Sources and methods of phosphorus application in maize cultivation

Despite having a vast area for agricultural production, Brazil is highly dependent on mineral sources forphosphate fertilisers, making their use unsustainable and highly dependent on the international market. The aim of the presentstudy was to evaluate the effect of different sources of phosphate fertiliser and the depth of application on the development andproductivity of maize over two crop seasons. A randomised block design was used in a 3 x 4 factorial scheme comprising 12 treatments,with four replications. Three sources of phosphorus were tested: single superphosphate (SSP), Top-Phos® (TOP-PHOS) andreactive natural phosphate (RNP), in addition to four methods of application (broadcast application [0.00 m] and in-furrowapplication at three depths [0.05 m, 0.08 m and 0.11 m]). The following parameters were evaluated: final plant stand, plantheight, stalk diameter, ear insertion height, number of rows per ear, number of grains per row, 1000-grain weight, and grainproductivity. The data were submitted to analysis of variance using the F-test at a level of 5%, and to principal componentanalysis (PCA) with biplot graphical analysis. The use of SSP and Top-Phos® increased productivity and the ear insertionheight compared to the use of RNP. Applications made at a depth of 0.11 m were the most efficient. Seasonal variables affectedproductivity, with Top-Phos® showing a greater correlation with the yield metrics at greater depths.