Assessment of plant growth performance and nutrient release for application of phosphorus-loaded layered double hydroxides as fertilizer

Seed germination and early growth assays of lettuce (Lactuca sativa L.) were used as means in the evaluation of different dosage performances of P-loaded layered double hydroxides (P-LDHs). Of these two experiments, results from the former showed that PLDH application at lower concentrations (0.5 and 1.0 g) influenced the slightly delayed germination, which decreased by no more than approximately 12% compared to that of untreated seeds, whereas the total germination failure was observed once seeds were established with higher ones (2.5 and 5.0 g) because of Al toxicity. Statistical analysis also revealed that a significant dose-dependent inhibition of seed germination was attained after P-LDH administration of at least 1.0 g. On the contrary, beneficial effects were obtained in the successive experiments, where P-LDHs at 0.5, 1.0, 2.5, and 5.0% (w/w) were applied to the growing media. P-LDHs applied at 1.0% outperformed other treatments as well as the control in stimulating plant improvement. The length of lettuce shoots and roots was improved by at least 6.75% compared to those of the non-treated samples and by 10.80% to 30.83% compared with other application rates. The greatest biomass accumulation (1.723 g) was also found in lettuce supplemented with 1.0% of P-LDHs, whereas those without P-LDHs reached their lowest fresh weight (1.422 g). In this experiment, an inadequate supply of Mg could be detrimental to plants from the last two treatment groups. In addition, findings of nutrient leaching verified that P stored in these products was released slowly, and thus they were able to deliver this essential nutrient to plants gradually over a longer period. In summary, this study pointed out that post-adsorption LDHs did not have the ability to boost seed germination, regardless, they could be reused as an agricultural fertilizer to encourage crop quality cultivated under substrate or soil conditions, where an application rate of 1.0% (w/w) was recommended in order to avoid the exposure of excess nutrient levels to the targeted plants. (C) 2021 Elsevier B.V. All rights reserved.