Abattoir Wastewater Irrigation Increases the Availability of Nutrients and Influences on Plant Growth and Development

This study evaluated the effects of abattoir wastewater irrigation on plant growth and development. The soils used in this study were collected from Primo Smallgoods Abattoir (Port Wakefield, South Australia) at different sites such as currently irrigated (CI), currently not irrigated (CNI) and soil outside the irrigation area as control (CTRL). A completely randomised block design was employed for the plant growth experiment, where four crops (Pennisetum purpureum, Medicago sativa, Sinapis alba and Helianthus annuus) were grown separately on three different soils (CI, CNI and CTRL) in plastic pots. Two types of water (tap water and wastewater) and two loadings were applied throughout the planting period based on the field capacity (FC 100 and 150 %). The overall dry matter yield was compared between the soils and treatments. Under wastewater irrigation, among the four species grown in the CI soil, P. purpureum (171 g) and H. annuus (151 g) showed high biomass yields, followed by S. alba (115 g) and M. sativa (31 g). The plants grown under tap water showed about 70 % lower yields compared to the abattoir wastewater irrigation (AWW). Similar trends in the biomass yields were observed for CNI and CTRL soils under the two water treatments, with the biomass yields in the following order CI > CNI > CTRL soils. The results confirm the beneficial effects of AWW at the greenhouse level. However, a proper cropping pattern and wastewater irrigation management plan is essential to utilise the nutrients available in the wastewater-irrigated land treatment sites. The increase in fertility is evident from the effects of wastewater on biomass growth and also the abundance of nutrients accumulated in plants. A mass balance calculation on the applied, residual and the plant-accumulated nutrients over a few cropping periods will help us in understanding the nutrient cycling processes involved in the abattoir-irrigated land treatment sites, which will serve as an effective tool for the environmental management.