Department of Soil Science, Luiz de Queiroz College of Agriculture (Esalq), University of São Paulo (USP), Av. Pádua Dias, 11, 13418-900, Piracicaba, SP, Brazil.
Division 4.4 - Thermochemical Residues Treatment and Resource Recovery, German Federal Institute for Materials Research and Testing (BAM), Richard-Willstätter-Straße, 11, 12489, Berlin, Germany.
J Environ Manage. 2022 Jan 15;302(Pt A):113984. doi: 10.1016/j.jenvman.2021.113984. Epub 2021 Oct 23.
Conventional phosphate fertilizers are usually highly water-soluble and rapidly solubilize when moistened by the soil solution. However, if this solubilization is not in alignment with plants demand, P can react with the soil colloidal phase, becoming less available over time. This is more pronounced in acidic, oxidic tropical soils, with high P adsorption capacity, reducing the efficiency of P fertilization. Furthermore, these fertilizers are derived from phosphate rock, a non-renewable resource, generating an environmental impact. To assess these concerns, waste-recycled P sources (struvite, hazenite and AshDec®) were studied for their potential of reducing P fixation by the soil and improving the agronomic efficiency of the P fertilization. In our work, we compared the solubilization dynamics of struvite, hazenite, AshDec® to triple superphosphate (TSP) in a sandy clay loam Ferralsol, as well as their effect on solution pH and on soil P pools (labile, moderately-labile and non-labile) via an incubation experiment. Leaching columns containing 50 g of soil with surface application of 100 mg per column (mg col) of P from each selected fertilizer and one control (nil-P) were evaluated for 60 days. Daily leachate samples from the column were analyzed for P content and pH. Soil was stratified in the end and submitted to P fractionation. All results were analyzed considering p < 0.05. Our findings showed that TSP and struvite promoted an acid P release reaction (reaching pHs of 4.3 and 5.5 respectively), while AshDec® and hazenite reaction was alkaline (reaching pHs of 8.4 and 8.5 respectively). Furthermore, TSP promoted the highest P release among all sources in 60 days (52.8 mg col) and showed rapid release dynamic in the beginning, while struvite and hazenite showed late release dynamics and lower total leached P (29.7 and 15.5 mg col P respectively). In contrast, no P-release was detected in the leachate of the AshDec® over the whole trial period. Struvite promoted the highest soil labile P concentration (7938 mg kg), followed by hazenite (5877 mg kg) and AshDec® (4468 mg kg), all higher than TSP (3821 mg kg), while AshDec® showed high moderately-labile P (9214 mg kg), reaffirming its delayed release potential.
传统的磷酸盐肥料通常具有高水溶性，在被土壤溶液润湿时会迅速溶解。然而，如果这种溶解与植物的需求不匹配，磷就会与土壤胶体相反应，随着时间的推移变得越来越不活跃。在酸性、氧化的热带土壤中，这种情况更为明显，因为这些土壤具有高磷吸附能力，从而降低了磷肥的效率。此外，这些肥料来自不可再生资源磷矿，会产生环境影响。为了评估这些问题，研究了废物回收磷源（鸟粪石、磷钙石和 AshDec®）在减少土壤磷固定和提高磷肥农学效率方面的潜力。在我们的工作中，我们比较了鸟粪石、磷钙石、AshDec®在砂壤土 Ferralsol 中的溶解动力学与三料过磷酸钙（TSP）的差异，以及它们通过培养实验对溶液 pH 值和土壤磷库（活性、中度活性和非活性）的影响。通过表面应用每柱 100mg 磷（mg col）的每种选定肥料（TSP、鸟粪石、磷钙石、AshDec®）和一个对照（无磷），对含有 50g 土壤的淋滤柱进行了 60 天的评估。每天从柱中提取的淋出液样品进行磷含量和 pH 值分析。柱结束时分层土壤，并进行磷分级。所有结果均考虑到 p<0.05。我们的发现表明，TSP 和鸟粪石促进了酸性磷释放反应（分别达到 pH 值 4.3 和 5.5），而 AshDec®和磷钙石的反应呈碱性（分别达到 pH 值 8.4 和 8.5）。此外，在 60 天内，TSP 是所有来源中释放磷最多的（52.8mg col），在开始时释放迅速，而鸟粪石和磷钙石则在后期释放，总淋出磷较少（分别为 29.7 和 15.5mg col P）。相比之下，在整个试验期间，AshDec®淋出液中未检测到磷释放。鸟粪石促进了土壤中最高的活性磷浓度（7938mg kg），其次是磷钙石（5877mg kg）和 AshDec®（4468mg kg），均高于 TSP（3821mg kg），而 AshDec®表现出较高的中度活性磷（9214mg kg），证实了其延迟释放的潜力。
