Dr. Eric Palevski, Newe Ya’ar Research Center.
Soils are the major reservoir of global biodiversity, the substrate for supporting agriculture and food security, regulating greenhouse gas emissions and water quality, and promoting plant, animal and human health. Without healthy living soils, critical ecosystem limits will be suddenly reached and the estimated safe human operating spaces rapidly decreased (Wall et al., 2015). Intensive farming has and continues to negatively impact soil organic carbon content and fertility, while increasing soil compaction and salinity, resulting in ever-increasing expenditures on inputs to substitute for eroded soils.
The production of quality soil amendments from wastes has become an important objective for the sustainable and efficient management of wastes and the conservation of soils. This interest stems both from the need to dispose of wastes in an environmentally safe and economically sound way and from the recognition that compost supplements are vital for the maintenance of soil fertility and increase crop production (Sayara et al., 2020). Furthermore, compost and other soil amendments including biochar and insect remains (also known as frass) can suppress pests such as root knot nematodes in soil either directly (Ferji et al., 2006; Mayad, 2011; Oka, 2010) or indirectly by boosting the plant defense mechanisms against pathogens via modulation of plant physiology and/or by stimulation of beneficial microbiota and mesofauna (Abd-Elgawad, 2021; Gebremikael et al., 2016; Harkes et al., 2020; Huang et al., 2015; Udalova et al., 2021). In addition, incorporating organic matter into the soil favors fertility, stores carbon, limits erosion, controls pathogens, favors a better water retention and enhances crop production (Haouas et al., 2021).
While the classic “open windrow” composting usually involves a long maturation period of several months, rotary drums may provide an alternative configuration for high-rate stabilization or “fast composting” (Oazana et al., 2020). By reducing the overall residence time, rotary drum composters may maximize the technology benefits to be implemented as an on-farm nutrients recovery approach. Conventional composting systems usually suffer from nitrogen losses, which downgrade the nutrient value of the raw biomass. By incorporating adsorbing agents like biochar (the charcoal solid product of woody biomass pyrolysis) both ammonia and odor emissions can be reduced (Agyarko-Mintah et al., 2017). Minimizing ammonia emissions from composting systems may improve the environmental signature of the process while reducing its carbon footprint. By conserving the nitrogen content in the composted product, the biomass residue (livestock manure, green waste, etc.) can be valorized into a valuable N-rich soil amendment to be returned to the soil.
With the increased production of insects for food and feed, insect frass is becoming available as a soil amendment, especially for the organic sector. The frass of Hermetia illucens, black soldier fly, was found to be as effective as commercial fertilizers (Klammsteiner et al., 2020), to enhance populations of bacteria and fungi and increase availability of nitrogen, phosphorus and magnesium (Beesigamukama et al., 2021). In Israel, black soldier fly frass (BSFF) was found to enhance root and foliage growth of tomato seedlings in potted plants, as well as the abundance of beneficial free living nematodes (FLN) and predatory mites (unpublished preliminary data). Recently, Azevedo et al. (2020) showed that the provisioning of FLN enhanced the abundance of predatory mites and the biological control of RKN.
In the picture (taken by Dr. Eric Palevski): A predatory mite about to feed on the larva of a plant parasitic nematode – an bioindicator for soil health
(1st prize FAO Soil biodiversity contest 2021)
Abd-Elgawad, M.M.M., 2021. Optimizing safe approaches to manage plant-parasitic nematodes. Plants 10, 1-2
Azevedo, L.H., Moreira, M.F.P., Pereira, G.G., Borges, V., de Moraes, G.J., Inomoto, M.M., Vicente, M., de Siqueira Pinto, M., Peres, L.P., Rueda-Ramírez, D., Carta, L., Meyer, S.L.F., Mowery, J., Bauchan, G.R., Ochoa, R., Palevsky, E., 2020. Combined releases of predatory mites and provisioning of free-living nematodes for the biological control of root-knot nematodes on ‘Micro Tom tomato’. Biol Control 146.
Beesigamukama, D., Mochoge, B., Korir, N., Ghemoh, C.J., Subramanian, S., Tanga, C.M., 2021. In situ nitrogen mineralization and nutrient release by soil amended with black soldier fly frass fertilizer. Sci Rep 11, 14799.
Ferji, Z., Mayad, E., Laghdaf, T., Cherif, E., 2006. Effect of organic amendments of Ricinus communis and Azadirachta indica on root-knot nematodes Meloidogyne javanica infecting tomatoes in Morocco. IOBC WPRS BULLETIN 29(4), 325.
Gebremikael, M.T., Steel, H., Buchan, D., Bert, W., De Neve, S., 2016. Nematodes enhance plant growth and nutrient uptake under C and N-rich conditions. Sci Rep 6, 32862.
Haouas, A., El Modafar, C., Douira, A., Ibnsouda-Koraichi, S., Filali-Maltouf, A., Moukhli, A., Amir, S., 2021. Evaluation of the nutrients cycle, humification process, and agronomic efficiency of organic wastes composting enriched with phosphate sludge. Journal of Cleaner Production 302, 127051.
Harkes, P., van Steenbrugge, J.J.M., van den Elsen, S.J.J., Suleiman, A.K.A., de Haan, J.J., Holterman, M.H.M., Helder, J., 2020. Shifts in the Active Rhizobiome Paralleling Low Meloidogyne chitwoodi Densities in Fields Under Prolonged Organic Soil Management. Frontiers in Plant Science 10.
Huang, W.-k., Ji, H.-l., Gheysen, G., Debode, J., Kyndt, T., 2015. Biochar-amended potting medium reduces the susceptibility of rice to root-knot nematode infections. BMC Plant Biology 15, 267.
Klammsteiner, T., Turan, V., Fernández-Delgado Juárez, M., Oberegger, S., Insam, H., 2020. Suitability of of black soldier fly frass as soil amendment and implication for organic waste hygienization. Agronomy 10, 1578.
Mayad, E., 2011. Sensibility of phytoparasitic nematodes (Meloidogyne javanica) associated to vegetable crops: Effect of southern Moroccan plants. Ibn Zohr, Morocco.
Oazana, S., Varma, V.S., Saadi, I., Sharma, D., Hanan, A., Medina, S., Avidov, R., Grinshpon, Y., Rosenfeld, L., Gross, A., Laor, Y., 2020. High-rate stabilization and associated air emissions prospected during on-site in-vessel sewage sludge composting. Bioresource Technology Reports 11, 100543.
Oka, Y., 2010. Mechanisms of nematode suppression by organic soil amendments—A review. Appl Soil Ecol 44, 101-115.
Sayara, T., Basheer-Salimia, R., Hawamde, F., Sánchez, A., 2020. Recycling of Organic Wastes through Composting: Process Performance and Compost Application in Agriculture. Agronomy 10, 1838.
Udalova, Z., Ushakova, N., Butorina, N., Zinovieva, S., 2021. Influence of insectocomposts through Hermetia illucens larvae on nematodes of various ecological-trophic groups. Research on Crops 22, 150-157.
Wall, D.H., Nielsen, U.N., Six, J., 2015. Soil biodiversity and human health. Nature 528, 69.