Improvement on soil structure and water retention after application of industrial organic waste as a crop fertilizer

Purpose Industrial organic waste (IOW) from slaughter and processing of poultry and swine might be potential crop fertilizer. The use of IOW is known to alter the dynamics of soil organic carbon (SOC) and exchangeable cations. However, its effects on soil physical properties and processes are still unknown. The aim of this study was to evaluate the effects of the isolated and combined application of IOW and mineral fertilizers (MF) on SOC pools, structural physical properties, water retention, and some chemical properties under long-term no-tillage system. Materials and methods Treatments applied during 6 years were as follows: control (no fertilizers application) and crop nutrients through MF, IOW, and MF + IOW. We evaluated SOC pools (total, permanganate (POx-C), and hot water extractable (HWE-C)), structural soil physical properties (i.e., porosity and water retention), and exchangeable cation contents at 0-10 and 10-20 cm layers. Results and discussion The HWE-C increased in response to IOW application in relation to the control treatment at the 0-10 cm layer. POx-C with MF was closer to IOW application. However, this SOC pool was more affected at 10-20 cm layer, in which the IOW and MF promoted increases of POx-C in relation to control. Both forms of fertilization increased total porosity and water retention and the highest values were observed for IOW. We observed a high correlation between the increases of labile SOC and the improvement of soil physical conditions. The long-term exclusive MF application induced damages on soil, such as decreases in water retention and availability of nutrients. The results of MF + IOW were closer to those of MF treatment than IOW treatment. Conclusions The IOW evaluated is a suitable fertilization strategy, providing soil quality. But their use must be carried out in isolation or in combinations with mineral fertilizers greater than 50% of the blend. Also, this IOW is harmless to health and hygiene due to its treatment.