Most fertilizers are typically applied to soil in liquid, powder, or granule form. In most cases, the substance either leaches into the water table or evaporates into the atmosphere before releasing its full nutrient payload. That means added expense and work for farmers who must perform multiple fertilizer applications. Scientists think one solution could be a slow-release fertilizer in the form of tiny glass beads.
“The results show that glass fertilizers can be tailored to plant needs, slowly and sustainably releasing nutrients to boost productivity without harming soil quality,” said Danilo Manzani, co-author of the new research in ACS Agricultural Science & Technology.
Manzani and his team synthesized glass consisting of several micro- and macronutrients, such as phosphorus, potassium and calcium. They ground the glass into small (less than 0.85 millimeters wide) and large (0.85 to 2 millimeters wide) particles. In an initial test, the particles were added to either water or a buffer solution that mimicked soil conditions. They found that each nutrient released from both sizes of glass particles and diffused into the solutions steadily over 100 hours with minor fluctuations.
They then applied a nutrient solution or different amounts of the glass beads to soil seeded with a typical lawn and fairway grass, and they compared the plants’ growth in the two treatments. The nutrient solution, which was applied only once, immediately stimulated plant growth, but the effect quickly diminished. However, the single application of glass fertilizer sustained plant growth regardless of particle size, though overall growth depended on the bead dose.
Manzani and his colleagues also examined the possible environmental toxicity of the glass fertilizer by exposing lettuce and onion seeds to the beads. Seeds exposed to glass fertilizer had roughly the same germination rate and cell health as those never exposed or those treated with soluble nutrients. The researchers say that these results indicate an efficient and sustained alternative to conventional fertilizers with lower environmental impact.
The researchers also note that the beads may help aerate plant roots. The scientists were inspired by a previous study, in which particles of recycled bottle glass were shown to help oxygenate plants’ roots while maintaining optimal moisture levels. The full study is available HERE.
