Abstract

Phosphorus (P) deficiency limits agricultural production in tropical and subtropical soils, where soil mineralogy is dominated by kaolinite, iron, and aluminum oxides. The aim of this work was to compare two application methods of P, to the soil surface and to the sowing line, to determine the most effective strategy to increase wheat and soybean yields on an oxidic subtropical soil in Brazil under field conditions. Additionally, four inorganic P fertilizers (monoammonium phosphate (MAP); single superphosphate (SS); triple superphosphate (TP); and natural rock phosphate (NP)) in a wheat crop and four different P rates (zero, 0; low, 45; medium, 90; and high, 180 kg ha⁻¹ of P₂O₅) of TP in a soybean crop were tested after being applied to the soil surface and to the sowing line. A significant increase in yield (54%) was only found when TP was applied to the sowing line in comparison with the soil surface in wheat plants, probably due to its high solubility. However, the application method did not produce a significant effect in soybean yields, probably because this crop has a different P requirement and root distribution pattern than wheat. In the case of P fertilizers applied to the soil surface, higher wheat yields were observed with NP and MAP in comparison with TP. Finally, a linear increase was observed in soybean yields while increasing the P rate, finding significant differences between the plants fertilized with the highest P rate and the non-P-fertilized plants (24% yield increase in the first case). Our results highlight the need for specific P fertilization strategies for the different crops grown on subtropical regions where soil mineralogy curbs P availability.

中文翻译：

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通过有效的磷肥策略提高亚热带土壤中小麦和大豆的产量

摘要

磷（P）的缺乏限制了热带和亚热带土壤的农业生产，那里的土壤矿物学以高岭石，铁和氧化铝为主。这项工作的目的是比较两种磷在土壤表面和播种上的施用方法，以确定在田间条件下提高巴西亚热带氧化性土壤上小麦和大豆产量的最有效策略。此外，小麦作物中还施用了四种无机磷肥（磷酸一铵（MAP），一种过磷酸钙（SS），三种过磷酸钙（TP）和天然岩磷（NP））和四种不同的磷素施用率（零，0，低，45）。 ；中等（90）和高（180 kg ha ^-1）的P ₂ O ₅将大豆作物中的TP施用到土壤表面和播种线上后进行测试。与小麦的土壤表面相比，仅将TP施用到播种行上时，才发现单产显着提高（54％），这可能是由于其高溶解度。但是，施用方法并未对大豆产量产生显着影响，可能是因为该作物的磷需求量和根系分配方式与小麦不同。在将磷肥施用到土壤表面的情况下，与TP相比，NP和MAP的小麦单产更高。最后，观察到大豆产量线性增加，同时增加了磷的施用率，发现最高磷施用量的植物与非磷施肥的植物之间存在显着差异（第一种情况下增加了24％）。