Biosolids and biochar application effects on bahiagrass herbage accumulation and nutritive value

Abstract

AbstractPastures represent the major cropping system where biosolids are recycled in Florida, yet limited information is available documenting the agronomic benefits of biosolids recycling programs. A 2‐yr experiment evaluated bahiagrass (Paspalum notatum Flügge) responses to application of biosolids and inorganic fertilizer applied either alone or in combination with biochar. Our hypothesis was that biochar could alter soil N and P dynamics, thus, affecting crop nutrient use efficiency. Treatments were a factorial arrangement of four fertilizer sources (inorganic fertilizer, thermally dried Class AA biosolids, aerobically digested Class B biosolids, and anaerobically digested Class B biosolids; surface‐applied at 160 kg plant available N ha−1 yr−1) with or without biochar (applied at 1% wt basis). Bahiagrass total annual herbage accumulation was similar for biosolids and inorganic fertilizer treatments in 2017; however, inorganic fertilizer and aerobically digested Class B biosolids increased total annual herbage accumulation by as much as ∼29% relative to other sources in 2018. Biosolids and inorganic fertilizer increased bahiagrass crude protein (CP) concentration by as much as ∼22 and ∼39% in 2017 and 2018, respectively, compared to unfertilized treatment. No treatment effects were observed on in vitro digestible organic matter (IVDOM) concentration in 2017; however, in 2018 biosolids resulted in greater IVDOM than inorganic fertilizer. Data suggested no benefit of biochar on bahiagrass responses. Bahiagrass tissue mineral concentrations in both biosolids and inorganic fertilizer treatments were generally within sufficient range for optimum plant growth. Biosolids can be a viable alternative for sustainable bahiagrass production while reducing the dependence on inorganic fertilizer.