Uso de cama de aviário como estratégia de mitigação da dependência de fertilizantes minerais: impacto no rendimento de grãos e na fertilidade do solo

Abstract

Brazil stands out as one of the world's leading grain producers, yet it faces the challenge of high dependence on chemical fertilizers and the consequent increase in production costs. In this context, the utilization of agro-industrial residues, such as poultry litter, emerges as a technically, economically, and environmentally sustainable alternative, especially in the Southwest region of Paraná, due to its significant availability. This study aimed to evaluate the effects of continuous application of different poultry litter treatments and mineral fertilization on the agronomic performance of soybean (Glycine max) and maize (Zea mays) crops, as well as on the dynamics of soil chemical attributes in a long-term succession system initiated in 2012 in Dois Vizinhos, PR. The experiment was conducted in a randomized block design with 10 treatments and 3 replications. Increasing doses of poultry litter (0, 3, 6, and 9 t ha⁻¹) and the association of a fixed dose (6 t ha⁻¹) with different levels of top-dressed nitrogen (0, 75, 150, and 225 kg ha⁻¹) were evaluated. Additionally, a control treatment with recommended mineral fertilization (MF) was included. The total accumulated yield over all harvests differed statistically among treatments. The lowest accumulated production was obtained in the absence of fertilization, with 61,374 kg ha⁻¹. The highest accumulations were achieved with poultry litter doses of 9 and 6 t ha⁻¹, with 106,561 and 95,998 kg ha⁻¹, respectively, being statistically equivalent to each other and to mineral fertilization (AM), which totaled 101,052 kg ha⁻¹. Notably, the 9 t ha⁻¹ dose numerically surpassed AM by 5.5%. These results demonstrate that the application of poultry litter from 6 t ha⁻¹ onwards is capable of fully replacing mineral fertilization without compromising total yield in the soybean-maize rotation system over more than a decade of cultivation. In addition to productive gains, the results indicated that poultry litter application promoted significant improvements in soil fertility, maintaining pH within ideal ranges, raising base saturation to levels close to 70%, and reducing exchangeable aluminum toxicity. Furthermore, an increase in calcium, magnesium, phosphorus, and potassium contents proportional to the increase in applied doses was observed, highlighting the high residual effect of the organic input. It is concluded that poultry litter is capable of fully supplying the nutritional demands of the soybean-maize system and improving soil chemical properties in the long term, consolidating itself as an effective strategy for mitigating dependence on mineral fertilizers and promoting sustainability in the agroecosystem. However, it is important to note that the dose of organic residue as a source of phosphorus and potassium, and as a source of nitrogen for maize in the short term, may result in the accumulation of P and K in the soil, which could lead to environmental problems.