Dataset and Analysis Code for an Experiment on Phosphorus Fertilizers

https://github.com/jmalonso55/fosfatos

This repository includes the R script and a subset of the data from a manuscript currently under review, focused on the characterization and agronomic efficiency of natural and recovered phosphates in tropical soil with corrected acidity for maize cultivation. The study is part of the Master’s Dissertation of Ramos, J.F.K. (Ramos, J.F.K. 2023. Caracterização química, mineralógica e eficiência agronômica de diferentes fosfatos [Dissertation]. Universidade Federal Rural do Rio de Janeiro, Seropédica, Brasil).  Available in: https://rima.ufrrj.br/jspui/handle/20.500.14407/18645.

This study examined eleven phosphate fertilizer samples, encompassing Brazilian and imported products, as well as residue-recovered and soluble phosphates. The phosphate rocks of igneous origin were exclusively sourced from Brazil, specifically Catalão (Goiás) and Registro (São Paulo). Sedimentary sources included samples from Brazil (Arraias in Tocantins, Bonito in Mato Grosso do Sul, and Pratápolis in Minas Gerais) and from Morocco, Algeria, and Peru (Bayóvar). These phosphates are referred to as Catalão, Registro, Arraias, Bonito, Pratápolis, Morocco, Algeria, and Bayóvar, respectively.

The experiment was carried out in a greenhouse, using plastic pots as experimental units, each containing 2 kg of a Ferralsol sample. The soil, initially identified as acidic (pH 4.68), was subjected to a correction process prior to the experiment. The study employed a completely randomized design with 12 treatments and four replicates, resulting in a total of 48 experimental units. The treatments included phosphate rocks (Catalão, Registro, Bonito, Pratápolis, Arraias, Morocco, Algeria, and Bayóvar), two animal-origin phosphates (Bonechar and ERCP), triple superphosphate (TSP) as a reference, and a control treatment without a phosphorus source.

Each treatment received a single application of 320 mg P per pot (equivalent to 160 mg P per kg of soil), which was thoroughly incorporated into the soil before planting. The experiment spanned two successive cropping cycles, each lasting 45 days. At the end of each cycle, the aboveground parts of the plants were harvested, dried in a forced-air oven at 65°C until a constant weight was achieved, and their shoot dry mass (SDM) was recorded. The dried samples were finely ground in a Wiley mill and further processed in a ball mill for phosphorus content analysis. To evaluate the agronomic efficiency of the phosphate sources, the study calculated the Relative Agronomic Efficiency Index (RAE) and Phosphorus Efficiency (PE).