UC Riverside

The health of turfgrass, as well as the quality of managed turfgrass areas, relies heavily on the amount of irrigation which can be supplied to plants. As restrictions require that irrigation rates be reduced, many professionals turn to organically derived soil amendments with the potential for reducing irrigation requirements. Compost is a stabilized form of organic matter derived from the biological decomposition of plant, animal, or human waste, and is often used for soil fertilization and amelioration. Biochar is produced through anaerobic heating of plant biomass to produce extremely stable carbon in the form of amorphous graphene sheets. Both technologies increase soil organic matter (SOM), which can convey improvements in soil water retention and Cation Exchange Capacity (CEC). Biochar may also positively impact soil structure, increasing porosity and reducing density in a way which improves root penetration and water infiltration. Biochar is more highly resistant than compost to degradation and recent work has suggested a synergistic effect between biochar and compost materials. Multiple studies were conducted at University of California Riverside from 2014 to 2017 in field and greenhouse conditions to evaluate the effects of compost, biochar, and combined biochar and compost amendments on the establishment and drought tolerance of tall fescue (Festuca arundinacea L.). Soil amendments designed for improvement of soil conditions during periods of drought are often evaluated in the lab using measurements of soil water potential. Results of these studies suggest that this measurement does not accurately gauge impacts on plant health. In both field and greenhouse studies, compost amendments significantly slowed establishment, while biochar did not affect establishment rates compared to controls. When subjected to drought, turf grown in soils amended with compost or biochar amendments were able to maintain higher visual quality with reduced supplemental irrigation. We conducted a series of experiments to analyze the effect of compost and biochar amendments during each stage of development of a healthy turf, allowing managers to more accurately predict the impacts of these products.