The commercial rearing of insects is a growing economic sector. Therefore, an assessment was made of the potential of its by-product, frass, to be a soil improver. Essential plant nutrients were extracted (using 0.01 M CaCl₂ or Mehlich 3) from frass of mealworms (Tenebrio molitor), black soldier flies (Hermetia illucens) and buffalo worms (Alphitobius diaperinus). A 28-day incubation, in which frass was added to a sandy loam soil at application rates of 2.5% or 5% (w/w), assessed its effects on soil microbial biomass, abundance of bacteria, archaea and fungi, carbon mineralisation and nitrification. In a separate 56-day incubation, the impact of frass on heavy metal bioavailability in an artificially contaminated, carbon-poor substrate was tested. All frass types featured high electrical conductivity, a mildly acidic to neutral pH and C: N ratios between 11 and 16. Black soldier fly frass (BSFF) was richer in extractable ammonium, phosphorus, potassium and magnesium than mealworm frass (MWF) and buffalo worm frass (BWF) but poorer in extractable calcium. All frass types stimulated carbon mineralisation, nitrification, bacterial and archaeal 16S rRNA gene copy numbers, and fungal biomass as determined by ergosterol concentrations. Bacterial and particularly fungal abundances were stimulated by the 5% frass application rate whereas archaeal abundances were greater in the 2.5% application rate regimes. The 2.5% application rate of MWF and BWF led to a profound build-up of soil extractable nitrite. Correspondingly, these treatments featured the highest 16S rRNA gene copy numbers of archaea, a domain encompassing organisms which oxidise ammonium to nitrite. No nitrite was detectable in soil amended with BSFF. The 5% application rates induced microbial biomass growth (as determined by extractable DNA concentrations) only when BSFF was applied. This was possibly due to differences in the frass types' extractable nutrient or labile carbon contents. BSFF and BWF amendment led to significantly higher microbial biomass in a metal-contaminated substrate. This was likely due to frass providing nutrients, energy and reduced metal bioavailability: extractable zinc, copper, cadmium and nickel concentrations fell due to increased metal sorption and complexation. All frass types could be used as ameliorants in metal-contaminated soils, while BSFF shows most promise as an organic fertiliser as its use did not cause soil nitrite build-up.

昆虫的商业饲养是一个不断增长的经济部门。因此，对其副产品碎屑作为土壤改良剂的潜力进行了评估。从黄粉虫 ( Tenebrio molitor )、黑水虻 ( Hermetia illucens ) 和水牛蠕虫 ( Alphitobius diaperinus )中提取植物必需营养素（使用 0.01 M CaCl ₂或 Mehlich 3））。在为期 28 天的孵化过程中，以 2.5% 或 5% (w/w) 的施用率向砂质壤土中添加碎屑，评估其对土壤微生物生物量、细菌丰度、古细菌和真菌、碳矿化和硝化作用。在单独的 56 天孵化中，测试了人工污染的、贫碳的底物对重金属生物利用度的影响。所有类型的草都具有高导电性、弱酸性到中性的 pH 值和 C:N 比率在 11 和 16 之间。 黑水虻 (BSFF) 比黄粉虫 (MWF) 和水牛富含可提取的铵、磷、钾和镁worm frass (BWF) 但可提取的钙较差。所有 frass 类型都刺激了碳矿化、硝化作用、细菌和古菌 16S rRNA 基因拷贝数、和真菌生物量，由麦角甾醇浓度确定。细菌和特别是真菌的丰度受到 5% 的 fras 施用率的刺激，而古菌丰度在 2.5% 的施用率方案中更高。MWF 和 BWF 的 2.5% 施用率导致土壤可提取亚硝酸盐的大量积累。相应地，这些处理具有古细菌最高的 16S rRNA 基因拷贝数，古细菌是一个包含将铵氧化为亚硝酸盐的生物的域。在用 BSFF 改良的土壤中未检测到亚硝酸盐。仅当应用 BSFF 时，5% 的施用率才会诱导微生物生物量增长（由可提取的 DNA 浓度确定）。这可能是由于草类可提取养分或不稳定碳含量的差异。BSFF 和 BWF 修正导致金属污染基质中微生物生物量显着增加。这可能是由于提供养分、能量和降低的金属生物利用度造成的：可提取的锌、铜、镉和镍的浓度由于金属吸附和络合增加而下降。所有 frass 类型都可以用作金属污染土壤的改良剂，而 BSFF 作为有机肥料显示出最有希望的，因为它的使用不会导致土壤亚硝酸盐的积累。