Productivity and carbon accumulation in three varieties of Glycine max (L.) Merill grown on soil amended with different levels of silica

Increased plant vigor is advantageous to crops in the face of climate change. Crops with high vigor have higher biomass and carbon accumulation, hence mitigating climate change. Silicon exerts beneficial effects in stimulating plant growth, boosts plant biomass accumulation and crop yield. Soybean is one of the major crops cultivated for both industrial and food purposes on every continent. This study investigated the effect of soil amendment with powdered silica on the growth, biomass accumulation and carbon assimilation of soybean. Seeds of three varieties of soybean, TGX1904, TMX1441 and MAX1951 were sown in polythene pots filled with garden soil after which the plants were treated with three levels of powdered silica (250, 500 and 750g) two weeks after planting in a 3 x 4 x 3 completely randomized design. Parameters evaluated include growth characters, reproductive characters, protein and chlorophyll content, soil organic carbon sequestered and sequestered CO2 equivalent. Results showed amendment with silica significantly increased plant growth with the 750g silica treatment producing the longest plants and highest numbers of leaf of 13.66±0.17cm and 33.00±1.41 respectively compared to the control setup with mean height of 12.06±0.15cm and 22.39±0.85 leaves (p < 0.05). Similarly, the amended soils produced significantly higher numbers of flowers, pods and 100 seed weight with the 750g amendment having 22.33±3.27 flowers compared to 7.22±2.99 flowers in the control, and 38.00±2.91 pods in the 500g amendment compared with 19.67±2.28 pods in the control. In addition, the dry weight of the MAX1951 variety increased with increasing concentration of silica however, the 750g treatment of TMX1441 consistently recorded the highest dry weight (11.20g), total sequestered carbon (5.60g) and sequestered CO2 equivalent (20.60g). Although treatment with silica did not significantly affect protein and chlorophyll content, it had significant positive impact on biomass and yield traits as well as sequestered carbon.