Heat improves silicon availability in mineral soils

Altered fire regimes as a response to climate change are significantly affecting terrestrial ecosystems and biogeochemical cycles. In this context, not only natural fires but also anthropogenic fires like rice straw burning have to be considered. While heat effects of fire on some nutrient cycles (e.g., carbon, nitrogen, phosphorus) have been well-studied, little is known about consequences of heat for the silicon (Si) cycle. There is some information that heat increases the release of Si from soil organic matter. However, nothing is known about the effect of heat on Si availability in mineral soils to the best of our knowledge. We analyzed the effect of heat on Si availability in six different mineral soils. Our data show that heat is increasing Si availability (Mehlich-3 extractable) of all tested soils. The same pattern was found for amorphous Si (alkaline extraction) for most of these soils. Consequently, heated soils might represent a strong and immediate source for plant available Si. Ecosystem characteristics (e.g., vegetation, soil type) that affect uptake-leaching balances determine the further fate of the released Si. In summary, heat might affect Si cycling not only by strongly increasing Si availability in soil organic matter but also in mineral soils.

Automated summary

Climate change-induced altered fire regimes are significantly impacting terrestrial ecosystems and biogeochemical cycles. In addition to natural fires, anthropogenic fires like rice straw burning must also be considered. While the heat effects of fire on nutrient cycles such as carbon, nitrogen, and phosphorus are well-studied, the consequences of heat on the silicon cycle remain largely unknown. Heat has been shown to increase the release of silicon from soil organic matter, but the effect of heat on silicon availability in mineral soils is still unclear.