - at a scale of 50 nanometers - and revealed that though it may look similar to the naked eye, soil has an 'incredible' variety.
Till date, the composition of soil humus (or the organic component of soil, formed by the decomposition of leaves and other plant material by soil microorganisms) looked extremely similar.
But a new study has suggested that the knowledge of the structure and detailed composition of soil carbon may help in giving a better understanding of the chemical processes involved in cycling organic matter in soil. In fact, using the findings may even explain the outcome if the soil components get wet, warm or cool how soils impound carbon, which has implications for climate change.
"There is this incredible nanoscale heterogeneity of organic matter in terms of soil. None of these compounds that you can see on a nanoscale level looks anything close to the sum of the entire organic matter," Nature quoted Johannes Lehmann, a Cornell associate professor of crop and soil sciences and lead author of the study, as saying.
The researchers used X-ray spectromicroscopy method developed by physicists at the State University of New York, Stony Brook, to take the soil measurements at the National Synchrotron Light Source at Brookhaven National Laboratory. With this method, the researchers were able to spot the forms of organic carbon in the samples. The composition of soil differed from geographically as well and it was found that within spaces separated by mere micrometers, soils from different locations displayed striking contrast in their compositions.
For example, the compounds that "hang on the right and left of a clay mineral may be completely different," said Lehmann.
The team of researchers successfully identified the origins of some of the nano-sized compounds, discovering that some of them were even microbe excretions and decomposed leaves. They also identified patterns of where types of compounds can be easily found at the nanoscale.
"Now we can start locating certain compounds. We find black carbon as distinct particles in pores, whereas we find microbial products smeared around surfaces of minerals," said Lehmann.
He said that now, it will be possible for researchers to break soil down, separate compounds, conduct experiments on individual compounds and better understand the interactions.
The research was published in the latest issue of Nature Geoscience.