Department of Chemistry, Federal University of São Carlos, Washington Luiz Highway, km 235, São Carlos, SP, 13565-905, Brazil.
Embrapa Instrumentation, XV de Novembro Street, n 1452, São Carlos, SP, 13560-970, Brazil.
Sci Rep. 2022 Aug 19;12(1):14176. doi: 10.1038/s41598-022-18214-8.
Struvite (St) recovered from wastewaters is a sustainable option for phosphorus (P) recovery and fertilization, whose solubility is low in water and high in environments characterized by a low pH, such as acidic soils. To broaden the use of struvite in the field, its application as granules is recommended, and thus the way of application should be optimized to control the solubility. In this study struvite slow-release fertilizers were designed by dispersing St particles (25, 50, and 75 wt%) in a biodegradable and hydrophilic matrix of thermoplastic starch (TPS). It was shown that, in citric acid solution (pH = 2), TPS promoted a steadier P-release from St compared to the pure St pattern. In a pH neutral sand, P-diffusion from St-TPS fertilizers was slower than from the positive control of triple superphosphate (TSP). Nevertheless, St-TPS featured comparable maize growth (i.e. plant height, leaf area, and biomass) and similar available P as TSP in sand after 42 days of cultivation. These results indicated that St-TPS slow P release could provide enough P for maize in sand, achieving a desirable agronomic efficiency while also reducing P runoff losses in highly permeable soils.
从废水中回收的鸟粪石（St）是回收磷（P）和施肥的可持续选择，其在水中的溶解度较低，在 pH 值较低的环境（如酸性土壤）中则较高。为了拓宽鸟粪石在实际中的应用，推荐将其制成颗粒状，因此需要优化其应用方式以控制其溶解度。在本研究中，通过将 St 颗粒（25、50 和 75wt%）分散在可生物降解和亲水性的热塑性淀粉（TPS）基质中，设计了鸟粪石缓释肥料。结果表明，在柠檬酸溶液（pH=2）中，与纯 St 模式相比，TPS 可使 P 从 St 中的释放更稳定。在中性 pH 值的沙中，St-TPS 肥料中 P 的扩散速度比三料过磷酸钙（TSP）的阳性对照要慢。然而，在 42 天的培养后，St-TPS 在沙中对玉米的生长（即株高、叶面积和生物量）和有效 P 的效果与 TSP 相当。这些结果表明，St-TPS 缓慢释放 P 可在沙中为玉米提供足够的 P，在高度渗透的土壤中可实现理想的农业效率，同时减少 P 径流损失。
