US: Biochar could replace unsustainable peat moss in greenhouse industry

Plant lovers are familiar with peat moss as the major component of potting mix, but harvest of the material is becoming unsustainable. Not only is peat being removed faster than it can re-form, its use in potting mix contributes to the release of carbon dioxide into the atmosphere.

"Peat bogs naturally store carbon. When peat moss is harvested, there's a transfer of a global carbon sink into a net source. That's because within a couple growing seasons, most of the peat moss from the potting mix is either mineralized by microbes or thrown out and decomposed. Either way, carbon dioxide is released," says Andrew Margenot, assistant professor in the Department of Crop Sciences.

In a recent study, Margenot and colleagues from the University of California, Davis investigated a material called biochar as an alternative to peat moss in potting mix. Similar to charcoal, biochar is produced through a process called pyrolysis, or heating to high temperatures in the absence of oxygen. And like charcoal, it can be derived from virtually any organic substance.

"In our study, we used one made from softwoods from selective logging. But biochars can be made from corn stover, switchgrass, and lots of other organic waste products," Margenot says. "Biochar could even be made from a greenhouse operation's own waste, if there are trimmings from plants or old peat moss." Margenot emphasizes that 'biochar' refers to a very broad class of material that can vary greatly in its properties depending on the pyrolysis temperature and the feedstock used.

Click here to read the complete article at: phys.org