Biological impacts on silicon availability and cycling in agricultural plant-soil systems

The role of biota for silicon (Si) cycling in agricultural plant-soil systems has gained much attention in the last decades. Siliceous structures formed by organisms, that is, biogenic silica (BSi), play a key role in (i) linking global Si and carbon cycles and (ii) controlling bioavailability of Si in soils as BSi generally is much more soluble compared to silicate minerals. Si availability in soils is crucial for plant growth, because Si accumulation in plants increases their resistance against abiotic (e.g., drought) and biotic (e.g., fungal infection) stress. Thus, knowledge of biological impacts on Si bioavailability is of special importance for agricultural plant-soil systems. In this chapter, we give a comprehensive overview of the role of various organisms from plants to protists and corresponding BSi pools in Si cycling. Implications for ecosystem functioning and services of agricultural plant-soil systems are discussed and future directions outlined.