The Response of Monoecious and Dioecious Cultivars of Agricultural Hemp to an Organic Fertiliser Derived from Black Soldier Fly Frass.

Abstract

The development of sustainable food systems requires the appraisal of novel methods of maintaining soil nutrients and the evaluation of alternative crops and sward systems. Accordingly, this study examined how agricultural hemp responded to an organic fertiliser produced from black soldier fly (BSF; Hermetia illucens) frass. The results indicate that at equivalent N-rates (approx. 0.16 g N per pot), a commercial BSF frass fertiliser ("HexaFrass") produced similar increases in shoot growth of monoecious and dioecious hemp seedlings as was achieved with established organic fertilisers (chicken manure; Miracle-gro). In one cultivar, CFX-2, it was shown that positive effects on shoot growth could be achieved at low fertiliser rates (≤4 g per pot), and additional fertiliser dd not induce additional shoot growth. Application of HexaFrass increased the shoot content of P, K, and Mg but not N, an important consideration if hemp straw and foliage are to be used as livestock feed. Insect frass fertilisers can supply hemp seedlings with the nutrients required for accelerated shoot growth, but further work is needed to evaluate different fertiliser regimes (e.g., split application; liquid extracts) and to assess how frass fertilisers affect yield and chemical profiles of hemp seeds.