Growth response of barley to short-term combined application of sewage sludge and conventional fertilizer

Aim of study: Agricultural nitrogen (N) losses from synthetic fertilizer significantly impact soil-plant-water system. The use of sewage sludge (SS) as a fertilizer presents a cost-effective and sustainable alternative, aiming to reduce dependence on chemical fertilizers, while boosting crop productivity. Area of study: The research was conducted at the National Research Institute of Rural Engineering, Water and Forests, Tunisia. Material and methods: A greenhouse experiment was conducted in rhizotrons to assess the impact of SS applied alone (T3: 100% N SS) or combined with three levels of mineral fertilizer (MF) (T4: 30% N MF + 70 % N SS, T5: 50 % N MF + 50 % N SS, and T6: 70% N MF + 30% N SS) on barley (Hordeum vulgare L.) growth and production, compared with the sole application of MF (T2), and an unfertilized control (T1). Main results: SS, whether applied alone or in combination with MF, significantly promoted tillering and shoot growth compared to control and chemically amended plants. The increases in the tiller number reached 90% and 56% in T4, compared to T1 and T2, respectively. Biomass production was also highest in SS treatments. The greatest above-ground biomass accumulation occurred in T4 and T3, with increases of 119% and 78% over T1 and T2, respectively. Research highlights: When applied in strict compliance with regulatory standards, SS demonstrates significant agronomic value by improving forage biomass yield and productivity at a lower cost, while reducing reliance on synthetic fertilizers.