Rev. Bras. Ciênc. Solo.2025;49(spe1):e0240124.

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Sewage sludge-based organomineral fertilizer improves phosphorus efficiency in Urochloa brizantha

Andre Luiz de Freitas Espinoza , João Henrique Silva da Luz , Tiago Tezotto , Paulo Sergio Pavinato

17/jun/2025

DOI: 10.36783/18069657rbcs20240124

Resumo Gráfico

ABSTRACT

Sewage sludge (SS) from wastewater treatment has reasonable phosphorus (P) levels, which could be used as fertilizer in agriculture. However, SS-P content is lower than mineral fertilizers, which limits its operational application. The blend of organic and mineral material can increase the P content, formulating organomineral fertilizers (OMF) with higher P levels, enabling agricultural use. This study aimed to assess the agronomic efficiency and residual effect of organomineral fertilizers derived from SS as phosphorus sources for Urochloa brizantha. A greenhouse pot experiment was conducted to evaluate the successive cultivation of U. brizantha over eight cycles, with the following treatments: SS organic compost (SSC) powder; SSC pelletized (SSP), SSC+MAP pelletized (S+MAP) and SSC+AshDec^® pelletized (S+ASD); AshDec^® powder (ASD), monoammonium phosphate (MAP) and a control (no P). In each Urochloa cycle, height, tillering, shoot dry mass (SDM), and leaf P were evaluated. After eight cycles, the soil was subjected to P fractional analysis. Our results showed that tillering was higher in all treatments with P compared to control (No P). Shoot dry mass production in the first cycle was higher with S+MAP (21.8 g pot^-1) than MAP (17.5 g pot^-1), and after eight cycles, the accumulated SDM of all treatments (>140 g pot^-1) was superior to MAP (132 g pot^-1), except for S+ASD (118 g pot^-1). No significant difference in plant height was observed. Total P uptake was higher in the treatments with recycled sources, however, plants fertilized with S+MAP accumulated more P during establishment, while SSC, SSP, and ASD promoted higher accumulation during 4 to 6 cycles. After eight cycles, soil labile P content was higher in treatments with OMFs compared to mineral sources, indicating a residual effect of organomineral fertilization. These results showed that SSC-derived OMFs are more efficient than conventional fertilizers if mixed with soluble mineral sources (MAP), but the same is not true with insoluble sources (ASD). Organomineral S+MAP can replace MAP, providing greater efficiency in forage establishment and a greater residual effect.