Soil Chemical Alteration Due to Treated Swine Wastewater Application in a Semi-arid Area in Southeastern Brazil

Using treated swine wastewater (TWW) for crop irrigation, especially in semi-arid regions, can help mitigate water demand–supply imbalances and prevent environmental degradation. Therefore, this study aimed to assess the impact of treated swine wastewater (TWW) application on soil fertility attributes and to establish management zones (MZs) for its optimal use.

Soil samples were collected using a regular grid of 110 points (10 × 10 m) across 1.25 ha, where annual applications of 500 m³ ha^–1 year^–1 of swine TWW were carried out for two years. The soil attributes evaluated included pH, soil organic matter (SOM), phosphorus (P), potassium (K), sodium (Na), calcium (Ca), magnesium (Mg), potential acidity (H + Al), sum of bases (SB), and potential cation exchange capacity (CEC).

The application of TWW significantly reduced soil pH and P levels while increasing SOM, K, Ca, SB, and CEC. However, the spatial variability maps of the soil attributes indicated low uniformity in the swine TWW application, demonstrating improper management of the irrigation system. Additionally, heterogeneity was observed for K, Na, Mg, and H + Al between the MZs.

The study identified two MZs, which served as a foundation for guiding the application of swine TWW and effectively managing soil fertility in the area.