Effect of active forms of silicon on soil fertility: a model experiment

Abstract

Soil fertility is a key parameter of agroecosystem productivity and crop yields. Every year, 12 million hectares of soil are lost due to degradation globally. The application of soil ameliorants, proper fertilization, and optimal crop growing techniques help maintain soil fertility. The use of silicon-containing ameliorants is known to improve a number of soil characteristics that control the quality of agricultural land; however, their effects on different soil types are understudied. The research goal was to study the effect of amorphous silica (SiO₂) on the sorption of nutrients and microbial activity in soddy-podzolic soil, gray forest soil, and southern chernozem in a model experiment. Finely dispersed silica was added to samples of arable horizons of these soils at 200, 500, and 1000 kg ha. After a two-month incubation period, the soils were analyzed for pH, organic matter content, cation exchange capacity, plant-available phosphorus and potassium, and catalase activity. In all three soils, the application of SiO₂ improved sorption capacity, microbial activity, and the content of plant-available K and P while reducing their leaching, and also reduced the leaching of ammonium ions. In the soddy-podzolic soil, an increase of organic matter was observed which was likely associated with enhanced microbial activity. It is assumed that the effect of silica is due to increasing concentration of monomers and polymers of silicic acid as a result of its high solubility. Monosilicic acid influences chemical and biological processes, including microbial activity, while polymeric forms of silicic acid affect the aggregation of soil particles. Thus, the application of active forms of silicon initiates direct and indirect processes that enhance the fertility of different soil types.