Temporal Effects of the Combined Use of Cricket Frass and Eucalyptus Biochar on the Yield and Tissue Nitrate Content in Chinese Kale

Abstract

A greenhouse experiment was conducted to estimate the influence of various application rates of eucalyptus-derived biochar combined with cricket frass on the soil properties and soil N transformation, and, in turn, affecting both shoot biomass yield and nitrate (NO3-) contents of Chinese kale (Brassica oleracea). Two consecutive kale crops were grown to investigate the temporal effect of the combined amendments of cricket frass and biochar. Six rates of biochar, 0%, 0.125%, 0.25%, 0.5%, 1%, and 2% w/w in combination with 0.55% w/w of cricket frass, were applied only once at the start of the experiment in sandy loam soil. Shoot biomass significantly increased under treatments of 0.125% to 0.5% w/w in the first kale crop and 0.125% to 0.25% w/w in the second crop compared to the cricket frass alone. However, the higher rates of 0.25% and 0.5% w/w within the first and second crops decreased shoot biomass relative to their lower rates in each crop. Tissue NO3- concentrations of the first kale crop significantly decreased under all biochar rates, whereas the opposite effect was observed in the second crop. These contrasting effects of biochar on tissue NO3- concentrations were attributed to nitrification inhibition in the first crop and nitrification stimulation in the second crop. The 0.125% w/w rate of eucalyptus-derived biochar was, therefore, recommended to be combined with cricket frass to improve yield and reduce tissue NO3- content in the production of Chinese kale.

Effect of Cricket Frass Fertilizer on growth and pod production of green beans (Phaseolus vulgaris L.)

“…Unlike the frass of mealworms (Tenebrio molitor L.) and black soldier flies (Hermetia illucens L.), which have been the object of more numerous studies referring to their fertilizing potential, few studies have explored the use of cricket frass to amend soils for crops [22][23][24]. Butnan et al (2022) showed that combining cricket frass with Eucalyptus biochar improved the yield of Chinese kale (Brassica oleracea L.).…”

“…Unlike the frass of mealworms (Tenebrio molitor L.) and black soldier flies (Hermetia illucens L.), which have been the object of more numerous studies referring to their fertilizing potential, few studies have explored the use of cricket frass to amend soils for crops [22][23][24]. Butnan et al (2022) showed that combining cricket frass with Eucalyptus biochar improved the yield of Chinese kale (Brassica oleracea L.). An experiment comparing the growth of spider plant (Cleome gynandra L.) supplemented with cricket frass, cow manure, and synthetic fertilizer showed that frass increased available nitrogen in the soil, and improved vegetative growth [24].…”