Fuentes alternativas de fósforo en sistemas agrícolas: Respuesta agronómica de un cultivo de maíz y salidas de nutrientes del sistema

This work explores the use of alternative sources of phosphorus, such as pulp industry sludge, manure and hot bedding from a confined dairy farm, as an alternative to inorganic fertilizers in maize (Zea mays) production. The research addresses the need to know the impact on agricultural production of replacing inorganic fertilizers with alternative sources of phosphorus, which represent an opportunity to reuse existing residues. In addition, their use could reduce dependence on chemical inputs, promote a circular economy by valorizing these wastes, and contribute to mitigating the associated environmental impacts. The main objective was to evaluate the potential of these organic amendments to maintain maize yields and improve soil nutrient availability, focusing on phosphorus. In addition, the impact of these amendments on phosphorus and sediment export in surface runoff was analyzed because of its relevance to environmental impact. During the 2023/2024 summer harvest, a trial was conducted in a randomized complete block experimental design with eight treatments and three replications, including paired controls to correct for variations in field conditions. Variables analyzed included grain yield, accumulated aerial biomass, soil, plant, and grain phosphorus concentrations, and phosphorus losses in surface runoff and sediment runoff. The treatments included amendments applied at equal doses of phosphorus and, in the case of sludge, at double doses. The results indicated that on soils with high initial phosphorus levels, the application of organic amendments had a limited effect on biomass and grain yield. At the same time, phosphorus stratification was evident in the topsoil layer (0-2.5 cm), which increases the risk of surface runoff losses. While no notable discrepancies were identified in phosphorus concentrations in runoff water, the treatments with sludge and hot bed exhibited elevated values, suggesting a heightened susceptibility to contamination. Conversely, the concentration of sediment in the runoff water did not demonstrate substantial variations between treatments. However, both phosphorus and sediment concentrations in runoff water exhibited notable fluctuations between precipitation events, influenced by the crop's phenological stages and the volume of precipitation.