The Effects of Insect Frass Fertilizer and Biochar on the Shoot Growth of Chicory and Plantain, Two Forage Herbs Commonly Used in Multispecies Swards

Abstract

Livestock farmers are seeking ways to lower their environmental footprints by reducing inputs, lowering greenhouse gas emissions, and enhancing carbon sequestration. To meet these objectives, farmers are investigating the value of diverse multispecies grazing swards and various organic by-products as alternative fertilizers and soil amendments. This study investigated the effects of HexaFrass™ [HexaFly, Meath, Ireland], an insect frass based organic fertilizer, and biochar, a form of charcoal, on the shoot dry matter accumulation of two forage plants, chicory and ribwort plantain. Under glasshouse conditions, HexaFrass™ generally increased the shoot growth of both chicory and plantain, although these positive effects were lost if an excessive amount of HexaFrass™ was applied, or the growing medium was already nutrient-rich. Importantly, it was found that HexaFrass™ also increased the re-growth of shoots after cutting, which is vital for plants that are destined to be successfully used in grazing or silage swards. Biochar had a less obvious effect on the shoot dry matter accumulation, although there was some evidence of a synergy between biochar and HexaFrass™, which caused an additional increase in the shoot growth. The results indicate that frass-based fertilizers could play a role in low-input mixed swards, whereas the potential of biochar as a soil amendment in these grazing systems requires further research.