Measuring plant-available silicon in rice paddies

Rice accumulates more silicon than any other nutrient in its tissues, which functions to protect the plant from a variety of stressors. Despite silicon's abundance in soil, most is usually unavailable to the plant. Measuring the amount of plant-available silicon is crucial to determine if a field could benefit from silicon fertilizer, but these measurements can be biased by soil type, the use of silicon fertilizers, and the extent of flooding in the rice paddies.

In a recent article published in the Soil Science Society of America Journal, researchers conducted a multi-year study of rice paddies subjected to different silicon fertilizers, including chemical fertilizers and silicon-rich rice husks, and operated under varying degrees of flooding. The team examined correlations between plant silicon concentrations and several soil silicon extraction methods.

The researchers found that a dilute calcium chloride extraction for 4 or 16 hours best predicted plant silicon concentrations irrespective of management. Other extractants were positively correlated with plant silicon but biased the amount of plant-available silicon when a silicate fertilizer was present.

Any fertilizer recommendation can be improved with the use of robust soil testing. This work moves the rice community closer toward robust plant-available silicon soil testing.