Soluble phosphates are the most common sources currently used in crop production in tropical soils; however, they present low efficiency and are more expensive than natural rock phosphates. The objective was to develop new phosphate fertilizers with slow solubility through the partial acidification of rock phosphates (RPs), incorporating materials with adsorption characteristics to favor slow dissolution and prevent phosphorus (P) fixation in the soil. Three rock phosphates, Araxá (ARP), Bayovar (BRP) and Morocco (MRP), were evaluated at two acidulation levels (25 and 50% Ac.) and two additives; pillared clays (PILC) and zeolites (Zeo), plus triple superphosphate (TSP) and a control (nil-P). The soil diffusion was evaluated in concentric rings in Petri dishes. Solubility was evaluated in leaching columns and sampled in layers from surface for P forms in the soil profile. The relative agronomic efficiency (RAE) was evaluated in maize. Greater diffusion was provided by TSP, followed by BRP and MRP both with 50% Ac. + Zeo, and MRP with 50% Ac. + PILC. Percolated P was more pronounced under TSP, followed by RPs (BRP and MRP) with 50% Ac. + Zeo. BRP and MRP + 50% Ac. were the most promising sources with RAE above 74% compared to TSP.

中文翻译：

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沸石和柱撑粘土作为添加剂部分酸化的磷矿石肥料的溶解度和效率

易溶 磷酸盐是目前热带土壤中作物生产中最常用的来源；但是，它们的效率低下，并且比天然磷酸盐更昂贵。目的是通过对岩石磷酸盐（RPs）的部分酸化，开发具有低溶解度的新型磷酸盐肥料，并结合具有吸附特性的材料来促进缓慢溶解并防止磷（P）固定在土壤中。在两种酸化水平（25％和50％Ac。）和两种添加剂下评估了三种磷酸盐岩，即Araxá（ARP），Bayovar（BRP）和摩洛哥（MRP）。柱状粘土（PILC）和沸石（Zeo），以及三重过磷酸钙（TSP）和对照（nil-P）。在培养皿中的同心环中评估土壤的扩散。在浸出柱中评估溶解度，并从表面分层取样以获取土壤剖面中的P形式。在玉米中评估了相对农艺效率（RAE）。TSP提供了更大的扩散，其次是BRP和MRP都含有50％的Ac。+ Zeo和含50％Ac的MRP。+ PILC。在TSP下，渗透的P更为明显，其次是RP（BRP和MRP）和50％Ac。+ Zeo。BRP和MRP + 50％Ac。与TSP相比，RAE高于74％是最有希望的来源。