Agronomic Effectiveness of Calcined Soluble Sources of P Fertilizers

Every winter fire strikes out in the Cerrado of Brazil due to climatic conditions of very low air humidity with high temperature burning natural vegetation or harvest residue on fields, and as growers apply fertilizers during winter, it may happen that broadcast fertilizers are affect by fire. Previous tests show decrease in P solubility of P fertilizers burned after field fire and no agronomic information is available under such conditions. Therefore, this project is aimed to investigate the effect of calcination on the solubility of soluble P fertilizers and on biomass yield of plants grown under greenhouse conditions.

IPNI-2014-BRA-65

29 Apr 2016

2015 Annual Interpretive Summary


Every winter, fire strikes the Cerrado region due to severe drought and high temperatures. Under such conditions (temperatures around 100°F and air humidity around 10%) fire becomes a major problem for natural reservation areas as well as for agricultural fields. As no-tillage has been greatly adopted by farmers, the crop residue on the soil has became a high potential fire risk and fires have occurred in many farm fields across the Mato Grosso. A previous and simple test has shown that superphosphates (TSP and SSP) that were surface applied on fields that subsequently caught fire presented some variation in water solubility (e.g., TSP control (43% P2O5 water soluble) versus burned TSP (12% P2O5 water soluble). This project aimed to evaluate agronomic effectiveness of different P fertilizers (TSP and SSP) in response to thermal treatments: (two times (5 or 20 minutes) and three temperatures (150, 300 and 400°C). A greenhouse trial is being carried out with soybean and maize to measure dry matter yield of shoots, P uptake, and soil P availability.

Results have shown a significant effect of thermal treatment of P fertilizers on dry matter yield of shoots and P uptake of soybean and maize, as well to extractable soil P concentrations. Expectantly, results have shown no significant effect of thermal treatment of P fertilizers (SSP and STP) on dry matter yield of shoots and P uptake of soybean and maize, as well as on soil P level, as compared to control (uncalcined P fertilizers). Regarding the conditions of this study, calcined SSP and STP are still sutaible as P sources to supply P to plants.