Application of a glass fertilizer in sustainable tomato plant crops

Abstract

BACKGROUND: Glass frits with a P2O5/K2O ratio equal to 0.65 and different concentrations of SiO2 (6.5–56.0 wt%), CaO (0–5.1 wt%) and Al2O3 (0–14.6 wt%) have been prepared and analysed as potential glass fertilizers (GF). RESULTS: P2O5 and K2O were leached primarily within the first 5 days but the total amount was dependent on the SiO2/Al2O3 ratio of the glass frit. Sustained P2O5 and K2O leaching for more than 40 days could be obtained if the glass frit contained more than 7% Al2O3. A final glass frit composition (29% SiO2, 5% CaO, 7% Al2O3, 30% P2O5, 25% K2O) was selected and used in an experimental tomato crop of 1 ha area, where one half was fertilized with an NPK conventional fertilizer and the other half with the GF fertilizer. CONCLUSION: After harvesting the tomato crops, the GF fertilizer was found to result in a higher yield than the NPK conventional fertilizer: 59980 kg and 74 360 kg for NKP and GF, respectively. The general characteristics of the harvested tomato fruits and leaves were similar in the two cases and the differences fell within statistical error. No differences in any of the soil characteristics were detected as a result of the use of GF. © 2018 Society of Chemical Industry.